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Thread: 100 Amp Panel Breaker Capacity

  1. #11
    Join Date
    May 2004
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    Midwest
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    766

    Re: 100 Amp Panel Breaker Capacity

    The problem is that I hardly ever see on the panel board how many tandems can go in, Where is the best spot to look
    Master Electrician

  2. #12
    Join Date
    Feb 2003
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    Florida
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    Re: 100 Amp Panel Breaker Capacity

    Originally posted by jes25:
    The problem is that I hardly ever see on the panel board how many tandems can go in, Where is the best spot to look
    Look at the slots on the panelboard busbars. A panelboard that allows tandems will have a different configuration at the locations the tandems are permited. A compliant tandem breaker will not fit into a slot not permited for tandems, however their are non-compliant breakers on the market that will fit in a non-tandem spot.

    Panelboard manufacturers are required to make class CTL current limiting panelboards to not exceed 42 devices, breaker manufacturerers are not.
    Bryan P. Holland, MCP

  3. #13
    Join Date
    May 2004
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    Midwest
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    766

    Re: 100 Amp Panel Breaker Capacity

    So basically if I have an ITE panel for example and an ITE tandem if it fits I should assume it is compliant and OK of course none over 42
    Master Electrician

  4. #14
    Join Date
    Mar 2003
    Location
    Michigan
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    129

    Re: 100 Amp Panel Breaker Capacity

    This might be the reason the inspector said 12 spaces for a 100 amp panel, possible the panel in questioned is 12 spaced and listed not to have more than 12 breakers single poles.

  5. #15
    a.wayne3@verizon.net Guest

    Re: 100 Amp Panel Breaker Capacity

    Look at a panel buss bars, homeline for example,They make a 40/40 and a 40/42 panel.
    The 40/42 has step buss bars and the 40/40 is squared off.Hense the tandems won`t fit unless you remove the metal tab on the tandem breaker
    and that would be a violation.

  6. #16
    Join Date
    Feb 2003
    Location
    New Jersey
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    2,424

    Re: 100 Amp Panel Breaker Capacity

    I just had an inspector tell me that the maximum number of breakers that a 100 amp panel can have is 12. Could this be remotely true?
    In general, most of the main breaker panels sold have configurations of 20 circuit/100 amp, 30 circuit/150 amp and 40 circuit/200 amp. (I believe the 100 amp panels are available in smaller configurations). If you are using panelboards (bolt-in breakers) they are available in up to 42 circuits.

    Sq D also makes a 200 amp main breaker, 30 slot - 40 circuit panel which they consider a "remodel" breaker panel. If you look at the buss bar, the bottom five breaker positions on each side are stepped (as awayne mentioned) making it acceptable to install tandem breakers in those positions and giving you the possibility for 40 s/p circuits. In addition, if you look at the breaker directory on the panel cover it displays the top 30 breaker positions with plain white rectangular slots in which to write in an identification. The bottom 10 slots have a dashed line through the center of the rectangular box for an "a" and "b" identification.

    In a recent kitchen remodel job I added a wall oven and 2 counter receptacle circuits. The homeowner had an older 100 amp Sq D QO panel with several tandem breakers already installed. There was enough room to install the breakers I needed to but when the inspector looked at the panel he red tagged it and required me to either prove that the panel was designed to accept tandem breakers or install a sub-panel (his tip-off was the directory on the panel door). I installed the sub-panel even though the original panel (mechanically) accepted the tandem breakers. So not all buss bars are stepped.

    the tandems won't fit unless you remove the metal tab on the tandem breaker
    Awayne, be careful what you post here. Not all of us on the list are licensed electricians whose livelihood depends on "doing things right" and "doing right things".

    Regards,

    Phil

    [ May 14, 2004, 06:22 AM: Message edited by: goldstar ]

  7. #17
    Join Date
    May 2004
    Posts
    1

    Re: 100 Amp Panel Breaker Capacity

    Just so you'll know Murray now makes a 100 amp 20-40 circuit load center. (LC2040MB1100) To get a copper buss add CU at the end of the cat #.

  8. #18
    Join Date
    Feb 2003
    Location
    Indiana
    Posts
    299

    Re: 100 Amp Panel Breaker Capacity

    ITE makes a main breaker 100A panel with 30 full size spaces. Square D makes a 32 circuit 100A main breaker panel. In my opinion, a 100A main breaker panel can have as many circuit capacity that it has been listed and labeled for by a NRTL.

  9. #19
    Join Date
    Feb 2003
    Location
    Florida
    Posts
    7,285

    Re: 100 Amp Panel Breaker Capacity

    Space and load capacity aren't always the same. One could install several smaller circuits and require more space, while another installs larger circuits needing less space. In either case the loads are the same.

    I've had a few custom builders that specified only two receptacle outlets per circuit in a couple of the rooms. This meant one room could have up to 4 branch circuits alone. However, as far as the service is concerned, the load applied wouldn't be any different had the 4 circuits only been one.
    Bryan P. Holland, MCP

  10. #20
    a.wayne3@verizon.net Guest

    Re: 100 Amp Panel Breaker Capacity

    Phil I also posted that would be a violation.D.I.Y are out there just go to the big orange and look in the electrical aisle,buying pipe wire and asking how do I install this to a pimpled faced kid that just got out of H.S.This is a site for electricians not homeowners.We have paid our dues and have learned from the trade not some book we bought at a home improvement store.We here still learn everyday we go to WORK
    at least I do,I don`t know it all but I know allot and am still learning as I go about my daily routine.That`s why we have jouneymen cards and masters licences.Not a deed to a home.

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