Results 66 to 130 of 266

08052013, 08:18 PM #66
Re: Determining the amperage mat a main disconnect fuse block
Thank you John for pointing out the math aspect of this issue and showing that two legs of 120 is the same capacity as one leg at 240.
Vern, look at the following link. Insert a 60 amp 120 volt load on both legs A and B of the panel and tell me where the current is flowing to. If you said the neutral you would be correct. Now how much is flowing through the main breaker. How much is flowing through breaker A, how much through breaker B? Answer 60 and 60.
http://www.samlexamerica.com/support...chCircuits.pdf
All answers based on unamended National Electrical codes.

08052013, 08:19 PM #67

08052013, 09:15 PM #68
Re: Determining the amperage mat a main disconnect fuse block
Just draw the circuit would you! Then you can put me out of my misery.
I was too quick to answer that! 120 volt loads on opposite legs will react as though they were 240 volt loads as far as current is concerned. So if the loads are balanced you will have the full wattage available, still only 60 amps total.
Last edited by Vern Heiler; 08052013 at 09:22 PM.
The beatings will continue until morale has improved. mgt.

08052013, 09:29 PM #69
Re: Determining the amperage at a main disconnect fuse block
First of all, as you indicated this is a multiunit (200  two hundred unit) apartment unit building AND that the main power feeder (not "service") is protected by a fuse block, it is highly unlikely that the power supplied is 120/240, and is most likely 208/120Y.
Furthermore since the most likely situation is that heat is supplied by other than pure electrical resistance heat, and that cooking is more likely to be supplied by other than electrical resistance coil  again multiphase for load diversity for the BUILDING SERVICE is the most likely, even with individual metered supplied by the utility.
Vern, you're getting yourself stuck on trying to apply DC electrical theory and a simple circuit for same and trying to apply (your "directional arrows on your 'diagram'") which doesn't "fly" with AC. Unlike DC current on a simple circuit with a purely resistive load, AC current doesn't flow "one way" from a positive battery terminal with a negative for reference  each conductor pulses the exchange in a "pull me/push me" fashion  on your scope you'll see a flat line for each half cycle for each conductor with center tap reference. Not all loads are purely resistive, in fact in todays "usual" residence with other than coil/resistive electric range, other than electric WH and other than electric resistive heat, few loads are "purely resistive". Modern electronics, including the electronics involved in compact fluo., televisions, etc. motor loads refrigeration, etc. multitude of rectiifiers & power supplies, none of which are purely resistive loads (most inductive, and PF increasingly "of issue") for large multiunit buildings.
Likely the main power feeder is 60 amps 208/120. IIRC the OP is in CT. Although early utility in No. NY and CT may have been DC "back in the day" the entire US has been on a 60 Hz AC standard for over a century (for other than RR, aircraft & marine) and Con Ed does not supply DC power to residential occupancies.
Be that as it may, there is no way the load side feeder from the fuse block to the residential unit can be called a "service". Presuming it is a dedicated feeder and not a polyphase riser tapped or fedthrough, at best it could be called a "main power feeder" for the occupancy.
I don't recall the OP having indicated the "meters" were "utility owned and/or controlled" for that matter either, not that it matters.
60 amp fuse on each of two split halfphase legs is still a 60 amp supply (and likely each are split half phases from polyphase supply) The "Service point" before the feeder to the unit not in the unit.

08052013, 09:29 PM #70
Re: Determining the amperage mat a main disconnect fuse block
If it was drawn it would not make it true. Each breaker or fuse will add capacity. Since there are two legs able to supply 7200 watts each, the total capacity of the service is 14,400 watts. (60*120)=(7200) *2 = 14,400 watts.
Vern, pull one of the fuses out of the block and tell me how many amps can flow through the remaining leg. How many legs can support that current? How many amps can flow through both legs?
All answers based on unamended National Electrical codes.

08052013, 09:33 PM #71
Re: Determining the amperage mat a main disconnect fuse block
Did you read this part? "The maximum current flowing in the common Neutralwill be limited to the breaker capacity (Maximum current will flow in the common Neutral when one of the split phase branch circuitsis not loaded
and the loaded split phase branch circuit is drawing itsfull rated capacity)."
The beatings will continue until morale has improved. mgt.

08052013, 09:43 PM #72
Re: Determining the amperage at a main disconnect fuse block
Who cares what the voltage is? The question was how much power could be supplied through a 2 fuse 60 amp pullout disconnect. Stick to the subject and stop speculating.
Furthermore since the most likely situation is that heat is supplied by other than pure electrical resistance heat, and that cooking is more likely to be supplied by other than electrical resistance coil  again multiphase for load diversity for the BUILDING SERVICE is the most likely, even with individual metered supplied by the utility.
   Updated   
Correct, the neutral current will never be more than the ungrounded current in a MWBC. If only one leg is flowing the maximum current and the other leg is flowing 0, the current on the neutral is still limited to the breaker maximum.
Where do you think the extra current would be coming from?
All answers based on unamended National Electrical codes.

08052013, 09:45 PM #73
Re: Determining the amperage at a main disconnect fuse block
H.G. If you can get current to flow in two directions at the same point in time in the same conductor you will be the first to do so. The potential difference along the secondary at any point in time is +++ and it could be a series of batteries for that point in time.
The beatings will continue until morale has improved. mgt.

08052013, 10:00 PM #74
Re: Determining the amperage at a main disconnect fuse block
"Where do you think the extra current would be coming from?"
That was my question to you, I've always said 60 amps is the maximum. Where do you think the sixty first amp comes from? (And I diagrammed my current flow)
The beatings will continue until morale has improved. mgt.

08052013, 10:07 PM #75
Re: Determining the amperage mat a main disconnect fuse block
Sixty amps is able to flow through each fuse. You have two fuses. How much is 2 x 60?
Lets try this another way again. Say you have 1500w toaster oven on leg A and are warming dinner. Now you also want a cup of coffee and start your 1500w coffee maker that is on leg B. How many amps are being used, 12.5 or 25 amps?
All answers based on unamended National Electrical codes.

08052013, 10:15 PM #76

08052013, 10:23 PM #77

08052013, 10:26 PM #78
Re: Determining the amperage mat a main disconnect fuse block
You didn't answer the question. How many amps are being used by the two 1500 watt appliances?
All answers based on unamended National Electrical codes.

08052013, 10:29 PM #79
Re: Determining the amperage mat a main disconnect fuse block
The beatings will continue until morale has improved. mgt.

08052013, 10:33 PM #80

08052013, 10:41 PM #81
Re: Determining the amperage mat a main disconnect fuse block
Here's an attempt to explain why you can get 120 amps from two 60 amp fuses. To explain this I will use as an example a double pole 60 amp circuit breaker. We know this breaker is connected to both legs in the panel. We also know the voltage will be 240 volts AC across the legs. Now we put a 60 amp load on the breaker. Follow me Vern? Good! If you calculate the voltage by the amperage, (240 volts x 60 amps = 14400 watts). The panel doesn't give a hoot that I'm using a two pole breaker that's connected to both legs. The fact is I'm consuming 14400 watts. Am I still good Vern. OK. Now, we know we can only get 60 amps from one leg and we know this leg gives us 120 volts in respect to neutral. this calculated out (60 amps x 120 volts = 7200 watts). Say what? 7200 isn't very good, we need 14400 watts. So where do we get the other 7200 watts to make 14400 watts? Lets use both legs. LEG A (60 amps x 120 volts = 7200 watts + LEG B (60 amps x 120 volts = 7200 watts)). Fact, we have 7200 watts available on each leg. Fact, if we use both legs to feed the double pole circuit breaker we will have 14400 watts total. Here is the proof your looking for. The proof is we can add together the current on each leg to achieve the 14400 watts we need. there is no dispute about this. Its real, its fact, its true. But, if this is possible, that means each leg must be compatible to be use this way. It must also mean each leg is independent of each other. So how do we have independent legs coming from the same source? The answer is the legs are out of phase. As a matter of fact, there 180 degrees out of phase. Perfect. This works and I proved it. Now, its fact we have 7200 watts per leg. Calculating this out works like this, (7200 watts / 120 volts = 60 amps). If we can add leg A to leg B for a sum of 120 amps, there MUST be 60 independent amps per leg. They MUST be compatible to work together. And in fact, if we use both legs regardless of anything else, there is useable, consumable, and undisputable 120 amps available. A sixty amp, 240 volt panel has 120 amps to be used as we see fit which is the same as saying a sixty amp 240 volt circuit breaker can supply 14400 watts. Each leg supplies 60 amps, independent of each other, without interfering with each other, with out relying on each other. I proved it earlier in this post. A drawing or diagram isn't necessary. Its simple math. Please except this as a vial, friendly explanation to help you understand.
   Updated   

08062013, 05:51 AM #82

08062013, 06:01 AM #83
Re: Determining the amperage mat a main disconnect fuse block
"So how do we have independent legs coming from the same source? The answer is the legs are out of phase. As a matter of fact, there 180 degrees out of phase. Perfect."
Mike, what you are describing is the voltage in reference to neutral, not the current. If you have a 240 volt panel, no neutral is required and the voltage across the two legs is in phase, do you think you reverse half of the current just because you put a neutral in? Doesn't happen!
The beatings will continue until morale has improved. mgt.

08062013, 06:42 AM #84
Re: Determining the amperage mat a main disconnect fuse block
Took awhile to find this from a member from here. Haven't seen Roger here in a few years.
All answers based on unamended National Electrical codes.

08062013, 06:52 AM #85
Re: Determining the amperage mat a main disconnect fuse block
The beatings will continue until morale has improved. mgt.

08062013, 07:00 AM #86
Re: Determining the amperage mat a main disconnect fuse block
Last edited by Jim Port; 08062013 at 07:12 AM.
All answers based on unamended National Electrical codes.

08062013, 07:18 AM #87
Re: Determining the amperage mat a main disconnect fuse block
It shows 10a on one leg and 5a on the other leg with 15a on the neutral. Just bump the numbers up to 60a on each leg and tell me what is on the neutral. And they can't go in both directions at the same time on the neutral.
The beatings will continue until morale has improved. mgt.

08062013, 07:30 AM #88
Re: Determining the amperage mat a main disconnect fuse block
The diagram clearly states in the box that the neutral is carrying 5 amps, the difference between the 10 on A and the 5 on B.
Simplify this, draw two independent 60 amp 120 volt circuits, each with a neutral. You now have 2 hots (ungrounded) and two grounded conductors. How much current can flow through one hot? How much can flow through the other hot? What is the combined current through both hots at 120 volts? Can you turn off either hot without affecting the operation of the other circuit?
Last edited by Jim Port; 08062013 at 07:31 AM. Reason: spelling
All answers based on unamended National Electrical codes.

08062013, 07:37 AM #89
Re: Determining the amperage at a main disconnect fuse block
If both legs are carrying 60 amps or any other balanced value and are on opposing legs, the neutral is carrying 0. The opposing currents offset each other. This is why the neutral does not need to be twice as large as the ungrounded conductors.
All answers based on unamended National Electrical codes.

08062013, 07:54 AM #90
Re: Determining the amperage mat a main disconnect fuse block
Um, no! It shows 10a going from right to left and 5a going from left to right on the same wire.
The beatings will continue until morale has improved. mgt.

08062013, 08:01 AM #91
Re: Determining the amperage at a main disconnect fuse block
Jim, can you dispute anything on the last drawings I posted. Does the current go in the same direction on the wires at any given point in time. Does the current going in equal the current coming out.
Your biggest problem is mixing current and voltage. The 180 phase shift in your diagram is voltage. The voltage is more positive than the neutral on top and less positive on the bottom, but all one single current has developed the potentials. Its just that we are measuring from the middle to the ends.
The beatings will continue until morale has improved. mgt.

08062013, 08:02 AM #92
Re: Determining the amperage mat a main disconnect fuse block
Those are the opposing amplitudes and are subtractive, not additive.
Please answer the questions I posted above. If you do the math correctly you should come up with the same answers as myself, Robert M, John P and Mike.
I really want to hear you explain what the affect of turning off one leg has on the other.
If you had a 2" hose connected to Hoover Dam and added another 2" hose would you get the same amount as the single hose? Same concept.
All answers based on unamended National Electrical codes.

08062013, 08:23 AM #93

08062013, 08:29 AM #94
Re: Determining the amperage mat a main disconnect fuse block
I'm not about to choose a side, but you guys are to be commended.
Nearly 100 post on this and no name calling, slanders, or put downs.
' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

08062013, 01:52 PM #95
Re: Determining the amperage mat a main disconnect fuse block
Vern, sorry to see that you could not see the facts regardless of the examples presented or by whom. If you had looked at this as 2 parallel 120 circuits it would have been easy to see how to have 120 amps available through the disconnect. The math was shown several times.
All answers based on unamended National Electrical codes.

08062013, 02:32 PM #96
Re: Determining the amperage mat a main disconnect fuse block
The beatings will continue until morale has improved. mgt.

08062013, 03:03 PM #97
Re: Determining the amperage mat a main disconnect fuse block
Ignore the transformer and focus on 2 60 amp single pole circuits. Each can flow 60 amps. You say you can understand the math, but cannot accept that 60 x 2 = 120?
All answers based on unamended National Electrical codes.

08062013, 03:16 PM #98

08062013, 03:25 PM #99

08062013, 10:16 PM #100
Re: Determining the amperage mat a main disconnect fuse block
This is as simple as it gets. I'm having a real hard time you don't see this. Each load can take 60 amps. I'm going to word this very carefully. In reference to the second drawing  This is what exists in a main pannel less the transformer. The secondary of the transformer with a center tap makes two 120 volt individual circuits both providing 60 amps in reference to the center tap / neutral or ground. The center tap is essential for creating two seperate 60 amp supplies. Please note the word seperate. Seperate means not of the same body, individual, not together. Each leg in the main panel is powered by is own power source in reference to neutral which means they are individual sources seperate from each other. Not of the same body, individual, not together. Each source supplies 60 amps. There are two seperate sources. 60 amps on leg A and 60 amps on leg B. I can put a load on leg A of 60 amps. I can also put a load on leg B of 60 amps. The total amount of amperage I can load from the panel is 120 amps. Please read and think about the last statement. The total amount of amperage I can load from the panel is 120 amps. Not from each leg, The panel. The total load of both legs. Your drawings are nonsense. You show series resistance and label each one 60 amps. Your diagrams relate more to DC then AC. The arrows show DC paths. Its sad that you are so obstinate in trying to prove something that is wrong instead of listening to what others are telling you, or you just don't understand whats being said. This is not criticism but If you truly believe everyone who posted there response is wrong, I suggest you consult a professor or engineer in the electrical field (not an electrican) with your drawings and get a second opinion before producing any more arguments to your beliefs.
Last edited by Mike Borchardt; 08062013 at 11:54 PM.

08072013, 05:07 AM #101
Re: Determining the amperage mat a main disconnect fuse block

08072013, 05:58 AM #102
Re: Determining the amperage mat a main disconnect fuse block
Have enjoyed the pingpong match.
Have a few questions for you guys.
1) How do you typically name the service cable AWG 4/3 coming from the triplex connection to the meter ? ____________________.
2) How would you describe a service cable that was AWG 4/2 ? ______________
3) Using the answer from question # 1 . What is the total number of Amps that the service can supply? ___________
4) Using the answer from question #2 . What is the total number of Amps that the service can supply? ___________
5) If you had two separate service panels and each was serviced by only one leg of a 4/3 service cable how many Amps would each box be able to supply ? ___________________
6) If a property needed 128 Amps to satisfy the the load.
__A) What would you expect to see as a service cable ?___________
__B) What would you expect to see as a main service panel ? ___________________
__C) How many and what size breaker would you to find ? _____________

08072013, 08:27 AM #103
Re: Determining the amperage mat a main disconnect fuse block
I understand your frustration.
The beatings will continue until morale has improved. mgt.

08072013, 09:34 AM #104

08072013, 01:18 PM #105
Re: Determining the amperage mat a main disconnect fuse block
I will have to say you have a lot of staying power. No one will ever produce a diagram or the math that will show the 120 amps exists because there isn't any such animal. I wonder if they balance their bank account using the same math Probably why this countries' banking system is in such a mess..
"Get correct views of life, and learn to see the world in its true light. It will enable you to live pleasantly, to do good, and, when summoned away, to leave without regret. " Robert E. Lee

08072013, 01:53 PM #106
Re: Determining the amperage mat a main disconnect fuse block
Roland the math and how you could get 120 amps from that panel was described numerous times in this thread. That panel can supply 120 amps at 120 volts or 60 amps at 240 volts. Use Ohms Law and you will see how it is the same amount of watts.
One circuits ability to flow current does not affect another circuit. If it did you would be limited to whatever the smallest circuit breaker installed was. I have asked VH to explain how he thinks it is possible, but so far he has not answered the question. He also could not add up the amps flowing on 2 single pole circuits and get the correct answer.
All answers based on unamended National Electrical codes.

08072013, 03:11 PM #107
Re: Determining the amperage mat a main disconnect fuse block
I know what you mean!! This discussion was never about power or watts or voltamps. It was about whether you can get 120 amps from 2 60 amp breakers on opposite phases. The answer is no and will remain no even to "those who cannot grasp the simple concept". Whan the direct question was asked about whether or not everyone wanted to talk about watts, etc. There was no clear answer. Only repeating that the 120 amps was valid. No one here can draw a circuit, calculate or measure 120 amps from a 60 amp service..
"Get correct views of life, and learn to see the world in its true light. It will enable you to live pleasantly, to do good, and, when summoned away, to leave without regret. " Robert E. Lee

08072013, 03:20 PM #108
Re: Determining the amperage mat a main disconnect fuse block
I apologize for continuing this so long. I was hoping to use this as a teaching moment and that the students would finally grasp the subject and understand what they were missing. Oh well, you can't reach everyone. Sad.
I should have realized that some were not getting it when the load of 2 12.5 amp circuits still equaled 12.5 amps.
All answers based on unamended National Electrical codes.

08072013, 03:29 PM #109
Re: Determining the amperage mat a main disconnect fuse block
Let me put into dollars since everyone should under stand money.. You put $60 into your account (or pocket) you immediately take $60 dollars out for something. Some of you would reach in your pocket and expect to find 120 dollars. The net result is 0 dollars. Same math with this circuit..no 120 amps anywhere...because it is additive using "absolute" values. Try putting it on a number line and move your finger back and forth, it will never spike up to 120..
And some are trying to confuse the issue by saying this is not a DC circuit and its not but it doesn't make any difference. It would work with AC or DC.
"Get correct views of life, and learn to see the world in its true light. It will enable you to live pleasantly, to do good, and, when summoned away, to leave without regret. " Robert E. Lee

08072013, 03:54 PM #110
Re: Determining the amperage mat a main disconnect fuse block
I would ask those that believe that there is only 60 amps available from that panel to post the same question asked the same way on an electrical forum and post a link to that discussion.
All answers based on unamended National Electrical codes.

08072013, 06:03 PM #111

08072013, 07:46 PM #112

08072013, 08:02 PM #113
Re: Determining the amperage mat a main disconnect fuse block
And my answer is: The problem is about apples. Why is someone introducing a question about oranges? The question Jim is referring to is about oranges. The source and the circuit was sufficiently defined early on so lets try to answer that question before moving on. The question (as a reminder) is about a single phase, 120/240 volt service with 60 main. How many amps is the maximum at any time? Not watts, not VA not all on the same phase.....or for those of you who are stuck, draw, measure or calculate it to prove it will be 120 amps. (you can't BTW)
Oh and BTWthe answer is +60 and (60). Because when one phase is positive the other is negative. It does not add up to 120 amps. Never more than 60..
The wattage (VA) is positive in both cases because VA=E x I and VA= (E) x (I) both positive answers. Basic 5th grade math. but we are not talking about this..
"Get correct views of life, and learn to see the world in its true light. It will enable you to live pleasantly, to do good, and, when summoned away, to leave without regret. " Robert E. Lee

08072013, 09:02 PM #114
Re: Determining the amperage mat a main disconnect fuse block
Again the concept that each leg at 120 volts can supply 60 amps eludes.
Thankfully the electricians understand this.
Could you answer Roberts question above above the two 20 amp breakers on the same leg?
All answers based on unamended National Electrical codes.

08072013, 09:55 PM #115

08072013, 11:08 PM #116

08082013, 02:59 AM #117
Re: Determining the amperage mat a main disconnect fuse block
Congratulations, you finally see using Diagram 1 that it is possible to flow 120 amps @ 120 volts.
All answers based on unamended National Electrical codes.

08082013, 06:08 AM #118
Re: Determining the amperage mat a main disconnect fuse block
The beatings will continue until morale has improved. mgt.

08082013, 06:31 AM #119
Re: Determining the amperage mat a main disconnect fuse block
Not exactly breaking news or a fire hazard, single pole circuits have operated safely like that for years.

08082013, 06:45 AM #120

08082013, 06:58 AM #121
Re: Determining the amperage mat a main disconnect fuse block
Because the hots are from opposing legs of the panel they would only carry the difference between the two hots, not the sum of the hots. Every single phase 120/240 panel operates the same way. The service is one large multiwire circuit.
All answers based on unamended National Electrical codes.

08082013, 07:09 AM #122
Re: Determining the amperage mat a main disconnect fuse block
"Get correct views of life, and learn to see the world in its true light. It will enable you to live pleasantly, to do good, and, when summoned away, to leave without regret. " Robert E. Lee

08082013, 07:14 AM #123
Re: Determining the amperage mat a main disconnect fuse block
One of the principles I have learned over the years in Math, Electrical Engineering and teaching is you must keep track and do the math operations on the unit labels all the way through the problem or the answer will be meaningless as it this example. I have also learned the you can't mix apples and oranges to come up with something of meaning such as in a lot peoples thinking here. And I have also learned that a politician is always right even when they are wrong . They just have to convince a lot of people they are right...(doesn't make them correct)...
"Get correct views of life, and learn to see the world in its true light. It will enable you to live pleasantly, to do good, and, when summoned away, to leave without regret. " Robert E. Lee

08082013, 07:45 AM #124
Re: Determining the amperage mat a main disconnect fuse block
The beatings will continue until morale has improved. mgt.

08082013, 07:54 AM #125
Re: Determining the amperage mat a main disconnect fuse block
I think it is interesting how you try to convince everyone there is 120 amps somewhere and then you post this in complete disagreement with yourself???? I think you have confused yourself.
   Updated   
If the diagram with this post was mathematically correct (valid) you should be able to hook this circuit up in the lab and measure 120 amps on the neutral. And that won't happen cause it will be 0 amps when they are combined.
   Updated   
Yes, You have it nailed. When you don't understand the whole package it is impossible to analyze it..
"Get correct views of life, and learn to see the world in its true light. It will enable you to live pleasantly, to do good, and, when summoned away, to leave without regret. " Robert E. Lee

08082013, 07:59 AM #126
Re: Determining the amperage mat a main disconnect fuse block
"Get correct views of life, and learn to see the world in its true light. It will enable you to live pleasantly, to do good, and, when summoned away, to leave without regret. " Robert E. Lee

08082013, 08:06 AM #127
Re: Determining the amperage mat a main disconnect fuse block
In the 120 volt circuits there are two ungrounded conductors, one for each circuit carrying 60 amps.
Last edited by Jim Port; 08082013 at 08:15 AM.

08082013, 08:46 AM #128

08082013, 08:51 AM #129
Re: Determining the amperage mat a main disconnect fuse block

08082013, 08:58 AM #130
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