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  1. #1
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    Default Electric Panel Service Amps, Was my inspector wrong?

    I know nothing about this stuff having just bought my first house after renting all my life. My inspector told me I had a 70 amp panel which was about overamped as it was and needed to be replaced soon after moving in, especially before installing AC.

    I mentioned this to first AC consult I got, he agreed, but then continued to quote me $3k for the panel and $5500 for a 3 ton goodman AC unit, which seemed ridiculous to me so if he was purposely misrepresenting my panel because he likes to gouge people I wouldn't be surprised.

    Second AC consult I got told me just today it's a 150 amp panel and it'll be totally fine.

    So now I'm stuck with looking at it myself (or hiring an electrician to literally look at my panel for 2 minutes which seems ridiculous) and looking at it myself I can't agree that it's 70 amps, but I'm not sure if it's 150 amps either.

    So in short, can anybody tell me what my service is based on some pictures I've taken?

    I see a few discrepancies, one is the diagram on the box shows a panel with 14 breakers, but the panel shows spots for 20. So is the panel an upgrade over the original boxes panel such that the diagram is out of date?

    The other is the 70 amp number appears on the diagram as max branch breaker amperage, which reads to me as meaning I can have no breaker of greater size than 70 amps, but it says main breaker size of 100 amps, and then under "main ratings" it says 125 amps. Which of these numbers means what, I have no idea.

    Unfortunately it lacks a main breaker, therefore I have to guess my maximum service based on the available info as well as looking at the conduit of which there are 2 and a ground, and the meter (which I can find no identifying information on regarding amperes). The conduit appears to my eyes based on the images at Electrical wire sizes & Diameters: table of Electrical Service Entry Cable Sizes & Ampacity - Electrical capacity or size: How to estimate the electrical service ampacity and service voltage entering a building by visual inspection - photographs and to be *at least* a 1 AWG which I'm guessing the 2 conduits is not running cumulative but rather bidirectionally giving me a max conduit of 200 amps according to the linked website, though again I am now clearly far beyond my experiantial knowledge on anything here.

    So in short, here's some pictures, help.






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  2. #2
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Difficult for me to want to answer someone who does not use their real name.

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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    50 + 30 + 50 = 130 which exceeds mains max 125A, that's your panel only ? so the "panel over amped" yeah.

    But you have other issues which further are limiting in safe capacity and are additionally exigent; for example size and type of conductors, deterioration, corrosion, breaker type, installed where, shared neutral terminations with multiple (some undersized AL) grounds, installed where, etc.

    I'm having a difficult time believing that the HI "said" what you said, or that's "how" he/she said it. Asking a HVAC tech for an electrical est. - silly.
    Get a licensed electrical contractor or two or three, in there and get valid review, clear scope of work and valid estimates. You'll need the details for the AC system of choice so proper load calcs can be performed and a clear scope of work can be outlined and priced out.

    Quote the actual report language from the Home Inspector's Report (if there was one - not just a HUD appraisal) instead of sumarizing what you "understood" the HI to "say".

    Jimmy Hoffa lives, huh?

    Last edited by H.G. Watson, Sr.; 09-10-2013 at 11:12 PM.

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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Gunnar Alquist View Post
    Difficult for me to want to answer someone who does not use their real name.
    Do we really know if people here are using their real names, or one plucked from the phone book ??


  5. #5
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    You may want to consider adding a sub panel. It looks like you're out of 240 volt spaces in that panel. That could solve several problems for you. The home inspector did tell you that you had aluminum branch circuits, I hope.

    Jim Robinson
    New Mexico, USA

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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by jack davenport View Post
    Do we really know if people here are using their real names, or one plucked from the phone book ??
    You have a good point "jack davenport".

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  7. #7
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    What you have there is a split buss panel, where only part of it has a main breaker. Anorm for the 70s and 80s. What will determine the amperage will be the gauge of the service conductors. A #2 aluminum is a norm for a 100 amp residential service.

    Now, what prevents those conductors from being overloaded is a load calc, ie a calculation done by the electrician that makes sure worst case scenario it doesn't overload when running a lot of stuff, but usually its not a problem for smaller houses even with ACs. Again, load calc is what prevents more being put on the panel than it can handle.


    Now as for the split buss design its no longer made for 2 reasons. 1, the top breakers can not exceed 6 in number. The reason being you cant flip more than 6 breakers to kill power to the whole house. problem with that is people would put more than 6 at the top. Second if someone did overload the panel there is no main breaker to trip. But when done right these split buss panels are not an issue. Hundreds of thousands still exist most with no problems at all.

    From the looks of it that panel does not need to be replaced.

    Last edited by Mbrooke; 09-13-2013 at 08:51 AM.

  8. #8
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by H.G. Watson, Sr. View Post
    50 + 30 + 50 = 130 which exceeds mains max 125A, that's your panel only ? so the "panel over amped" yeah.

    Jimmy Hoffa lives, huh?

    That means nothing. I can count the breakers in any panel and 90% of the time it exceeds the main feeder or the buss rating sometimes by 5 fold. Local commercial building near by has a 6 throw main, utility feed and switch gear buss bars are rated 2000amps max, total breaker counts hover around 3000amps. It was done all the time and still is in commercial/industrial.

    I dont believe that service is an issue. It looks untouched from the original install. If those main conductors are #2 which is my bet than its a 100 amp service. Smaller or larger will dictate if its less than 100amps or up to the max of 125. If the major loads are limited, ie only the dryer and oven are electric and house is 1500sq feet; then a 2.5 ton AC and an AHU should not be a problem. If the house is all gas AC could be 6 tons easy. But the final factor to determine an over amp would be a load calc, which I don't think would be exceeded here.

    I would however be way more concerned about the single stranded aluminum wires.


  9. #9
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Mbrooke View Post
    What you have there is a split buss panel, where only part of it has a main breaker. Anorm for the 70s and 80s. What will determine the amperage will be the gauge of the service conductors. A #2 aluminum is a norm for a 100 amp residential service.

    Now, what prevents those conductors from being overloaded is a load calc, ie a calculation done by the electrician that makes sure worst case scenario it doesn't overload when running a lot of stuff, but usually its not a problem for smaller houses even with ACs. Again, load calc is what prevents more being put on the panel than it can handle.


    Now as for the split buss design its no longer made for 2 reasons. 1, the top breakers can not exceed 6 in number. The reason being you cant flip more than 6 breakers to kill power to the whole house. problem with that is people would put more than 6 at the top. Second if someone did overload the panel there is no main breaker to trip. But when done right these split buss panels are not an issue. Hundreds of thousands still exist most with no problems at all.

    From the looks of it that panel does not need to be replaced.


    Quote Originally Posted by Mbrooke View Post
    Quote Originally Posted by H.G. Watson, Sr.
    50 + 30 + 50 = 130 which exceeds mains max 125A, that's your panel only ? so the "panel over amped" yeah.

    Jimmy Hoffa lives, huh?

    That means nothing. I can count the breakers in any panel and 90% of the time it exceeds the main feeder or the buss rating sometimes by 5 fold. Local commercial building near by has a 6 throw main, utility feed and switch gear buss bars are rated 2000amps max, total breaker counts hover around 3000amps. It was done all the time and still is in commercial/industrial.

    I dont believe that service is an issue. It looks untouched from the original install. If those main conductors are #2 which is my bet than its a 100 amp service. Smaller or larger will dictate if its less than 100amps or up to the max of 125. If the major loads are limited, ie only the dryer and oven are electric and house is 1500sq feet; then a 2.5 ton AC and an AHU should not be a problem. If the house is all gas AC could be 6 tons easy. But the final factor to determine an over amp would be a load calc, which I don't think would be exceeded here.

    I would however be way more concerned about the single stranded aluminum wires.
    You don't know what you are talking about regarding "50A + 30A + 50A = 130A" being relavent, and are completely WRONG in your ignornant declaration: "That means nothing"regarding the OP's title subject and his post! YES those current limiting MAINS devices ARE ADDED to determine the limiting cumulative total to determine the maximum rms current the service conductors (if they are indeed service disconnects) may be "called upon to draw" from the loads sourced from THIS PANEL, for a "service" and in the absence of any (upstream, or line-side, or "origination side of the supplying conductors prior to entering this panel and landing upon the MAINS LUGS) line-side current limiting device(s) of lesser capacity than 130A (such as a fuse block, a 2-pole (non-delta) circuit breaker, etc.),

    The MAINS are lugged and the upper (MAINS BUS) contains three sets of pole current-limiting devices. This panel does not have a single MAINS breaker or a singluar common-trip two pole protection - it has THREE sets of two-pole protection, comprised of four "devices" two of which are tied.

    The pair of 50 A breakers, the 30A 2-pole and the 50 A "main" for the SUB-BUS ARE the MAINS stabs. Those three 2-pole each sets ARE the series parallel "protection" for the MAINS (not "main"). The rated maximum for the MAINS lugs and the MAINS bus(es) IS 125A, the MAINS are "over amped" in the language of the OP.

    The lower "MAIN" 50A circuit breaker is not the "MAINS" circuit breaker for the panel, it is the "main" supply and feed-through and protection for the "SUB" Bus(es) (the "hot" bus(es) functions similarly to that of a "sub" panel; that back-in-the-day did not require isolation of N & G load-side of the "service equipment").

    The sub-bus feed-through is rated to a limitation of 100A max. That "main" circuit breaker "feeding" the sub-bus(es) up on the Mains Bus is required to be no more than 100A (100% feed-through - which is 80% of 125A - or the inverse 100A x 125% = the max rating for the entire panel, the mains lugs and the mains bus(es). hting main is not subject to the other more limiting "Stab" limitation of this panel (70A), however IT and the use of numbered positions 1 & 2 (mains top left and right) are subject to a combined limit total of 125A (mains lug "maximum" and overall panel "maximum" limitation )

    Those 120V 15 & 20A circuit breakers have nothing to do with the "Service" amperage current limitation "answer" to the OP's question(s).

    The three sets of circuit breaker poles I mentioned are the MAIN DISCONNECTS (plural) for the load-side of the supplying conductors' energy from the MAINS BUS(es) supplied via the MAINS LUGS of this panel.

    The OP's panel includes 15 & 20 amp circuits which employ solid aluminum wiring, some of which have undersized neutrals, and some of which has a grounding conductor, solid aluminum of which are under-sized. Several (3 I counted) of the conductors ( have been "attached" incorrectly to the N bus (wrapped under screw heads not inserted through terminals).

    The present current limiting devices installed upon the MAINS equal 130A (pair of tied 50A poles plus 30A 2-pole common trip plus the 50A common trip supplying the sub-main bus (containing 15 & 20 A single pole breakers). That equates to being "over-amped" at 5 A beyond the rated max for the mainS lugs and the MAINS Bus which was rated and required to be current limited to no MORE THAN 125 A.

    Unless the supplying conductors to this panel are line-side limited (ahead of this panel's MAINS LUGS) at 125A or less, the panel IS INDEED (again in the OP's language) "Over-amped".

    Whether or not there exists companion service equipment (another service panel in addition) is UNKNOWN. Whether or not THIS equipment is actually "the" (solitary) "service equipment" vs. "feeder" equipment is likewise unknown.

    As far as your assertion that the panel "looks untouched since its original instal" There are obvious indications that the opposite is true.

    The conductors (wires) which are NOT STRANDED are refered to as SOLID (wire) conductors, NOT "single stranded".

    The vintage aluminum sold wire brnch wiring is an issue regarding maintenance, safety caution, and insurability. There are numerous issues with this equipment and installtion which require competant remediation and most certainly prior to any DIY attempts by the OP to expand, extend, increase, maintain, correct or re-work the wiring system.

    Of special note the OP selectively did not share a photo with the deadfront cover in place. Perhaps had he, you might have picked up a clue or two.

    Last edited by H.G. Watson, Sr.; 09-13-2013 at 12:51 PM.

  10. #10
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by H.G. Watson, Sr. View Post
    You don't know what you are talking about. YES those current limiting MAINS devices ARE ADDED to determine the limiting cumulative total to determine the maximum rms current the service conductors (if they are indeed service conductors) may be "called upon to draw" from the loads sourced from THIS PANEL, for a "service" and in the absence of any (upstream, or line-side, or "origination side of the supplying conductors prior to entering this panel and landing upon the MAINS LUGS) line-side current limiting device(s) of lesser capacity than 130A (such as a fuse block, a 2-pole (non-delta) circuit breaker, etc.),

    The MAINS are lug only and the upper (MAINS BUS). This panel does not have a single MAINS breaker or two pole protection - it has THREE sets of two-pole protection, comprised of four "devices" two of which are tied.

    The pair of 50 A breakers, the 30A 2-pole and the 50 A "main" for the SUB-BUS ARE the MAINS stabs. Those three pole sets ARE the series parallel "protection" for the MAINS (not "main"). The rated maximum for the MAINS lugs and the MAINS bus(es) IS 125A, the MAINS are "over amped" in the language of the OP.

    The lower "MAIN" 50A circuit breaker is the "MAIN" circuit breaker and protection for the "SUB" Bus(es) (the "hot" bus functions similarly to that of a "sub" panel; that back-in-the-day did not require isolation of N & G load-side of the "service equipment").

    The sub-bus is rated to a limitation of 100A max. That "main" circuit breaker "feeding" the sub-bus(es) up on the Mains Bus is required to be no more than 100A (at 100% continuous duty) so as to protect the "exposure" of the MAINS Lugs and MAINS BUS(es) supplying it to its maximum limitations of the MAINS lugs & Bus(es) AS Lighting loads are calculated as CONTINUOUS and therefore derated limitation of that combined load for continuous is x 80%, or for the inverse you take the value and multiply it by 125%, therefore the "load" drawn to the sub-bus at 100A continuous is multiplied by 125% which is the maximum load current rated for the SUPPLYING structure. Therefore if the Sub-bus supplying "MAIN" Circuit breaker (second down on left 50A 2-pole common trip 120/240 breaker, without a numbered panel position in the wiring diagram/schematic) were to be RATED at 100% capacity and the maximum permitted installed value (100 Amps), continuous (none of those specified in the panel labeling of that vintage, were). IT whatever value breaker is installed in that position (presently the 50A 2-pole common trip 120/240 breaker second down from the top left) IS likewise THE limitation for the lower sub-bus ONLY, regardless. The lighting main is not subject to the other more limiting "Stab" limitation of this panel (70A), however IT and the use of numbered positions 1 & 2 (mains top left and right) are subject to a combined limit total of 125A (mains lug "maximum" and overall panel "maximum" limitation )

    No other position in the panel may

    The sub-bus (containing all those 15 & 20 A 120V poles) are all stabbed to the sub-bus which is singularly line side protected by the single 50A SUB-main circuit breaker. Those 120V 15 & 20A circuit breakers have nothing to do with the "Service" amperage current limitation "answer" to the OP's question(s).

    The three sets of circuit breaker poles I mentioned are the MAIN DISCONNECTS (plural) for the load-side of the supplying conductors' energy from the MAINS BUS(es) supplied via the MAINS LUGS of this panel.

    The OP has indicated a desire to ADD (not replace) a (2-P - Single-Phase) FEEDER circuit for Central Air Conditioning of unknown capacity. The source for same may not be from the sub-bus for this panel.

    The OP's panel includes 15 & 20 amp circuits which employ solid aluminum wiring, some of which has undersized neutrals, and some of which has a grounding conductor, solid aluminum of which are under-sized. Several (3 I counted) of the neutral conductors (grounded conductors) have been "attached" incorrectly to the N bus (under screw heads not inserted through terminals).

    The present current limiting devices installed upon the MAINS equal 130A (pair of tied 50A poles plus 30A 2-pole common trip plus the 50A common trip supplying the sub-main bus (containing 15 & 20 A single pole breakers). That equates to being "over-amped" at 5 A beyond the rated max for the mainS lugs and the MAINS Bus which was rated and required to be current limited to no MORE THAN 125 A.

    Unless the supplying conductors to this panel are line-side limited with a single device at 125A or less, the panel IS INDEED (again in the OP's language) "Over-amped".

    Whether or not there exists companion service equipment (another service panel in addition) is UNKNOWN. Whether or not THIS equipment is actually "the" (solitary) "service equipment" vs. "feeder" equipment is likewise unknown.

    As far as your assertion that the panel "looks untouched since its original instal" There are obvious indications that the opposite is true.
    Im well aware how these panels are put together and the loading factors through out. Whether we call all of the primary breakers mains or the sub breaker the main is irrelevant. The panel is based on the old 6 throw rule, 2 bus section design. Your post kind of contains unnecessary info to describe something simple. rms, 2poles ect, Its obvious, I get this.


    Im also not sure what you mean the aluminum is undersized, its hard to tell though from the pic. #12 is good for 15 amps #10 for 20amps, but its hard to tell if a breaker is to big for a branch circuit from the photos. You may be right about the terminations, but again this hard to tell.


    As for the main section being "over amped" it sounds like you are just counting the breaker ratings in the top section. 50+50+30+130. That is not how electricians do it. Its done via load calc. Load calc will prove that all 3 breakers together will never pull over 125 amps on the buss or what ever amps if the incoming feeds are rated less than 125. Technically yes the 80% continues rule applies, but I think its clear. I doubt this is a sub in that its a split buss, but hey you never know.

    If you believe the 6 throw rule is based solely one the handle ratings and not load calcs then show me the code article that is applicable.


  11. #11
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    It is not a "70 amp panel". You are correct. The home inspector was reading the wrong part of the label. He was correct to tell you the panel should be replaced.

    The AC guy recommended replacing that antique unit. He was correct. And his pricing was in the ballpark, IMO.

    The service entry conductors appear to be sized for about 100 amps max, so you may not have sufficient service there for what you are planning to add.

    An electrician should be hired to inspect all your Aluminum branch circuit connections. Then you can ask him to advise you about the panel and your plan to install AC.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  12. #12
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Mbrooke View Post
    Im well aware how these panels are put together and the loading factors through out. Whether we call all of the primary breakers mains or the sub breaker the main is irrelevant. The panel is based on the old 6 throw rule, 2 bus section design. Your post kind of contains unnecessary info to describe something simple. rms, 2poles ect, Its obvious, I get this.


    Im also not sure what you mean the aluminum is undersized, its hard to tell though from the pic. #12 is good for 15 amps #10 for 20amps, but its hard to tell if a breaker is to big for a branch circuit from the photos. You may be right about the terminations, but again this hard to tell.


    As for the main section being "over amped" it sounds like you are just counting the breaker ratings in the top section. 50+50+30+130. That is not how electricians do it. Its done via load calc. Load calc will prove that all 3 breakers together will never pull over 125 amps on the buss or what ever amps if the incoming feeds are rated less than 125. Technically yes the 80% continues rule applies, but I think its clear. I doubt this is a sub in that its a split buss, but hey you never know.

    If you believe the 6 throw rule is based solely one the handle ratings and not load calcs then show me the code article that is applicable.
    Hey fella, I don't know what to tell you, except you are wrong, and you speak volumes for the mis-application, incorrect modification, replacement, maintenance, moving circuits, etc. work done by two subsequent generations of ignorant DIYers and electricians.

    This panel may not have CBs rated above 70 amps in 1 or 2; the CB installed as the main sub bus protection may not exceed 100 A; and the combined simple math addition of the total of the amperage rating for position 1, 2 and the sub bus mains may not exceed 125 A and must be current limited to 125A max. Those are independant limitations for the panel. Rules that always must be met. IF the OP's title is correct and the information he provided is remotely correct (i.e. service equipment, not protected line side of same to 125 or less amps, then the panel limitations have been exceeded by the installation therein.

    The load calculations as you describe them have nothing to do with the limitations of this panel and its (the panel's) ratings/listings and the correct employment of it.

    I doubt that the supply to THIS panel actually even is/ARE actually truely "service entrance conductors" but a "main power feeder" be it 3 wire with or without ground.

    As far as your not being able to see or read the diagram nor the entirety of what the OP has pictured regarding the label and the interior of the panel, I can only say educate yourself, and use your "scroll bars".

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  13. #13
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    HG please stop tweaking the Forum to drop the Blue go to last Post Feature on your Thread reply's.





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  14. #14
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by H.G. Watson, Sr. View Post
    Hey fella,
    This panel may not have CBs rated above 70 amps in 1 or 2; the CB installed as the main sub bus protection may not exceed 100 A; <<Correct. and the combined simple math addition of the total of the amperage rating for position 1, 2 and the sub bus mains may not exceed 125 A and must be current limited to 125A max <<Only actual load current is limited to 125 amps. Handle ratings could combine up to 70+70+100=240amps. Those are independant limitations for the panel. Rules that always must be met. IF the OP's title is correct and the information he provided is remotely correct (i.e. service equipment, not protected line side of same to 125 or less amps, then the panel limitations have been exceeded by the installation therein.

    The load calculations as you describe them have nothing to do with the limitations of this panel and its (the panel's) ratings/listings and the correct employment of it.
    Show me the NEC code article that dictates this. Then I will say you are correct.


    If you went to any electrician or AHJ and said the service is not to code because the main disconnects add up to more than the buss rating or incoming feeders first thing he would ask for is 'what code section is being violated or not being met.'

    What prevents the top section from being overloaded are not the breaker handle ratings but the total calculated load. It is up to the job of the installing electrician to to a whole home load calc before installing or adding to that service as with any service. If the total calculated load comes out say at 13,440 VA which is 56 amps than you would go with #2 AL or #4 CU service conductors and a 100 amp panel. At this point your all set regardless if it was a main or split buss panel, regardless of what your 6 throws add up to handle wise. If you were to add load to the service, same thing, you do a load calc. If its still within value (ie, from 56amps it goes to 68amps) you can add that load without issue. If it goes above 80amps continues than you may not add load.

    I could have a 200 amp rated incoming service and split buss panel, 6 mains type. I could put in a 100amp for the lower lighting section, a 50 amp for the range, a 70amp for a second floor subpanel, a 30amp for the dryer, 20 amp the AC, and a 50 for a small detached garage subpanel. Water heater and heat are gas. The 6 mains would add up to 320 amps. However if the total load calc were to come out as say 116 amps max; that being the total sum of all the loads on all 6 mains put together, then you are ok. The NEC load calc would guarantee load a load diversity and presence that would not exceed the buss and service rating of 200amps or in this example the load will not go above 116 amps.

    Now, if I started adding monster load to the sub lighting section, upstairs sub panel, garage ect and the demand factor began exceeding 180 amps continues then I would have a code violation.

    Heck, In theory back than you could have a 200amp split buss panel with all the top section breakers being 125amps, 5 of them feeding into sub-panels around the house, adding up to 750amps total. Yet as long as those 5 subs and the lighting section as whole didn't load the service past its rating it was code complaint.

    Could one of these panels be overloaded without any breakers tripping? You bet! Could the service be loaded to the point of failing? Of course! One of several reason why they are no longer made, but back then the code making panel reasoned that whom ever installs or adds load to a split buss panel would first do a load calc. Of course that would be in a perfect world. Real world you have people loading the top section with 120amp tank-less water heaters, cheating the 6 throw rule (saw one panel where someone added 12 tandems in the top section giving 24 120volt circuits) and adding 50 amp welders, electric heat and the like to a 60 amp sub section. Of course that is when code is not followed.

    I could be wrong so far, but a code section can disprove my claims.


  15. #15
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Mbrooke
    burried comment inserted into quote of my post:

    <<Only actual load current is limited to 125 amps. Handle ratings could combine up to 70+70+100=240amps
    No it is not. It is "trying" to be limited to 130A in the OPs set up, however it is improperly applied and is not correct.

    However, strictly based upon what has been attempted - it is still not. The mere presence of the devices at the ratings stated (clamped, tapped, stabbed, whatever) is improper and a violation of the panel's labeled instructions, and therefore simply put a 110.3(b) violation.

    Not allowed. The Bus and the entire panel has a stated inserted limitation. You fail to realize how these were calculated (not tested). It is likewise why the overall is limited, the submain is limited and the two branch 120/240 positions (1 & 2) are limited ratings. It has to do with when any downstream is opened one side prior to the 120/240 breakers activating to open. But that is over your head and beyond your knowledge or experience, and beyond your '2011 code book'. As your understanding of a split bus panel, let alone a non-CTL. There is no 'rounding' allowed. There is no "load calculation" allowed that is all done prior to the selection of the breakers to be installed upon the mains. The mains limitations are absolute.

    Quote Originally Posted by Mbrooke View Post
    Show me the NEC code article that dictates this. Then I will say you are correct.


    If you went to any electrician or AHJ and said the service is not to code because the main disconnects add up to more than the buss rating or incoming feeders first thing he would ask for is 'what code section is being violated or not being met.'

    What prevents the top section from being overloaded are not the breaker handle ratings but the total calculated load. It is up to the job of the installing electrician to to a whole home load calc before installing or adding to that service as with any service. If the total calculated load comes out say at 13,440 VA which is 56 amps than you would go with #2 AL or #4 CU service conductors and a 100 amp panel. At this point your all set regardless if it was a main or split buss panel, regardless of what your 6 throws add up to handle wise. If you were to add load to the service, same thing, you do a load calc. If its still within value (ie, from 56amps it goes to 68amps) you can add that load without issue. If it goes above 80amps continues than you may not add load.

    I could have a 200 amp rated incoming service and split buss panel, 6 mains type. I could put in a 100amp for the lower lighting section, a 50 amp for the range, a 70amp for a second floor subpanel, a 30amp for the dryer, 20 amp the AC, and a 50 for a small detached garage subpanel. Water heater and heat are gas. The 6 mains would add up to 320 amps. However if the total load calc were to come out as say 116 amps max; that being the total sum of all the loads on all 6 mains put together, then you are ok. The NEC load calc would guarantee load a load diversity and presence that would not exceed the buss and service rating of 200amps or in this example the load will not go above 116 amps.

    Now, if I started adding monster load to the sub lighting section, upstairs sub panel, garage ect and the demand factor began exceeding 180 amps continues then I would have a code violation.

    Heck, In theory back than you could have a 200amp split buss panel with all the top section breakers being 125amps, 5 of them feeding into sub-panels around the house, adding up to 750amps total. Yet as long as those 5 subs and the lighting section as whole didn't load the service past its rating it was code complaint.

    Could one of these panels be overloaded without any breakers tripping? You bet! Could the service be loaded to the point of failing? Of course! One of several reason why they are no longer made, but back then the code making panel reasoned that whom ever installs or adds load to a split buss panel would first do a load calc. Of course that would be in a perfect world. Real world you have people loading the top section with 120amp tank-less water heaters, cheating the 6 throw rule (saw one panel where someone added 12 tandems in the top section giving 24 120volt circuits) and adding 50 amp welders, electric heat and the like to a 60 amp sub section. Of course that is when code is not followed.

    I could be wrong so far, but a code section can disprove my claims.
    110.3(b).

    Article 110-3(b) of the NEC states that Listed or labeled equipment shall be used or installed in accordance with any instructions included in the listing or labeling. Just because a breaker fits in the panel somewhere does not mean that it is okay to install it ANYWHERE in that panel or that you can ignore the stated limitations regarding placement, or combination restrictions labeled in the panel.



    BTW, Nothing in the "Code" between the years of the Manufacturing date and today permits you to employ or configure equipment in conflict with the original Listing, Labeling, (part of the listing) Instructions, the Standard(s) edition under which the original equipment was originally listed, nor the edition of the NEC to which it was listed under.


    (1) Suitability for installation and use in accordance with the NEC
    Note: Suitability of equipment use may be identified by a description marked on or provided with a product to identify the suitability of the product for a specific purpose, environment, or application. Special conditions of use or other limitations may be marked on the equipment, in the product instructions, or appropriate listing and labeling information. Suitability of equipment may be evidenced by listing or labeling.
    (2) Mechanical strength and durability
    (3) Wire-bending and connection space
    (4) Electrical insulation
    (5) Heating effects under all conditions of use
    (6) Arcing effects
    (7) Classification by type, size, voltage, current capacity, and specific use
    (8) Other factors contributing to the practical safeguarding of persons using or in contact with the equipment
    (B) Installation and Use. Equipment must be installed and used in accordance with any instructions included in the listing or labeling requirements.



    See the definitions of "Labeling" and "Listing" in Article 100.

    Failure to follow product listing instructions, such as the torquing of terminals and the sizing of conductors, is a violation of this Code rule


    What you seem to be unfamiliar with is the inability to safely open under fault conditions when a series (downstream) breaker opens first and the induction that occurs.

    There are a host of reasons Class-CTL (circuit limiting) panels and breakers were established (approx 65) and split bus convertable panels were eliminated from the market place.


    How far back does your NEC "library" go? are you willing to actually read five entire chapters of an older edition? Are you willing to read two complete obsolete editions of UL Standards? I seriously doubt that since you fail to read less then 500 words on a product label.

    and cannot see the forest for the trees in either a diagram nor identify what has been installed and where in the load center photo.

    You fail to realize it little to do with the panel's ability to supply a load - and nothing to do with load calculations. It has to do with the ability to function properly and protect (safely open) under EVENT CONDITIONS and not CATASTROPHICALLY FAIL in that regard.

    If you have a "stab" (oky in this cse footed or clamped) limitation that is absolute - it has nothing to do with the intended load or use on the branch or feeder. Same for mains lugs.

    If the OP had not blocked the entirety of the serial number for the panel (exposed just the aging portion) I could be exactly and precisely specific, IF I CARED TO DO SO for YOU.

    So what are you? an apprentice, a student, a weekend warrior?


    Last edited by H.G. Watson, Sr.; 09-14-2013 at 11:34 AM. Reason: Quoted his sneaky comment burried in his quote box of my post in his reply

  16. #16
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by H.G. Watson, Sr. View Post
    110.3(b).

    Article 110-3(b) of the NEC states that Listed or labeled equipment shall be used or installed in accordance with any instructions included in the listing or labeling. Just because a breaker fits in the panel does not mean that it is okay to install it ANYWHERE in that panel.



    From the label this is what I gather:

    Positions 1-14 can not be holding a breaker above 70 amps. That rule applies to both lower and upper sections from from my interpretation of "branch".

    The breaker that feeds the sub section (lower section) can not be over 100amps.

    Equipment is suitable as a main panel as long as the top section does not exceed 6 breakers. Double poles count as 1 since its handles are tied.

    Panel shall not have more than 22 poles in it.

    Service lugs can take 6 to 2/0 wire aluminum or copper.

    Main ratings 120/240 AC 125 amps (note not mainS rating). What that means is that under any operating condition the power flowing into the panel through the main lugs shall not exceed that. In this case it shall not exceed 125 amps. 125amps what the buss and lugs were sized for. No where does it say that the 6 disconnects cant add up beyond 125 amps. Only limit is that a branch breaker cant be above 70 amps.

    If for what ever reason GE didn't want the handle ratings of the upper sections adding up above 125amps, then we would have something along the lines of this on the label: "The total combined sum of all service disconnect intended breakers' ampacity as marked on switching toggle shall not exceed 125 amps"

    Nowhere does it say this. One could have 2 70amp and 1 100amp sub breaker (70+70+100=240amps) in the upper section without any listings being violated. Its not explicitly written or indicated. If we found an 80 or 90amp breaker anywhere other than where the sub main then we would be violating a listing that is clearly there.

    Going back to the statement: "50 + 30 + 50 = 130 which exceeds mains max 125A, that's your panel only ? so the "panel over amped" yeah." Nothing in the labeling supports that.

    Only other thing that could dictate a violation is an NEC article indicating the they cant add up over what the buss bar is rated. But no where can I find this.

    From what I gather I think you believe that all split buss panels cant have the mains add up more than the buss but that is not the case.

    Just borrowing this from another thread. Sorryon my part:



    Top left diagram indicates either service conductors or a buss rated at 150amps. Most likely the buss is 200 or 225 amps rated but the conductors are the limiting factor here at 150. Mains add up to 270 amps. (30+30+30+30+50+100=270). As long as nothing in the labeling says otherwise (rarely does it) its ok to do. It would appear the panel is "over amped", but again it not, what stops that is a load calc by the electrician that proves that those 6 breakers will never pull a combined current of over 150amps on the service wires.


  17. #17
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    This is what happens when people rely on non-conditional editorial summaries in "handbooks" without knowledge of the code itself or what, where, and why phrasing is sourced from and how to apply it.

    The examples given for the upper right diagram and lower left diagram are qualified to the panel labeling and listing AND both require remote protection i.e. current limitation remotely.

    The discussion as qualifed to be used as service equipment is a panelboard requirement for the OCCUPANCY control for a single dwelling unit.

    The examples given are for when employed using an exception regarding the MAIN POWER FEEDER to the occupancy not requiring a four-wire configuration for the FEEDER from the remote protection, and allowing Grounding/Neutral bonding at the occupancy panel, which was allowed and is still allowed for DWELLING UNITS.

    The allowance/exception still requires the entirety for the occupancy to be carried in its entirety by the feeder, but it is not a true "service" as the hots are current limited at the REMOTE (beginning) of the main power feeder, they are just not with an isolated ground.

    3-W no ground (grounding doesn't have to be a wire or cable btw) feeders are still commonplace and in the vintage of this panel were the NORM.

    Hint, even a four-wire (H-H-N-G) feeder to an accessory structure requires (other than a single branch circuit MWBC 30A or less) requires a "service disconnect" for the structure - but its "not a service" as employed.

    Try actually reading all the ALL of the related articles of even your present edition. Then try reading the applicable sections (they won't be numbered or configured the same, and some will be in completely different (higher numbered) chapters of an NEC edition more relevant to the time period THIS equipment was manufactured. Then grab yourself a vintage white book and have a read - heck you can find a significant portion referenced as to 2005, but you'd still need to go back significantly further to UNDERSTAND the history of the changes in the equipment standards (both panelboards and miniture circuit breakers).


  18. #18
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by H.G. Watson, Sr. View Post
    This is what happens when people rely on non-conditional editorial summaries in "handbooks" without knowledge of the code itself or what, where, and why phrasing is sourced from and how to apply it.

    The examples given for the upper right diagram and lower left diagram are qualified to the panel labeling and listing AND both require remote protection i.e. current limitation remotely.

    The discussion as qualifed to be used as service equipment is a panelboard requirement for the OCCUPANCY control for a single dwelling unit. Code section please

    The examples given are for when employed using an exception regarding the MAIN POWER FEEDER to the occupancy not requiring a four-wire configuration for the FEEDER from the remote protection, and allowing Grounding/Neutral bonding at the occupancy panel, which was allowed and is still allowed for DWELLING UNITS.

    The allowance/exception still requires the entirety for the occupancy to be carried in its entirety by the feeder, but it is not a true "service" as the hots are current limited at the REMOTE (beginning) of the main power feeder, they are just not with an isolated ground.

    3-W no ground (grounding doesn't have to be a wire or cable btw) (I know, conduit can be the EGC when the customer doesnt want to spend mullah) feeders are still commonplace and in the vintage of this panel were the NORM.

    Hint, even a four-wire (H-H-N-G) feeder to an accessory structure requires (other than a single branch circuit MWBC 30A or less) requires a "service disconnect" for the structure - but its "not a service" as employed.

    Try actually reading all the ALL of the related articles of even your present edition. Then try reading the applicable sections (they won't be numbered or configured the same, and some will be in completely different (higher numbered) chapters of an NEC edition more relevant to the time period THIS equipment was manufactured. Then grab yourself a vintage white book and have a read - heck you can find a significant portion referenced as to 2005, but you'd still need to go back significantly further to UNDERSTAND the history of the changes in the equipment standards (both panelboards and miniture circuit breakers).

    I fail to see how a handbook can include something that is wrong that is under the guidance of the vary code making panel it supports. The very text it references.

    Show me the code section that requires those 2 panels to have remote current limitation/ protection. If they did than we wouldn't be seeing the 6 throw rule applied to them. And a main kill doesn't need to be in a house, it can be outside only.

    "examples given are for when employed using an exception regarding the MAIN POWER FEEDER to the occupancy not requiring a four-wire configuration for the FEEDER from the remote protection, and allowing Grounding/Neutral bonding at the occupancy panel, which was allowed and is still allowed for DWELLING UNITS"

    No way. Show me the code article. Any time you have a main service/remote over current device the grounding and grounded conductors become separated from that point on. (SER after the SEU) Those panels would be sub panels not main panels.

    So far nothing has been presented that show that the above over amp is a violation. My Uncle and Father in the 60s, 70s and early 80s before they retired installed 10s of thousand of residential panels in cookie cutter sub divisions half of which were split buss types and most had the 6 throws add up more than the the rating. AHJ inspector approved it and the houses are still standing fine.


  19. #19
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    One of the most common arrangements of these panels is a factory installed 50 AMP breaker for the lighting section, and a 50 AMP breaker for a range, a 30 AMP breaker for a dryer, and possible another 30-50 AMP breaker for an A/C in the "main" section.

    Plain English explanations, diagrams, and facts never seem to deter Watson from disagreeing with practically everything anyone else presents.

    National Electrical Code Handbook 2011 - highlights are mine

    230.80 Combined Rating of Disconnects

    Where the service disconnecting means consists of more than one switch or circuit breaker, as permitted by 230.71, the combined ratings of all the switches or circuit breakers used shall not be less than the rating required by 230.79.

    Section 230.71(A) permits up to six individual switches or circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or several
    switchboards, to serve as the required service disconnecting means at any one location.

    Section 230.80 refers to situations in which more than one switch or circuit breaker is used as the disconnecting means and indicates that the combined rating of all the switches or circuit breakers used cannot be less than the rating required for a single switch or
    circuit breaker.

    Section 230.90 requires an overcurrent device to provide overload protection in each ungrounded service conductor.

    A single overcurrent device must have a rating or setting that is not higher than the allowable ampacity of the service conductors. However, Exception No. 3 to 230.90(A)
    allows not more than six circuit breakers or six sets of fuses to be considered the overcurrent device. None of these
    individual overcurrent devices can have a rating or setting higher than the ampacity of the service conductors. In complying with these rules, it is possible for the total of the six overcurrent devices to be greater than the rating of the service-entrance conductors.However, the size of the service-entrance conductors is required to be adequate for the computed load only, and each individual service disconnecting means is required to be large enough for the individual load it supplies.


    Occam's eraser: The philosophical principle that even the simplest solution is bound to have something wrong with it.

  20. #20
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    110.3(b) The original listing & labeling.

    Quoting a standard (the NEC) editions, even decades later is irrelevant.

    Quoting a Handbook is irrelevant.

    Notice selective quoting which has nothing to do with the Panelboard requirements. Priceless.


  21. #21
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Come on Robert, you know the book is wrong when it does not support your position.

    All answers based on unamended National Electrical codes.

  22. #22
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Jim Port View Post
    Come on Robert, you know the book is wrong when it does not support your position.
    The commentary contained in the Handbook is not the official interruption. One would have to submit in writing a request for an official interruption of the NEC to the NFPA. All though the authors of the commentary are viewed a experts in the NEC, there are instances where the commentary is based on an obscure and unofficial viewpoint. And certainly the comments would not be enforceable as a code requirement without an official interruption.

    I view the explanatory material in the NEC Handbook only as "fairly good training material for those that don't have any experience".

    "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

  23. #23
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    So, whatever happened to dead Jim?

    Department of Redundancy Department
    http://www.FullCircleInspect.com/

  24. #24
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Old Jimmy stirred the pot and now laughing in his grave.


  25. #25
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Jeff Langhorn View Post
    Old Jimmy stirred the pot and now laughing in his grave.
    Shame on ya.

    As the desperate grabs from a NECH code cycles long after the panel in question was manufactured, Laughable.

    Grabbing a portion which clearly states protection ahead such as a main occupancy feeder - not a service.

    Funny how no one else actually LOOKS at the pictures and references the actual cable feed. Ignorant!

    The phasing of the code and the listing required overload not merely overcurrent protection.

    The panel has been altered since its original installation. It is photographed IN CONFLICT with its labeling and in CONFLICT with its Listing. Can't even be bothered to read the actual pertaining NEC edition, likely as they don't know where in the older editions to FIND the information.

    The OP is long gone and likely flooded, including his frontage disco and light post feed prior to the feeder to the meter.


  26. #26
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Mbrooke View Post
    That means nothing. I can count the breakers in any panel and 90% of the time it exceeds the main feeder or the buss rating sometimes by 5 fold. Local commercial building near by has a 6 throw main, utility feed and switch gear buss bars are rated 2000amps max, total breaker counts hover around 3000amps. It was done all the time and still is in commercial/industrial.

    I dont believe that service is an issue. It looks untouched from the original install. If those main conductors are #2 which is my bet than its a 100 amp service. Smaller or larger will dictate if its less than 100amps or up to the max of 125. If the major loads are limited, ie only the dryer and oven are electric and house is 1500sq feet; then a 2.5 ton AC and an AHU should not be a problem. If the house is all gas AC could be 6 tons easy. But the final factor to determine an over amp would be a load calc, which I don't think would be exceeded here.

    I would however be way more concerned about the single stranded aluminum wires.
    Mbrooke is right.


  27. #27
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    Question Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Jimmy Hoffa View Post
    I know nothing about this stuff having just bought my first house after renting all my life. My inspector told me I had a 70 amp panel which was about overamped as it was and needed to be replaced soon after moving in, especially before installing AC.



    So in short, can anybody tell me what my service is based on some pictures I've taken?








    First - Let me say that I am relieved to hear that you are alive and well Jimmy After all it has been a long time since you disappeared from 7 mile rd in Detroit

    OK - Let's get down to the real issue hear - Total Service vs Total service allowed.

    I do agree it is unclear as to what the manufacture intended however there is on clue that should help - Maximum wire size 2/0 which will give us a good idea of what the bus can handle.

    I grabbed a couple of quick references off the web just to take a quick look

    American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies and wire strength
    2 0.2576 6.54304 0.1563 0.512664 181Maximum amps for chassis wiring 94Maximum amps for
    power transmission
    Electrical Wire Sizes - What Size Electrical Wire Do I Need
    Service Panels, Sub Panels 100 Amps 2 Gauge

    Electrical Wire Sizes
    Conductor
    Size (AWG)
    Maximum Amperage Diameter (in) Resis-
    tance
    ohm/
    1000'*
    NEC prem-
    ises
    NEC General ARRL2 TFE insulated3 Chassis wiring1 Power Trans-
    mission1
    stranded Solid
    Bun-
    dled 140F insl.
    Single 194F insl. Bun-
    dled
    Single Bun-
    dled
    Single
    0000 4/0 195 405 380 302 0.46 0.05
    00 2/0 200 145 300 87 169 283 190 0.36 0.08
    0 110 220 75 147 245 150 0.38 0.32 0.1
    1 150 95 190 211 119 0.33 0.29 0.13
    2 85 165 50 108 181 94 0.3 0.26 0.16
    4 100 70 140 40 81 135 60 0.24 0.2 0.25
    6 50 55 105 30 60 101 37 0.19 0.16 0.4
    8 40 40 80 23 44 73 24 0.15 0.13 0.64
    10 30 30 55 16 33 55 15 0.12 0.1 1.02
    12 20 25 40 23 41 12 25 41 9.3 0.09 0.08 1.62
    14 15 20 35 17 32 8 19 32 5.9 0.07 0.06 2.58
    16 - 24 13 22 6 13 22 3.7 0.06 0.05 4.08
    18 - 18 10 16 5 9.2 16 2.3 0.05 0.04 6.52
    20 7.5 11 3.7 6.5 11 1.5 0.04 0.03 10.36
    22 5 7 2.5 4.5 7 0.92 0.03 16.46
    24 2 3.3 3.5 0.58 0.02 25.67
    30 0.7 1.3 0.86 0.14 0.01 103.2
    AWG - American Wire Gauge
    National Electrical Code [NEC Article 240.3]
    Also National Fire Protection Association (NFPA 70)
    - Cable sizing for premises wiring.
    Wire must be two sizes larger (lower AWG) for Aluminum Wire.
    NEC Article 310 Conductors for General Wiring. (2008 Edition)
    There two tables in this article one for bundled conductors and one for free air conductors. Each has three voltage ranges for insulation with different melting temperatures.
    We used the low (60C insulation bundled) and high (90C insulation free air) values.
    - Table 310.17 - Allowable Ampacities of Single-Insulated Conductors Rated 0 Through 2000 Volts in Free Air, Based on Ambient Air Temperature of 30C (86F)
    - Table 310.16 - Bundled cables
    Insulation temperature ratings:


    • 60C (140F): Types TW, UF
    • 75C (167F): Types RHW, THHW, THW, THWN, XHHW, ZW
    • 90C (194F): Types TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, ZW-2




    So as one can see from the sources quoted above (sorry didn't find NEC table right away) we are looking at real limits in the area of 100-150 amp service with out getting into insulation types or wire type (note that it specified Al or Cu wire - which have different ratings as well)

    So Jimmy how was your last meal at the Weather vain ?

    BTW - Replace the entire service and upgrade to 200 amps , if your talking about a big AC unit it will be worth it especially with todays electronics being so sensitive to power dips that can be caused by drawing full or near load capacity of circuits , wires, transformers they all have weak links that can cause problems

    FYI - your home inspector did a poor job on identifying the electrical circuit (if this is what he really told you) and I might be suspicious about other parts of his inspection as well.


  28. #28
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Dwight Doane View Post
    First - Let me say that I am relieved to hear that you are alive and well Jimmy After all it has been a long time since you disappeared from 7 mile rd in Detroit

    OK - Let's get down to the real issue hear - Total Service vs Total service allowed.

    I do agree it is unclear as to what the manufacture intended however there is on clue that should help - Maximum wire size 2/0 which will give us a good idea of what the bus can handle.

    I grabbed a couple of quick references off the web just to take a quick look

    American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies and wire strength
    2 0.2576 6.54304 0.1563 0.512664 181Maximum amps for chassis wiring 94Maximum amps for
    power transmission
    Electrical Wire Sizes - What Size Electrical Wire Do I Need
    Service Panels, Sub Panels 100 Amps 2 Gauge

    Electrical Wire Sizes
    Conductor
    Size (AWG)
    Maximum Amperage Diameter (in) Resis-
    tance
    ohm/
    1000'*
    NEC prem-
    ises
    NEC General ARRL2 TFE insulated3 Chassis wiring1 Power Trans-
    mission1
    stranded Solid
    Bun-
    dled 140F insl.
    Single 194F insl. Bun-
    dled
    Single Bun-
    dled
    Single
    0000 4/0 195 405 380 302 0.46 0.05
    00 2/0 200 145 300 87 169 283 190 0.36 0.08
    0 110 220 75 147 245 150 0.38 0.32 0.1
    1 150 95 190 211 119 0.33 0.29 0.13
    2 85 165 50 108 181 94 0.3 0.26 0.16
    4 100 70 140 40 81 135 60 0.24 0.2 0.25
    6 50 55 105 30 60 101 37 0.19 0.16 0.4
    8 40 40 80 23 44 73 24 0.15 0.13 0.64
    10 30 30 55 16 33 55 15 0.12 0.1 1.02
    12 20 25 40 23 41 12 25 41 9.3 0.09 0.08 1.62
    14 15 20 35 17 32 8 19 32 5.9 0.07 0.06 2.58
    16 - 24 13 22 6 13 22 3.7 0.06 0.05 4.08
    18 - 18 10 16 5 9.2 16 2.3 0.05 0.04 6.52
    20 7.5 11 3.7 6.5 11 1.5 0.04 0.03 10.36
    22 5 7 2.5 4.5 7 0.92 0.03 16.46
    24 2 3.3 3.5 0.58 0.02 25.67
    30 0.7 1.3 0.86 0.14 0.01 103.2
    AWG - American Wire Gauge
    National Electrical Code [NEC Article 240.3]
    Also National Fire Protection Association (NFPA 70)
    - Cable sizing for premises wiring.
    Wire must be two sizes larger (lower AWG) for Aluminum Wire.
    NEC Article 310 Conductors for General Wiring. (2008 Edition)
    There two tables in this article one for bundled conductors and one for free air conductors. Each has three voltage ranges for insulation with different melting temperatures.
    We used the low (60C insulation bundled) and high (90C insulation free air) values.
    - Table 310.17 - Allowable Ampacities of Single-Insulated Conductors Rated 0 Through 2000 Volts in Free Air, Based on Ambient Air Temperature of 30C (86F)
    - Table 310.16 - Bundled cables
    Insulation temperature ratings:


    • 60C (140F): Types TW, UF
    • 75C (167F): Types RHW, THHW, THW, THWN, XHHW, ZW
    • 90C (194F): Types TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, ZW-2


    So as one can see from the sources quoted above (sorry didn't find NEC table right away) we are looking at real limits in the area of 100-150 amp service with out getting into insulation types or wire type (note that it specified Al or Cu wire - which have different ratings as well)

    So Jimmy how was your last meal at the Weather vain ?

    BTW - Replace the entire service and upgrade to 200 amps , if your talking about a big AC unit it will be worth it especially with todays electronics being so sensitive to power dips that can be caused by drawing full or near load capacity of circuits , wires, transformers they all have weak links that can cause problems

    FYI - your home inspector did a poor job on identifying the electrical circuit (if this is what he really told you) and I might be suspicious about other parts of his inspection as well.
    Thank you for the tables! From my take on the label, my belief is the panel is limited to 125amps as said below "main ratings". Of course the incoming service gauge a limiting factor as well too. The 6 to 2/0 is what the top lugs can handle without issue. One may see larger wire than the given current such as an application in a distant out building where voltage drop is an issue or simply no smaller wire was available at the time of install.

    Its obvious the panel label was not to well thought out on GEs part, it should be more specific on the goal its are trying to accomplish. The 22 poles part can be confusing as well when the panel is in a main application in that you only use 14 single pole spaces. The 22 count goes for sub panel applications, ironically that the last place a split buss panel would be, but the top section does allow THQP thin style GE breakers which would mean 8 could be put in the top section and 14 in the bottom giving 22 poles maximum.

    As for what determines service conducter size in residential service application after the load calc is done is NEC table 310.15 (B) (7). Of course one could also use the standard tables but this is the norm for most electricians:

    (7) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services
    and Feeders. For individual dwelling units of onefamily,
    two-family, and multifamily dwellings, conductors,
    as listed in Table 310.15(B)(7), shall be permitted as
    120/240-volt, 3-wire, single-phase service-entrance conductors,
    service-lateral conductors, and feeder conductors
    that serve as the main power feeder to each dwelling unit
    and are installed in raceway or cable with or without an
    equipment grounding conductor. For application of this section,
    the main power feeder shall be the feeder between the
    main disconnect and the panelboard that supplies, either by
    branch circuits or by feeders, or both, all loads that are part
    or associated with the dwelling unit. The feeder conductors
    to a dwelling unit shall not be required to have an allowable
    ampacity rating greater than their service-entrance conductors.
    The grounded conductor shall be permitted to be
    smaller than the ungrounded conductors, provided the requirements
    of 215.2, 220.61, and 230.42 are met.

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  29. #29
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Dwight Doane View Post

    BTW - Replace the entire service and upgrade to 200 amps , if your talking about a big AC unit it will be worth it especially with todays electronics being so sensitive to power dips that can be caused by drawing full or near load capacity of circuits , wires, transformers they all have weak links that can cause problems

    FYI - your home inspector did a poor job on identifying the electrical circuit (if this is what he really told you) and I might be suspicious about other parts of his inspection as well.

    Sorry ran out of room on the last post, hence the 2nd post.

    Whether or not the service should be replaced is difficult to tell from the pictures. 200 amps is rarely needed on smaller and medium size homes even with AC. The only thing that will justify a 200amp service if loading requires it, ie all electric heat or large hottubs. Of course one can up-size for future needs if so, but its not required.

    A 200amp service may do little, if anything to improve power dips from motor inrush. The service conductors may be larger from the meter pan to the panel (also from the weather head to the meter pan in over head applications), but the poco feeders will be the same. They are usually by far the worst offenders, where there is not much the customer can do. Pocos will usually run long feeds from the transformers and size them as small as possible. Its also not uncommon for a single 25kva pole top transformer to run several residences, up to 10 if load is light enough. Over head circuits are usually the worst with voltage drop in that a very thin conductor can be used without danger. Even if it runs very hot, because its in air and on porcelain insulators there is no danger where there would be if in direct burial or conduit.


  30. #30
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    A 60C single pole breaker set or 60C wiring (TW-AL) or lower temperature rated lugs upon same limits the entire mains buss and its supply conductors (THW) to 60C and not 75C ratings. Weakest link, lowest temperature rating of the chain.Lighting & appliance sub-bus is series protected which is where those 60C (or less) breakers are allowed.Prior to 1981 the limitations were found in the Standards for safety for panelboards, circuit breakers, etc., hence the 110.3(b), i.e. listing and requirements thereof, reference. When language and limitations phrasing was amongts the CMPs regarding was incorporated into the NEC, both the ratings methods (testing vs. calculations), the requirements to be met, the labeling and listing limitations, and the standards had changed dramatically, and the concept of an entity other than UL regarding a testing and listing entity, had been realized.


  31. #31
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by Gunnar Alquist View Post
    You have a good point "jack davenport".
    Gunnar, you don't have to worry either!!!!


  32. #32

    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Quote Originally Posted by jack davenport View Post
    Do we really know if people here are using their real names, or one plucked from the phone book ??
    Okay, okay, you caught me. My real name is Phineas T Fuddrucker but since no one knows how to spell Phineas, I use Dana instead.

    True Professionals, Inc. Property Consultant
    877-466-8504

  33. #33
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    Default Re: Electric Panel Service Amps, Was my inspector wrong?

    Solid-strand (120 V) branch circuit aluminum wiring.

    Tom Rees / A Closer Look Home Inspection / Salt Lake City, Utah

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