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  1. #66
    Tim Voss's Avatar
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    Default Re: Too much for 200A

    All I'm saying is that if I can light 400 1amp lights, I have the equivalent of 400amps of 120v power.

    If you read this link provided by Bruce, Single-phase power systems : POLYPHASE AC CIRCUITS it explains quite nicely how putting 2 120v loads in series on a 240v circuit works.

    I know, I know, I know I only have 200amps on the 240v main breaker wire, but if I meter the current going out to each lamp, it is 1amp. 1amp times 400 = 400amps of equivalent power at 120v. You agree I'm lighting 400amps of 120v lights? I don't see how you can say I don't have the equivalent of 400amp of 120v power? 240x200 = 120x400

    The main point I was trying to make when I said you have the equivalent of 400amps of 120v power, is that when you do a load calculation for all 120v loads on a residential 240v 200amp service, you add the amps up to 400, not 200 to make sure you are within load limits (of course there is 80% load factor to consider as well). Like the RV service mentioned above, for all 120v loads on a 240v service, you can calculate double the amps of loads you would calculate for 240v loads.

    If this is still not clear, then what about the fact that I can put an AC-AC voltage converter on my 240v 200a panel and pump out 120v at 400a (minus negligable conversion losses) without blowing the main breaker? Obviously the equivalent of 400amps at 120v is there.


  2. #67
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    Default Re: Too much for 200A

    Tim,

    Give it up, Jerry does not deal in "equivalent" or any discussion that is not black and white. He looks for the smallest error or misphrased post so he can correct you, its his hobby, and he is pretty darn good at it.

    I do appreciate his input on here though as I do everyones, its just sad that 98 percent of inspectors do not participate on message boards.


  3. #68
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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    All I'm saying is that if I can light 400 1amp lights, I have the equivalent of 400amps of 120v power.
    That's not all you've been saying.

    You've been saying you could do that through a 200 amp main.

    You can do what you just said through a 400 amp main, yes, but not through a 200 amp main. All you do is connect each lamp phase leg to neutral - no problem.

    The problem comes in when you try to do that through a 200 amp main, and, then, *again* ... no, you are incorrect - you do not have 400 amps ... "equivalent" or not, notwithstanding.

    If you connect them as has been described, you will only have 200 amps "equivalent" or "real".

    Now, if you were to do as James did and talk in power only (watts, kw, etc.), then you are ignoring 'voltage and amps' and talking only about 'power', in which case you would have the same 'power' usage ... just not the same "amps", which is what you keep bringing up.

    Regardless how many times you try to come up with 400 amps on that circuit with a 200 amp main, the answer will always be the same - "No, that is incorrect."

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  4. #69
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    Default Re: Too much for 200A

    Quote Originally Posted by Bruce King View Post
    Give it up, Jerry does not deal in "equivalent" or any discussion that is not black and white. He looks for the smallest error or misphrased post so he can correct you, its his hobby, and he is pretty darn good at it.
    Bruce,

    Incorrect assumptions again (you do seem to make a lot of incorrect assumptions about why other people do things, is that because that is why you do them?

    I don't look "the smallest error or misphrased post so he can correct you", if you make an incorrect post, it is likely because you are misunderstanding what is being discussed, doing so here present little threat of you being 'taken to the cleaners' by your clients or 'the trades' ... doing so 'out there' can lead to you being 'wrong' and not being able to back up what you said, or you having to say 'what I meant to say was ... ', which does not make you look good either.

    Better to learn here (or wherever) what is correct and what is not, than to learn in front of your client.

    It is however, ultimately your choice.

    Bruce,

    You were kind enough to, as I stated, "Bruce, thanks for splashing that bucket of ice cold water in my face and waking me up ... ", now, though, refill the bucket, add more ice, then splash over your face, then splash the rest on Tim's face, maybe it will help the two of you like it did me?

    Let me know if that wakes you two up like it did me, thanks.

    Jerry Peck, Construction / Litigation Consultant
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  5. #70
    Brandon Chew's Avatar
    Brandon Chew Guest

    Default Re: Too much for 200A

    Quote Originally Posted by Jerry Peck View Post
    Actually, what you have is *one* waveform, simultaneously in Phase A and Phase B.

    The current flow in Phase A and out Phase B for 1 120/sec, then flows in Phase B and out Phase A for the next 1 120/sec, then it repeats that process for the next 2 120/sec. At this point in time, 1/60 of a sec later, you have completed one cycle, one waveform which rises from 0 to +170 then drops to 0 to -170 then rises back to 0.

    Think of the water hoses being switched 60 times a second, what you are describing would be both water hoses being used on at the same time, creating no potential difference and thus no flow (voltage is potential, which is what creates current flow).
    I don't think that is correct and here is why.

    [Note to reader: comments about transformer in the next paragraph were revised and additional discussion of "phase" as applied to voltage, current, and power in this system was added by me in post #86.]

    To keep it simple and not go into three phase power, a typical transformer supplying a residential 3-wire single-phase 120/240V system has three windings inside it. On the primary side is one winding on a conductor from the power company's distribution system. On the secondary side are two windings, each one wrapped in opposite directions, that create two 120V wave forms (A & B) that are 180 degrees out of phase with respect to each other.

    A major reason for generating the A & B wave forms 180 degrees out of phase of each other is so that you are able to create a 240V potential between the two legs and have a dual voltage system. Having done that, a big side-benefit is that you are able to have current flowing out on the A and coming back on the B at the same time that current is flowing out on the B and coming back on the A. This is what results in the neutral having zero current flow when the loads on the A & B are perfectly balanced. The maximum unbalanced condition would result in a maximum current of 200A @ 120V flowing on the neutral back to the transformer, which allows us to size the neutral conductor to carry 200A @ 120V. If the A & B waveforms were generated in phase with each other, the neutral would have to be sized to carry 400A @ 120V back to the transformer.

    Refer to the diagram attached below. Maximum potential of each wave form with reference to zero (neutral) oscillates between +/- 170V (120V is an average value) as Jerry noted. The waves are 180 degrees out of phase to each other. This creates a maximum potential difference of +/- 340V (240V average) when you measure between the peak of one wave to the other. Both waves begin at the same time and they cross the zero line every 1/120 second.

    [note to reader: there is incorrect info in the next two paragraphs about current flow. I have retracted these two paragraphs and have posted a correct description of current flow in post #86]

    Jerry, the analogy between water flowing and electricity flowing is a good one for most things. It breaks down when you transition from discussing DC current to AC current. Thinking in terms of water makes it difficult for people to grasp the concept that electrons can be flowing along a conductor in two directions at the same time. It's the two windings in the transformer generating two 120V currents out-of-phase by 180 degrees that is the key to making this physically possible.

    The water analogy (two hoses drawing water from the transformer at the same time) does work to illustrate what happens once the loads on the A & B become unbalanced (which is the common real-world situation in residential panels), or if the A & B are being generated in phase with each other. With A & B 180 degrees out-of-phase with each other, at any given point in time that current is being drawn through the A leg to the house, the capacity of the A leg to return the current that is being drawn from the B leg back to the transformer is limited to an amount that is relative to the current being drawn by the A leg. The excess draw from the B leg has to go back on the neutral. If the A & B are being generated in phase with each other, neither the A or B could carry any flow back to the transformer, and all of the flow from both of them would go back on the neutral at the same time. When A & B "hoses" were both flowing at their maximum rate of flow in phase with each other, the neutral "hose" would need to be twice the size of either one of them.

    If there are some 120V loads attached to the A leg and other 120V loads attached to the B leg, or if you have 240V loads attached to both legs, then current is flowing from the transformer through both the A & B at the same time. Current flow does switch directions every 1/120 second, but it's switching directions in the A & B at the same time.

    On three-wire single-phase 120/240V residential service that is sized for 200A:
    • the conductor on the A leg is sized to carry up to 200A @ 120V
    • the conductor on the B leg is sized to carry up to 200A @ 120V
    • the neutral conductor is sized to carry up to 200A
    • the main OCPD is sized for up to 200A @ 240V
    The OCPD monitors the current flowing (amps) on each leg and will trip, killing the power to both legs, if either the A or the B pulls more than 200A @ 120V.

    Through a "200A" residential service, you have the ability to pull up to 400 amps of power at 120 volts off the transformer if the 120V and 240V loads on A & B are perfectly balanced, but you cannot pull more than 200 amps (at 120V) through either the A or the B.

    [Final note to reader - See post #90. It is best to describe the power being pulled from the transformer at maximum load as "48,000 watts by a 120/240V 3-wire 1-phase system", and the household system is sized and rated for "200 amps". Although you can pull 200A @ 120V through the A & B legs at the same time, you should not measure more than 200A anywhere in the system. From post #86, the current waveforms on the A & B legs are mirror images of each other. When currents of opposite signs (+/-) are added together they cancel each other out, which is why, on a balanced system the grounded conductor carries zero amps. The current you measure on the grounded conductor is showing you the practical result of adding the two 200A current flows on the A & B together.]

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    Last edited by Brandon Chew; 04-04-2008 at 08:44 AM. Reason: Add notes to reader based on later posts.

  6. #71
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    Default Re: Too much for 200A

    Brandon,

    This is the way most single phase power transformers are wound ( Single Phase Transformers - Power Transformer Co - see drawings and text).

    The current is flowing through the secondary winding in one direction for half of the cycle, then reverses for the other half of the cycle. This creates one current path, in one direction, and one waveform for that current.

    Taping off the center give 240 volts to both phase legs or 120 volts between either phase leg and the grounded center point.

    When installing the loads as has been discussed, there is no grounded center point current flow (no neutral current), thus, all of the current is going in the same direction at the same time, thus one waveform for the current.

    If you were to introduce two opposing waveforms, there would be no current flow. You need the electro-motive force provided by the difference in potential, and two opposing waveforms would cancel each other out, creating no potential difference which is needed to drive the current flow.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  7. #72
    Michael P. O'Handley's Avatar
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    Default Re: Too much for 200A

    Aargh!

    Reading and trying to follow this is making my head begin to throb the way it did in high school algebra (For anyone that doesn't know it, I'm a math moron.).

    Is there anyone in the business that you both (Peck and Chew) would recognize as being THE authority on this subject and who's opinion on this point you both would accept without challenging or endless debate?

    This is important stuff and the danger is that anyone reading this thread can decide who they want to believe is correct and will then follow that persons guidance even if that person is 100% wrong. Well, this isn't stuff that you can have a different opinion about; this is real honest-to-goodness quantifiable stuff that's subject to scientific absolutes, so one of you has to be wrong. That means anyone accepting the wrong person's interpretation could potentially get themselves, or their clients, killed. That especially goes for me, 'cuz despite 12 years in this business I'm still not "comfortable" around this subject. I don't like 50% odds of being wrong and screwing this up. I like odds that are well in favor of me being right, so I won't get myself 'lectricuted.

    I think we need someone else to step in here who's THE guru. Once that person renders an opinion, I think both of you, for the sake of all of us out here who are still largely mystified by electricity, should accept that opinion and let it end there and not dispute anyone in the future that ventures the same opinion.

    Someone has to be wrong here and someone has to be right, so I'm challenging you both to end this by choosing an impartial 3rd party to say who right. Who's it going to be? Mike Holt? Hansen? Katen? Simmons? Cramer? Cory Friedman? Joe Tedesco? Rex Cauldwell? Who? Comeon, comeon, name your poison, I'll copy the whole damned thread, shoot it to the one person who's opinion you both can accept and get it from the mountaintop so that we can get the definitive answer to this and end the confusion.

    Comeon guys, step up.

    ONE TEAM - ONE FIGHT!!!

    Mike


  8. #73
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    Default Re: Too much for 200A

    Quote Originally Posted by Michael P. O'Handley View Post
    Is there anyone in the business that you both (Peck and Chew) would recognize as being THE authority on this subject and who's opinion on this point you both would accept without challenging or endless debate?
    Mike,

    This isn't "endless", the end is almost in sight.


    Mike Holt
    There's your answer from this end. [ (added with edit) I agree with most of what Mike says, but there are a few things I disagree with him on. ]

    But remember, we are almost at the end right now, so hold off until next week (only two more days this week anyway), if we are not in agreement by then, go for it.

    Last edited by Jerry Peck; 04-02-2008 at 05:42 PM. Reason: see (added with edit) comment
    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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  9. #74
    Brandon Chew's Avatar
    Brandon Chew Guest

    Default Re: Too much for 200A

    Hi Mike,

    From my point of view I don't see my two posts in a thread 72 posts long as me being locked in an endless debate. I've laid out what my current understanding of the subject is for all to view. I haven't tried to claim I was an expert or insist I'm right. In fact, I'll state flat out that my degree is not in electrical engineering -- but that doesn't mean I don't know anything about the subject.

    I do want to get it right. So in those two posts I've climbed out on a very long limb knowing there's plenty of guys eager to start sawing on it. I've got my parachute on and when I hit the ground I hope to dust myself off, look back on where I was, and learn something that I didn't know before I started.

    I couldn't name one person who's word I'd accept as gospel without first listening to what they said on the subject and how they said it. That's just the way I am, and why I enjoy the process of learning as much as I do. So, to answer your question, I'd be thrilled if you got all of those guys to weigh in!

    I just hope some folks can refrain from the name-calling and personal attacks and we get some new info into the thread instead of recycling the same stuff over and over again.

    Brandon


  10. #75
    Brandon Chew's Avatar
    Brandon Chew Guest

    Default Re: Too much for 200A

    Quote Originally Posted by Jerry Peck View Post
    Brandon,

    This is the way most single phase power transformers are wound ( Single Phase Transformers - Power Transformer Co - see drawings and text).

    The current is flowing through the secondary winding in one direction for half of the cycle, then reverses for the other half of the cycle. This creates one current path, in one direction, and one waveform for that current.

    Taping off the center give 240 volts to both phase legs or 120 volts between either phase leg and the grounded center point.

    When installing the loads as has been discussed, there is no grounded center point current flow (no neutral current), thus, all of the current is going in the same direction at the same time, thus one waveform for the current.

    If you were to introduce two opposing waveforms, there would be no current flow. You need the electro-motive force provided by the difference in potential, and two opposing waveforms would cancel each other out, creating no potential difference which is needed to drive the current flow.
    Jerry - Thanks. I need some time to think about this and digest the info. Right now my belly says it's time for dinner!


  11. #76
    Michael P. O'Handley's Avatar
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    Default Re: Too much for 200A

    Hi Brandon,

    I know your's was only two posts but I know you're an engineer and I know Jerry is, well, Jerry. In this thread, you two seem to be the.....experts, shall we say.

    Nuff said. There's still a need for a definitive answer 'cuz there are others in your corner on this thing. Electrical stuff is important. If we're going to state it on a forum, and it's about the science and not just about how to interpret a rule, folks need to get it right.

    ONE TEAM - ONE FIGHT!!!

    Mike


  12. #77
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    Default Re: Too much for 200A

    Here's the real deal, no need for an "expert" but it would be nice to hear from an AC power expert, not a code guy. Keep in mind that engineers are not always right either. I could write a book on that.



    Jerry is technically right about the 200 amps being max due to the AC waveform, transformer, neutral, current waveform, series circuit etc. I remember most of this from school but can't explain it very well because that was 30 years ago.

    But:

    I thought the discussion was primarily about "can you drive four 100 amp loads at 120V?" and the answer is YES, we all agree on that.


    Then we started talking about equivalent etc. for the sake of explaining things to those who do not know all of the AC theory in detail. Then Jerry jumped in, which is ok because some of us were trying to simplify it and say the main was passing 400 amps total.


    I posted that the main sensed heat/watts as the current monitoring method, this is correct for many smaller breakers but those big ones use a magnetic trip mechanism that is activated by current, so Jerry was right on that.


    These things argued previously are actually very correct:
    (Jerry will still argue something but will be wrong on these)

    120V x 400 amps = 48,000 watts
    240V x 200 amps = 48,000 watts

    Amps and watts can be easily converted using simple math when the voltage is known. We should have used watts and made this much easier possibly.

    50 amp RV's ARE fed with 240/120V up to the interior control panel just like a range circuit although the rigs distribution is wired as two 120V 50 amp busses. You can get 50 amps off each bus (2) in the RV at 120V.


  13. #78
    Carl Eisen's Avatar
    Carl Eisen Guest

    Default Re: Too much for 200A

    Quote Originally Posted by Jerry Peck View Post
    Actually, what you have is *one* waveform, simultaneously in Phase A and Phase B.

    The current flow in Phase A and out Phase B for 1 120/sec, then flows in Phase B and out Phase A for the next 1 120/sec, then it repeats that process for the next 2 120/sec. At this point in time, 1/60 of a sec later, you have completed one cycle, one waveform which rises from 0 to +170 then drops to 0 to -170 then rises back to 0.

    Think of the water hoses being switched 60 times a second, what you are describing would be both water hoses being used on at the same time, creating no potential difference and thus no flow (voltage is potential, which is what creates current flow).

    I think I have my head just about straight on this. My error is looking at it as two opposing wave forms. Which at having the same amplitude would cancel each other out and thus no flow of current and no horsepower on the business end.


  14. #79
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    Default Re: Too much for 200A

    Quote Originally Posted by Bruce King View Post
    These things argued previously are actually very correct:
    (Jerry will still argue something but will be wrong on these)

    120V x 400 amps = 48,000 watts
    240V x 200 amps = 48,000 watts

    Amps and watts can be easily converted using simple math when the voltage is known. We should have used watts and made this much easier possibly.

    50 amp RV's ARE fed with 240/120V up to the interior control panel just like a range circuit although the rigs distribution is wired as two 120V 50 amp busses. You can get 50 amps off each bus (2) in the RV at 120V.
    Bruce,

    I only argue a point when there is something which needs to be 'argued', i.e., corrected, debated, discussed, resolved to the right answer.

    There is nothing to correct in your post above. Nothing which needs to be argued.

    It's just that's not what was stated above in the other posts.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  15. #80
    Tim Voss's Avatar
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    Default Re: Too much for 200A

    ONLY IF there are 200 between Phase A and Neutral and 200 Between Phase B and Neutral.

    I thought you just said I COULD put 400 1amp 120v lights on a 200amp main. 200 on Phase A and 200 on Phase B. Now you are saying I CAN'T do it?

    I'm not quite ready to give up, so let's just start with something we both agree on. On a 200amp 240v service, can I light 400 1amp 120v lights (your basic 120watt regular light bulb)? 200 on each Phase, yes or no?


  16. #81
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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    I thought you just said I COULD put 400 1amp 120v lights on a 200amp main. 200 on Phase A and 200 on Phase B. Now you are saying I CAN'T do it?
    No, what I'm saying, and have been saying, is that you CAN ... BUT ONLY IT you balance them between Phase A and Neutral and between Phase B and Neutral.

    Previously you said you could "put 400 1amp 120v lights" ... but did not add the "on a 200amp main" condition. Without that condition you can, but, as I said "You can do what you just said through a 400 amp main, yes, but not through a 200 amp main. All you do is connect each lamp phase leg to neutral - no problem."

    AS SOON AS you add that condition (the 200 amp main), the answer changes, and the only way is to balance them out between the neutral and the phases.

    I'm not quite ready to give up,
    Good, I don't want you to give up, I am hoping you will understand it.

    *MIKE* wants you to give up, or someone to give up. Mike does not like disorder, Mike likes to control things, which he offered to do above. Learning involves a lot of disorder in order to be able to work one's way through the thought process.

    so let's just start with something we both agree on. On a 200amp 240v service, can I light 400 1amp 120v lights (your basic 120watt regular light bulb)? 200 on each Phase, yes or no?
    Yes. As long as each lamp is between a phase leg and neutral, balancing them between Phase A and Phase B.

    Yes.

    Jerry Peck, Construction / Litigation Consultant
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  17. #82
    Tim Voss's Avatar
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    Default Re: Too much for 200A

    Ok, I agree. I can have 400 lights as long as they are perfectly balanced with 200 on phase A to neutral and 200 on phase B to neutral.

    So now I'm trying to determine if I have too much load for a 240v service. Let's say I only have 120v loads - lights, appliances, refrigerator, etc... ALL 120v. Assuming all these 120v loads are perfectly balanced out between the two phases and neutral, can I add up the amps for all my 120v loads up to double the main breaker rating and still not be overloaded?


  18. #83
    Bob White's Avatar
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    Talking Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    Ok, I agree. I can have 400 lights as long as they are perfectly balanced with 200 on phase A to neutral and 200 on phase B to neutral.

    So now I'm trying to determine if I have too much load for a 240v service. Let's say I only have 120v loads - lights, appliances, refrigerator, etc... ALL 120v. Assuming all these 120v loads are perfectly balanced out between the two phases and neutral, can I add up the amps for all my 120v loads up to double the main breaker rating and still not be overloaded?

    Yeah ---

    When can we start adding motor loads and switching electronic loads to the mix???

    I'm tired of just using linear loads....


  19. #84
    Michael P. O'Handley's Avatar
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    Default Re: Too much for 200A

    Quote Originally Posted by Jerry Peck View Post
    *MIKE* wants you to give up, or someone to give up. Mike does not like disorder, Mike likes to control things, which he offered to do above. Learning involves a lot of disorder in order to be able to work one's way through the thought process. Yes.
    That's pretty funny. Anyone who really knows me would never say that because they realize I live in a constant state of disorder.

    No, what I want, and I'm sure others reading this thread want, is to know which side of the argument is accurate. You wear people down Jerry, and if you do it to someone while arguing about electricity, how is anyone reading the thread to know that you've won the argument because you were right or because folks simply got tired and walked away?

    It seems to me, that the folks arguing with you here are smart fellows, and that if your arguments were so strong, and accurate, that they wouldn't have stood their ground and continued to argue their points and would have quietly accepted it long ago. So, at the end, when you've completely worn them down, who do the rest of us believe? If we believe your explanation, and you are wrong, what value has all this produced? From where I'm standing, the question has never been answered in such a way that I'd feel comfortable with either side's argument.

    It's like a group of students arguing about the solution to a problem where everyone is convinced he knows the right answer but anyone listening to them argue only becomes more unsure. At some point, if they're as smart as they want folks to think they are, they produce documented proof of their positions, or they consult their professor, who is the authority, to settle the argument. In the end, someone obviously has to be wrong but without a professor here to tell the rest of us that he agrees with one side or the other, how can the rest of us, who are not electricians - and the last time I looked you weren't either - have confidence in either side's argument.

    At this point, all that's been proven to me is that folks have grown tired arguing and are quitting the discussion. I still don't know who's right and, because electricity is so dangerous, I'd like to know. That's why I suggested taking it to an independent third party.

    We need a professor here; that's all I'm saying.

    ONE TEAM - ONE FIGHT!!!

    Mike


  20. #85
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    Default Re: Too much for 200A

    We are at the point of just needing another good source of info (in laymans terms) on how the AC voltage and current behaves directionally within the circuit. You have to remember this though, most electrical/electronic instructors start off by asking the class which method the class prefers to use, conventional current flow or electron current flow. This difference alone causes more arguments between engineers and technicians. Automotive guys like conventional current flow, engineer types like electron flow.


    The amount of current issue has been settled, its 200A max but you can have balanced series operation with 120V loads that add up to a 48kw load.
    Four one-hundred amp loads at 120V equals 48kw.


    How many guy's have heard the term ELI the ICE man that is used to help remember the following?

    The L is an inductive circuit, the C is a capacitive circuit.
    E is voltage and I is current.
    Voltage leads current by 90 degress in an inductive circuit.
    Current leads voltage by 90 degrees in a capacitive circuit.

    It only gets more complicated with different load types.

    The 60hz AC wave can be confusing to explain.


    Jerry is correct in his ongoing message on this board "getting the terminology right is important to understanding and communicating issues"


  21. #86
    Brandon Chew's Avatar
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    Default Re: Too much for 200A

    OK, I'll saw my own tree limb. Jerry made a nice start. There are two things I have wrong and one thing I should clarify in my post #70.

    First thing wrong and a clarification:
    To keep it simple and not go into three phase power, a typical transformer supplying a residential 3-wire single-phase 120/240V system has three windings inside it. On the primary side is one winding on a conductor from the power company's distribution system. On the secondary side are two windings, each one wrapped in opposite directions, that create two 120V wave forms (A & B) that are 180 degrees out of phase with respect to each other.
    The typical transformer for a residential 3-wire single-phase 120/240V system is not the one I described with three windings. That transformer is a special transformer that would be used to create two different power sources that you wanted to keep isolated. As Jerry pointed out, the typical transformer for residential systems has two windings, one primary (poco side) and one secondary (house side). The secondary winding has enough turns to create 240V. To get 120V, they tap the secondary winding in the center to create one dual voltage system.

    Now the clarification. While it's true that the center tapped secondary results in sine waveforms for voltage and current on the A & B legs that are 180 degrees out of phase with respect to each other when viewed from a common ground, describing that difference with the term "phase" can create confusion among folks in the electrical field, especially when you start talking about the differences between single-phase and three-phase power systems.

    To avoid that confusion, it might be better to describe the voltage and current sine waves as having mirror images of each other. If you measured voltage on the A leg and the B leg over time with respect to a common ground and plotted them, you would have a picture like the one attached below.

    The secondary coil in the transformer creates a 240V AC power source with a positive pole on one end and a negative pole on the other. When we tap the coil in the center we create two 120V AC power sources linked in series. When we ground that center tap at the transformer and attach 120V loads to A & B, we ensure that power always leaves the transformer at the ends of the coil and returns to the transformer through the grounded conductor at the center.

    When loads are pulling current through both A & B, and we have a good system that is keeping the voltage stable, measuring voltage between each leg and the common ground will always result in a plot like the one in the picture -- two sine waves with a common start, equal amplitudes, and that cross the zero line at the same time -- mirror images of each other. What's important to note about the voltage plot is that while each leg is 120V with respect to ground, one is +120V while the other is -120V, depending upon which end of the secondary coil is currently positive or negative. They switch every 1/120 second which is shown as a crossing of the zero line on the plot. With voltage we are concerned about potential difference. So when we measure the voltage across A & B we do not simply add +120 to -120 and get zero and say they cancel each other out, we add the absolute values, 120 + 120, and get 240 volts potential between them.

    Now let's look at current flow, or amps. Amps = load/volts. As a practical limitation, the value for load cannot be negative. Something creating a "negative load" would be a power source or a generator. As we saw when we looked at voltage, the voltage on the A & B oscillates between +/- 120 volts. A plot of the amps on A & B will yield two sine waves with a common start and that cross the zero line at the same time. At any given point in time (moving to the right on the x-axis), the amplitudes (distance from the wave to the zero line) of the A & B sine waves will be equal ("mirror images", like they are in the picture) only when equal loads are placed on the A & B -- a/k/a the loads are balanced. When the loads are unbalanced, the amplitude of one sine wave will be greater than the other but the crossover points will be unchanged.

    When the current flows through the A & B to their loads and then back to the transformer on a common grounded conductor, the current flowing on that common conductor is arithmetically added together. In this case positive and negative currents subtract from each other, while currents of the same sign (+/+ and -/-) add together. When the loads on A & B are balanced, the magnitudes of the current are the same and the signs are opposite -- the sum is zero and no current is flowing on the grounded conductor. When the loads are unbalanced, magnitudes of the current are now different but the signs are still opposite -- the excess current flows on the grounded conductor at the potential difference between the A & B legs, 240V.

    Now the power curve for the system that is derived by taking measurements on the A & B legs with a common ground reference, does not look like the graph in the picture. It would look similar to what would happen if you took that picture and you erased the portions of the waves below the zero line and just had the part above it. The reason is that power = watts = volt amperes = volts X amps. In this system, volts and amps can be either positive or negative, but they are always the same sign at any given point in the system -- when volts are negative, amps are negative, and vice versa. When you multiply two negative numbers together you get a positive number. Power draw is always additive, which makes sense -- more load draws more power.

    For the wave forms on the A & B legs, and when measured using a common ground reference, we can say: the voltage waves are 180 degrees out of phase with each other, the current waves are 180 degrees out of phase with each other, but the power waves are additive and are in phase with each other -- as they should be in a single-phase power system.

    Now for my second error, and this one was really a "left turn at Albuquerque!" I don't know what the hell I was thinking when I wrote that. If I had thought about it more before I hit the post button I would have caught it. I'm going to blame it on a combination of fatigue due to typing with one hand, pain in my left hand, and pain meds.

    Jerry, the analogy between water flowing and electricity flowing is a good one for most things. It breaks down when you transition from discussing DC current to AC current. Thinking in terms of water makes it difficult for people to grasp the concept that electrons can be flowing along a conductor in two directions at the same time. It's the two windings in the transformer generating two 120V currents out-of-phase by 180 degrees that is the key to making this physically possible.

    The water analogy (two hoses drawing water from the transformer at the same time) does work to illustrate what happens once the loads on the A & B become unbalanced (which is the common real-world situation in residential panels), or if the A & B are being generated in phase with each other. With A & B 180 degrees out-of-phase with each other, at any given point in time that current is being drawn through the A leg to the house, the capacity of the A leg to return the current that is being drawn from the B leg back to the transformer is limited to an amount that is relative to the current being drawn by the A leg. The excess draw from the B leg has to go back on the neutral. If the A & B are being generated in phase with each other, neither the A or B could carry any flow back to the transformer, and all of the flow from both of them would go back on the neutral at the same time. When A & B "hoses" were both flowing at their maximum rate of flow in phase with each other, the neutral "hose" would need to be twice the size of either one of them.
    The current cannot flow on the same conductor in two directions at the same time -- that's gibberish! On the 120V circuits the current flows from the A and B poles on the secondary coil through the main OCPD, then to their respective loads, then back on the grounded conductor. On the 240V circuits the current flows from either the A or the B, whichever pole is positive at the time, through the main OCPD, to the load, and then back to transformer on either the A or the B, whichever pole is negative at the time. On the 120V and 240V circuits the A & B poles are changing polarity every 1/120 seconds.

    The reason I said I wasn't going to choose sides when I stepped into this discussion was because I think both sides are right when they speak the same language. You could describe a 200A household system as pulling off the transformer either 200A @ 240V or 400A @ 120V through two 200A legs. The transformer doesn't care how you want to say it as long as you specify the volts along with the amps (a/k/a the power, or watts, or volt amperes are the same either way). My personal preference is 200A @ 240V because in the residential system the ampacity of the service conductors and the rating of the main OCPD are all 200A, and that 400A situation will occur only when the loads on A & B are balanced, which would be unusual to find in a residential system.

    Last edited by Brandon Chew; 04-03-2008 at 09:22 AM. Reason: add missing word and change last sentence

  22. #87
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    Default Re: Too much for 200A

    Here's the diagram again.

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  23. #88
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    Default Re: Too much for 200A

    Nice explanation there.

    Jerry must be taking the day off.

    You are in big trouble for using "400A" in the post.......
    Wait till Jerry gets back......

    Four 100a loads is the best way to describe that 400a issue.


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    Default Re: Too much for 200A

    Quote Originally Posted by Brandon Chew View Post
    You could describe a 200A household system as pulling off the transformer either 200A @ 240V or 400A @ 120V through two 200A legs.
    The correct way to address that would be to state that you are drawing 48,000 va at either 120 volts or at 240 volts.

    To throw in "400A @ 120V" is a misnomer as there is not "400A" anywhere in that circuit. (Note: I edited this line to change "To through in" to "To throw in".)

    The transformer doesn't care how you want to say it as long as you specify the volts along with the amps (a/k/a the power, or watts, or volt amperes are the same either way).
    The transformer does not care, because it is not even thinking in volts/amps/va. However, as soon as humans try to describe the limitations of a circuit with a 200 amp main, the limitation is ... 200 amps, not more, and in no way, shape or form is there "400 amps" anywhere in there.

    The other correct way would be to state you have 200 amp at 240 volts with 24,000 va on each phase at 120 volts, or, to more simply state it: you have 200 amps at 240 volts with the loads balanced across the phases and the neutral ... (technically, with those lamps, you would not even need to connect to the neutral as their resistance, and resulting current flow, are so close to each other that there would be such little difference at each lamp without a neutral grounding point that the neutral grounding point is not required - with motors, though, the neutral grounding point would absolutely be necessary to maintain the balance across the phase conducts and the neutral conductor and avoid burning motors up).

    Last edited by Jerry Peck; 04-03-2008 at 08:07 PM. Reason: for reader's ease of reading "to through in" should be "to throw in" - see quoted section below in Brandon's post
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  25. #90
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    Default Re: Too much for 200A

    Quote Originally Posted by Jerry Peck View Post
    The correct way to address that would be to state that you are drawing 48,000 va at either 120 volts or at 240 volts.

    To through in "400A @ 120V" is a misnomer as there is not "400A" anywhere in that circuit.

    The transformer does not care, because it is not even thinking in volts/amps/va. However, as soon as humans try to describe the limitations of a circuit with a 200 amp main, the limitation is ... 200 amps, not more, and in no way, shape or form is there "400 amps" anywhere in there.

    The other correct way would be to state you have 200 amp at 240 volts with 24,000 va on each phase at 120 volts, or, to more simply state it: you have 200 amps at 240 volts with the loads balanced across the phases and the neutral ... (technically, with those lamps, you would not even need to connect to the neutral as their resistance, and resulting current flow, are so close to each other that there would be such little difference at each lamp without a neutral grounding point that the neutral grounding point is not required - with motors, though, the neutral grounding point would absolutely be necessary to maintain the balance across the phase conducts and the neutral conductor and avoid burning motors up).
    Ok, I'll buy that. As mentioned I would't attempt to describe it as 400A anyway.

    For folks who followed the discussion of sine waves in my last post, nowhere in the system will you measure 400 amps -- the most you will measure is 200 amps. If the system is working right and you are pulling the max 48 kW off the transformer, the most you will see on the A or the B legs is 200 amps. When A & B come together on the common grounded conductor and go back to the transformer, recall that the current waveforms are mirror images of each other, so when you add those currents with opposite signs (+/-) together they want to cancel each other out. As a result the common grounded conductor would have a minimum of zero amps on it from 240V loads or when 120V loads are equally balanced on the A & B, up to a maximum of 200 amps flowing on it when the loads are unbalanced.




  26. #91
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    Default Re: Too much for 200A

    WHEW!


  27. #92
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    Default Re: Too much for 200A

    Just one question.

    Say I only have 120v loads on my 200a 240v service, and they just happen to be perfectly balanced between the phases. I look at the nameplate on my refrigerator and it says, 120v/60Hz 7.7amps and my vacuum says 120v/60Hz 9.2amps, etc...

    If I add up all the amps of my 120v devices I have plugged in and running, can I run 400amps of 120v devices at the same time without blowing the 200a 240v main breaker?


  28. #93
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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    Just one question.

    Say I only have 120v loads on my 200a 240v service, and they just happen to be perfectly balanced between the phases. I look at the nameplate on my refrigerator and it says, 120v/60Hz 7.7amps and my vacuum says 120v/60Hz 9.2amps, etc...

    If I add up all the amps of my 120v devices I have plugged in and running, can I run 400amps of 120v devices at the same time without blowing the 200a 240v main breaker?
    My oh my! I gave up reading this thread as it morphed into something that made my head spin...but they still haven't answered that basic question?

    I'll take one final stab at it (without mentioning 400-amps in any way because that seems to get peoples' knickers twisted).

    Tim, perhaps a simpler way of putting it would be to ask if you could fully load 20 20-amp 120 volt circuits (assuming they were 10 per leg). And the simple answer is yes.

    To make it even simpler, picture a panel with only one double-pole 20-amp breaker, the type with a handle tie. You can run a full 20-amp 240 volt load on that. Remove the handle tie and rewire to create two 120-volt circuits. Hopefully, no one is going to suggest that you couldn’t run 2 20-amp 120 volt devices at the same time. Putting the handle tie back on will not make it trip.

    The 200-amp main breaker is no more than a big 200-amp double pole breaker. That is two 200-amp breakers, usually with an internal common trip mechanism, but also sometimes with external handle ties. It works the same as the 20-amp example, just times 10.

    I'll let you do the math.


  29. #94
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    Default Re: Too much for 200A

    Thanks Richard, I did the math and it comes up to the controversial 400amps (at 120v). That's why I was really waiting to see what Jerry had to say.

    It's been an interesting discussion, but the home owner doesn't know or care about voltage waveforms and what goes on inside the "black box" of the service panel. They just want to know how much "stuff" can they plug-in.


  30. #95
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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    Just one question.

    Say I only have 120v loads on my 200a 240v service, and they just happen to be perfectly balanced between the phases. I look at the nameplate on my refrigerator and it says, 120v/60Hz 7.7amps and my vacuum says 120v/60Hz 9.2amps, etc...

    If I add up all the amps of my 120v devices I have plugged in and running, can I run 400amps of 120v devices at the same time without blowing the 200a 240v main breaker?
    Yes. Bruce mentioned something like this a few posts above this one for a situation with four 120V 100A loads when he wrote:

    "Four 100a loads is the best way to describe that 400a issue"

    The problem comes when you try to say this means the house service is rated for 400A @ 120V. You are drawing 48 kW of power off the transformer by a number of 120 V devices whose nameplates total 400 amps. Because the current (amps) is coming from opposite ends (+/-) of the transformer coil on two different legs to the house and returning on a common neutral, the house service is rated at 200A because that should be the most current you would measure on any of the service conductors.

    I entered this discussion thinking you could describe the house service in terms or either 200 or 400 A if you were careful enough about how you did it, but the reality is (and the theory backs it up) that there really isn't a practical reason to try to describe the service in terms of 400A, and wound up agreeing with the 200A side.

    Richard - nice description.


  31. #96
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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    It's been an interesting discussion, but the home owner doesn't know or care about voltage waveforms and what goes on inside the "black box" of the service panel. They just want to know how much "stuff" can they plug-in.
    Hi Tim,

    I wouldn't get into that discussion with a homeowner either. I needed to work through the theory here to get past the "I'm right!", "No, I'm right!" phase that this thread had seemed to be locked into, and to test and clarify my own understanding of the subject. It's been educational.

    Brandon

    (grits teeth and looks back over shoulder for Jerry's comments on my previous post)


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    Default Re: Too much for 200A

    Quote Originally Posted by Richard Moore View Post
    To make it even simpler, picture a panel with only one double-pole 20-amp breaker, the type with a handle tie. You can run a full 20-amp 240 volt load on that. Remove the handle tie and rewire to create two 120-volt circuits. Hopefully, no one is going to suggest that you couldn’t run 2 20-amp 120 volt devices at the same time. Putting the handle tie back on will not make it trip.

    The 200-amp main breaker is no more than a big 200-amp double pole breaker. That is two 200-amp breakers, usually with an internal common trip mechanism, but also sometimes with external handle ties. It works the same as the 20-amp example, just times 10.
    (sigh)

    Richard,

    You started out on the right track, keeping everything at 240 volts ...

    ...but, as soon as you split that double pole 20 amp breaker into 2 separate 20 amp breakers on 120 volt circuit, you changed the entire equation.

    How? You ask ...

    Here is how:

    *IF* (and ONLY *IF*) those two 20 amp breakers remained in the same location (i.e., one on Phase A bus and one on Phase B bus) - then nothing changes - you essentially have (still have) a 240 volt load made up of balances 120 volt loads, with no neutral current.

    NOW *HOWEVER*, if you separate those two 2 amp breakers leaving one empty space between them, you have removed them from being on different phase legs and they are now on the same phase leg, making their currents additive *at 120 volts* instead of benefiting from having had them at 240 volts.

    The difference between them and the 200 amp main is much more than "just times 10", the difference is that YOU CANNOT SEPARATE the 200 amp main into 120 volt legs ONLY - either BOTH will have the same current and the neutral will have no current (i.e., 200 amps maximum flowing through them), OR BOTH will have the same current as the lower one AND the neutral will have the current difference to the higher one (i.e., *less than* 200 amps flowing through them).

    Oh, and, don't forget, "*less than* 200 amps will still flow through a 200 amp main.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Too much for 200A

    Electricity 001 (it's not even Electricity 101 )

    You must have a complete circuit for current to flow.

    Take a 200 amp main, install a 240 volt breaker, install one conductor from one side of the breaker to a 200 amp 240 volt load, install another conductor from the other side of the breaker to a switch with the switch in the "open" position, then connect the yet another conductor from the other side of the switch to the other side of the 200 amp 240 volt load.

    How much current flows?

    NONE.

    The current MUST be able to get from one side of the main back to the other side of the main. Using one side does nothing.

    Throw the switch "closed". Now how much current flows?

    200 amps. No more.

    But ... but ... but there are *TWO* (count them Jerry) TWO 200 amp breakers there, THAT'S 400 AMPS - DO THE MATH JERRY.

    That's what some of you are saying. So I am saying, simply, *SHOW ME THE 400 AMPS*.

    I have reduce all the above posts down to this one simple, easy to understand post, with one easy to understand question.

    SHOW ME THE 400 AMPS

    Jerry Peck, Construction / Litigation Consultant
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  34. #99
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    Default Re: Too much for 200A

    400 light bulbs x 1 amp each = 400amps

    You keeps saying it's the same amp, but it is not exactly the same amp. If you put two 120v light bulbs in series to make a 240v circuit, yes only 1 amp flows through each bulb, but you have to count that amp each time it flows through a load. The first bulb only uses 120volts of the 240volt potiential, the second bulb uses the remaining 120volts of potential.

    1amp x 240volts = 2amps x 120volts = 240watts of power

    Right there in the math you can see that you have to count the amp each time it passes through the 120volt load. They all add.

    The light bulb is stamped 120v and 1amp right on the bulb! If I have 400 of them lit simultaneously, I have 400amps (at 120volts). The light bulb doesn't know what circuit it is in, it only knows that when 120volts is applied it uses 1amp. All 400 could be in series on a 48,000volt circuit with only 1 amp flowing. Doesn't matter, each bulb has a 120volt drop and uses 1 amp. Add them up = 400amps total at 120v or 1amp total at 48,000volts or 200amps total at 240volts.

    Since the bulb is 120v, you are running 400amps of 120volt loads. Bottom line is, I can add all the amp ratings of my 120v appliances and put 400amps of load on a 200amp 240v service.


  35. #100
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    Default Re: Too much for 200A

    Quote Originally Posted by Jerry Peck View Post
    (sigh)

    Richard,

    You started out on the right track, keeping everything at 240 volts ...

    ...but, as soon as you split that double pole 20 amp breaker into 2 separate 20 amp breakers on 120 volt circuit, you changed the entire equation.

    How? You ask ...

    Here is how:

    *IF* (and ONLY *IF*) those two 20 amp breakers remained in the same location (i.e., one on Phase A bus and one on Phase B bus) - then nothing changes - you essentially have (still have) a 240 volt load made up of balances 120 volt loads, with no neutral current.

    NOW *HOWEVER*, if you separate those two 2 amp breakers leaving one empty space between them, you have removed them from being on different phase legs and they are now on the same phase leg, making their currents additive *at 120 volts* instead of benefiting from having had them at 240 volts.
    Sigh back at you!
    Your ability to complicate simple answers is awsome. All some of the good folk here want to know is if it is possible to have 20 20-amp circuits and run 20 20-amp 120 volt toasters at the same time.

    So...just where did I suggest moving the breakers from their original position and putting them on the same leg? Do you really think I don't understand the difference?

    The difference between them and the 200 amp main is much more than "just times 10", the difference is that YOU CANNOT SEPARATE the 200 amp main into 120 volt legs ONLY - either BOTH will have the same current and the neutral will have no current (i.e., 200 amps maximum flowing through them), OR BOTH will have the same current as the lower one AND the neutral will have the current difference to the higher one (i.e., *less than* 200 amps flowing through them).
    Really? You seem to be saying that I couldn't disconnect one of the SEC's and then just use the one leg for my 10 20-amp ciircuits on that bus bar and power 10 20-amp 120-volt toasters. You're not? That would work? Well, OK...then when I reconnect the SEC to the other bus-bar can I, or can I not run an additional 10 20-amp toasters AT THE SAME TIME!!!

    YOU CANNOT SEPARATE the 200 amp main into 120 volt legs ONLY
    So...Yes I can! There is no functional difference between a 200-amp residential main and any other amperage double-pole breaker. If you don't believe that, then take a look at a Siemens/ITE quad main and then tell me there aren't separate, but linked, breakers for each side.

    Oh, and, don't forget, "*less than* 200 amps will still flow through a 200 amp main.
    OMG!!! Thank you for that enlightenment master!

    OK...that's it for me. I gave Tim a simple, understandable answer and I refuse to get sucked into this black hole any more. There was a thread entitled "What do you miss". Me, I miss the old Inspection News where normal HIs could continue normal HI discussions and one person didn't feel the need to dominate the board by disecting each and every damn thread and post for individual statements, usually completely out of context, he could disagree with. Yep....them were the good old days!

    I think I'm going to have to take a break from here for a while. It just isn't enjoyable anymore.


  36. #101
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    Default Re: Too much for 200A

    Congratulations Jerry,

    You wore another one down. One more victory for the pedant.

    Guess I'll copy all of this and send it to Mike Holt in an Email and ask him if he can tell me which one of these "explanations" I should believe.

    ONE TEAM - ONE FIGHT!!!

    Mike


  37. #102
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    Default Re: Too much for 200A

    Mike,

    I think everyone is in agreement with the theory now but for many its hard to overcome the tendency to total up 120V load amps and use that as the sole supply source. The center tap AC transformer is a really awesome thing when you think about it.


    It simply comes down to two ways to discuss it:


    If you choose to describe only max 120V loads, total current can be confusing and it is important not to use the wrong terminology.

    If you choose to describe the max supply source it is simple, 200A at 240V.


    This is the reason power is sold by the kw and not amps, we have two methods of getting power off residential service, at 120V or 240V.


    Its the power company not the amp company.


  38. #103
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    Default Re: Too much for 200A

    Quote Originally Posted by Jerry Peck View Post
    I have reduce all the above posts down to this one simple, easy to understand post, with one easy to understand question.

    SHOW ME THE 400 AMPS
    Jerry - This is for my benefit and for those who followed my revised discussion of the volts, amps, and power waves and current flow in post #86. Do you agree with this statement?:

    While it is possible to connect a bunch of 120V loads to a 200A 120/240V 1-phase 3-wire residential electrical system at the same time, and have the amp ratings of all of that 120V utilization equipment add up to 400 amps by simple addition of the amps on the nameplates on the equipment, if everything is wired and working properly, you should not measure more than 200A anywhere on the system.

    (I realize that instantaneous values of volts & amps fluctuate beyond 120/240 & 200 and those numbers represent "averages"... we are trying to keep it simple.)

    If not, how would you change it?

    Last edited by Brandon Chew; 04-06-2008 at 09:57 AM. Reason: add "If not...." sentence at end

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    Default Re: Too much for 200A

    Jerry agreed to all that several posts ago.


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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    400 light bulbs x 1 amp each = 400amps
    Nope, not when wired with 400 lamps with 200 sets of 2 lamps in series - that's only *200 amps*.

    No matter how you look at it, YOU WILL ONLY HAVE 200 AMPS when wired that way.

    You can call a duck a chicken as often as you want to, but to almost everyone else you will look silly when you point to a duck and say, with conviction, 'THAT is a *chicken*, no question about it.'

    Well ... they both do lay eggs, and the both do have feathers, and ... BUT, they are NOT one and the same thing.

    Jerry Peck, Construction / Litigation Consultant
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  41. #106
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    Default Re: Too much for 200A

    (underlining in the following quote is mine)
    Quote Originally Posted by Richard Moore View Post
    All some of the good folk here want to know is if it is possible to have 20 20-amp circuits and run 20 20-amp 120 volt toasters at the same time.
    Apparently not.

    That question has been answered numerous times.

    The answer is ALWAYS the same, and ALWAYS WILL BE the same.

    To wit: ONLY IF (don't you recall that from earlier posts ... *ONLY IF*) they are equally balanced between the phase legs.

    What is so hard to get about *ONLY IF*?

    As soon as one starts to talk about "*400 AMPS*" - which is really what this is all about ... a few (1 maybe 2 people) trying to insist that they are getting 400 amps - then everything changes.

    THERE ARE NOT 400 AMPS when wired as the question was asked. 200 AMPS, YES. 400 AMPS, NO.

    Whenever someone posts about 200 AMP, they are correct, and I state so, and agree ... but ... as soon as someone insists on calling it *400 AMPS*, that is incorrect and I say that too.

    Like it or not, the above is exactly what have been going on throughout this thread.

    ONE OR TWO PEOPLE INSISTING that there is 400 amps with wired as described - the rest which have posted acknowledge the difference ... those ONE OR TWO PEOPLE have not, and, apparently, will not, think it through or acknowledge the difference.

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  42. #107
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    Default Re: Too much for 200A

    Quote Originally Posted by Bruce King View Post
    Jerry agreed to all that several posts ago.
    Bruce, not all, as in "all", there are still one or two who have not yet "got it":

    Quote Originally Posted by Tim Voss View Post
    Thanks Richard, I did the math and it comes up to the controversial 400amps (at 120v). That's why I was really waiting to see what Jerry had to say.
    Quote Originally Posted by Tim Voss View Post
    400 light bulbs x 1 amp each = 400amps


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  43. #108
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    Default Re: Too much for 200A

    Quote Originally Posted by Brandon Chew View Post
    Do you agree with this statement?:

    While it is possible to connect a bunch of 120V loads to a 200A 120/240V 1-phase 3-wire residential electrical system at the same time, and have the amp ratings of all of that 120V utilization equipment add up to 400 amps by simple addition of the amps on the nameplates on the equipment, if everything is wired and working properly, you should not measure more than 200A anywhere on the system.

    ( ... we are trying to keep it simple.)

    If not, how would you change it?
    "If not, how would you change it?"

    Brandon,

    I would change it to read as follows:

    While it is possible to connect a bunch of 120V loads to a 200A 120/240V 1-phase 3-wire residential electrical system at the same time, you cannot simply add up the amp ratings of all of that 120V utilization equipment by simple addition of the amps on the nameplates on the equipment, if everything is wired and working properly, you should not measure more than 200A anywhere on the system. This is just like trying to add up the amp ratings for 6 mains in a service equipment panel - you cannot add up the amp ratings for 6 mains to get the amp rating of the service.

    Brandon, I believe that little bit of wording change in the middle of your statement, and the last sentence I added relating it to something which we all understand, makes it understandable for all and makes it work for all.

    None of us would walk up to a service equipment panel which has 6 - 100 amp mains and state that it is a 600 amp service, would we? Nor would we spend untold amounts of time trying to convince others that it was 600 amps.

    Anyone disagree with that?

    Anyone agree with that?

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  44. #109
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    Default Re: Too much for 200A

    And, last but not least ... well ... okay, he is least, so I responded last ..

    Quote Originally Posted by Michael P. O'Handley View Post
    Congratulations Jerry,

    You wore another one down. One more victory for the pedant.

    Guess I'll copy all of this and send it to Mike Holt in an Email and ask him if he can tell me which one of these "explanations" I should believe.

    ONE TEAM - ONE FIGHT!!!

    Mike
    Mike,

    If you got off your high horse (that tall statute horse covered with pigeon droppings) and actually read the posts, you would see that all ... *all* ... except ... yes, except ... except 1, possibly 2, are in agreement of what has been stated.

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  45. #110
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    Default Re: Too much for 200A

    Here is the correct formula for max service entrance load with 120V balanced loads.


    Using 400 one amp 120V lamps as the load (200 lamps per leg):


    400 x 1A / divided by 2 (since 1/2 of the loads are in series) = 200A.


  46. #111
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    Default Re: Too much for 200A

    Uh huh,

    Riiiigggghhhhhhhtt! That's why the thread went over a hundred posts.

    OT - OF!!!

    M.


  47. #112
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    Default Re: Too much for 200A

    Quote Originally Posted by Michael P. O'Handley View Post
    That's why the thread went over a hundred posts.

    Mike,

    Ummm ... YOUR post put it over 100 ... yours was #101.

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  48. #113
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    Default Re: Too much for 200A

    Interesting,

    Your last response is #112 on my display.

    Wonder if this will start another long debate wherein you try and convince me I don't know the difference between the numbers 101 and 112 ? LOL

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    Mike


  49. #114
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    Default Re: Too much for 200A

    Quote Originally Posted by Michael P. O'Handley View Post
    Wonder if this will start another long debate wherein you try and convince me I don't know the difference between the numbers 101 and 112 ?
    "wherein you try and convince me I don't know the difference between the numbers 101 and 112 ?"

    Ummm ... that long debate will only last until you learn to read ...

    See attached screen capture of your post, with the post number 101 encircled with an ellipse.

    You said: "That's why the thread went over a hundred posts."

    I stated: "Ummm ... YOUR post put it over 100 ... yours was #101."

    Review the screen capture and you will see who made the thread go over 100 posts - you did, with your post being the 101st post in the thread.

    Believe it or not, it's there for all to see.

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  50. #115
    Michael P. O'Handley's Avatar
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    Default Re: Too much for 200A

    LOL,

    Well, if I knew how to do a screen capture, I could show you that at this end your response is #114.

    Don't ask me why; maybe Brian knows.

    OT - OF!!!

    M.


  51. #116
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    Default Re: Too much for 200A

    I guess all those generator manufacturers are going to have to re-write their manuals, since they can't "really" power double the amount of 120v amps as 240v amps.

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  52. #117
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    Default Re: Too much for 200A

    OK,

    Sorry for the thread drift, but I finally figured out the screen capture thingy. As you can see, the posts are numbered differently than yours. What's up with that?

    OT - OF!!!

    M.

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  53. #118
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    Default Re: Too much for 200A

    Quote Originally Posted by Michael P. O'Handley View Post
    OK,

    Sorry for the thread drift, but I finally figured out the screen capture thingy. As you can see, the posts are numbered differently than yours. What's up with that?
    OT - OF!!!

    M.
    Ignore feature?


  54. #119
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    Default Re: Too much for 200A

    Quote Originally Posted by Michael P. O'Handley View Post
    As you can see, the posts are numbered differently than yours. What's up with that?
    "What's up with that?"

    You are looking at DIFFERENT POSTS - go back up and look at post number 100 (bottom of the first page), then look at post number 101 (top of the second page).

    WHO's post is post number 101?

    Hint: Yours.

    Thus, WHO's post caused this thread to go beyond 100 posts (which is what you were commenting on)?

    Hint: Yours.

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  55. #120
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    Default Re: Too much for 200A

    Wow, Jerry can count to a hundred.


  56. #121
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    Default Re: Too much for 200A

    Ok Jerry, so we disagree on how the amps of the loads may (or may not) add up.

    But you DO agree that you can put 120v loads whose "nameplate amps" add up to 400, on a 200a 240v service as long as the loads are perfectly balanced between the phases?


  57. #122
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    Default Re: Too much for 200A

    Jerry,

    You're a flaming jackass. Do you realize that? It doesn't matter who's post put it over 100, there wouldn't have been 100 posts about this in the first place, if you hadn't insisted on dissecting everyone's commentary, muddying the waters, and yammering on, and on, and on, and on, and on, and on......

    A horse's ass with teeth and a Napolean complex to boot; what a friggin putz!

    I need to unsubscribe to this place so I don't keep coming back here. Ta Ta!

    Never mind, I just found out how to turn on the ignore feature. That's pretty kewl. I think I'll add that at the crib.

    M.

    Last edited by Michael P. O'Handley; 04-07-2008 at 11:48 PM.

  58. #123
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    Default Re: Too much for 200A

    Quote Originally Posted by Michael P. O'Handley View Post
    Jerry,

    You're a flaming jackass. Do you realize that?
    Ohhh .... Mickie's hot now.

    First you try to blame someone else for making the thread go beyond 100 posts, then, when you find out it's you who did that, you try to re-direct your comment so you look innocent.

    You sure turned into a jackass ... wait, no ... you always were one, I will correct myself ... you sure exposed the real jackass you are.

    It doesn't matter who's post put it over 100, there wouldn't have been 100 posts about this in the first place, if ...
    ... you, Mike O', had not tried to insist your way was the right way, the only way.

    I need to unsubscribe to this place so I don't keep coming back here. Ta Ta!
    Now that's not a bad idea , it will save me from having to read your ignorant, intrusive and obnoxious posts.

    I don't use the ignore feature, I read what jerks like you write, and choose to ignore or to respond - that way I can track what jerks are saying what.

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  59. #124
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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    Ok Jerry, so we disagree on how the amps of the loads may (or may not) add up.

    But you DO agree that you can put 120v loads whose "nameplate amps" add up to 400, on a 200a 240v service as long as the loads are perfectly balanced between the phases?
    Tim,

    That's a poor way to state what you are trying to indicate (unless you are still trying to "add up to 400") because you are still "adding up" the "nameplate amps" as though that will work.

    In reality, you will need to "add up and divide out by the number of loads the same amps is flowing through" such the "nameplate amps" are no more than 200 amps are on the 200 amp 240 volt supply.

    You are still 'trying to "add up" the amps to get 400', and that does not work.

    Going back to my example of 6 mains, let's try this":

    Say you have 6 mains as follows"

    1 - DP 30 amp (DP stands for "double pole")
    2 - DP 60 amp
    2 - DP 100 amp
    1 - DP 50 amp

    Can you say that you can add those up 30 + 60 + 60 + 100 + 100 + 50 = 400 amps service?

    No, of course not, not anymore than you can add those 120 volt loads up to get 400 amps on a 200 amp 240 volt supply.

    You are close, but still not quite there.

    However, if you wanted to change your reference to 48,000 va of 120 volt loads on a 48,000 va 240 volt supply, then, yes.

    Jerry Peck, Construction / Litigation Consultant
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  60. #125
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    Default Re: Too much for 200A

    You may say it's a poor way to say it, but I don't think so.

    I'm trying to say how much 120v "stuff" I can plug into a 200amp 240v service. My devices have Nameplate ratings in 120v and amps. I want to make sure I don't overload the service. No division necessary, I just add up the Nameplate amp ratings of my 120v devices and as long as that is equal to or less than 400, everything is good. Right?


  61. #126
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    Default Re: Too much for 200A

    This is the part that is really killing me:
    However, if you wanted to change your reference to 48,000 va of 120 volt loads on a 48,000 va 240 volt supply, then, yes.
    Ok, I'll say 48,000 va of 120 volt loads. That is exactly what I'm saying. Let's just plug the 120 into the v and see what comes out for the a.


  62. #127
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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    Ok, I'll say 48,000 va of 120 volt loads.
    Then you would be correct, yes.

    That is exactly what I'm saying.
    Now, yes, but not before.

    Let's just plug the 120 into the v and see what comes out for the a.
    Not a problem, as long as you want to keep it all in the same context, however, that then does not go with the 200 amps 240 volts ... until you convert it to volt-amps. You still insist on mixing terms, and that does not work, not unless you want to spell out an equation or a problem. You either need to stick to volts and amps, or, volt-amps (watts).

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  63. #128
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    Default Re: Too much for 200A

    va is an equation, as in P=va

    That's a poor way to state what you are trying to indicate (unless you are still trying to "add up to 400") because you are still "adding up" the "nameplate amps" as though that will work.
    Are you saying that I can NOT put 400 Nameplate rated amps of 120v equipment on a 200amp 240v service?


  64. #129
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    Default Re: Too much for 200A

    Quote Originally Posted by Tim Voss View Post
    va is an equation, as in P=va
    No, va is only a statement, an equation needs all parts. If you noticed, "va" is simply "va", YOU ADDED the "P=" to make it an equation.

    Are you saying that I can NOT put 400 Nameplate rated amps of 120v equipment on a 200amp 240v service?
    Tim,

    I guess either you are just not paying attention, or I am just very poor at communicating this, but, here it goes for one more time:

    No, I am saying you cannot ADD THEM UP TOGETHER, which is what you continue to try to do.

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  65. #130
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    Default Re: Too much for 200A

    I'm not trying to add them up together. I'm trying to put twenty 20 Nameplate rated amp 120v toasters on the system. Are you saying I can't?


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