Circuit breaker question

Discussion in 'Electrical and Wiring' started by mmcvicker, Jan 10, 2008.

  1. Jan 10, 2008 #1

    mmcvicker

    mmcvicker

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    When i opened my box last night i noticed that some of the breakers have 2 black wires running to them while others only have 1. Are there 2 circuits running off of 1 breaker. These are Square D QO breakers and are also not tandems. The breakers do have a slot on each side of the screw for wire to be connected.

    If it is 2 circuits on 1 breaker would i be able to add a new circuit to an existing lightly used breaker?

    Thanks
     
  2. Jan 10, 2008 #2

    kok328

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    Yes, this is 2 circuits running off one breaker.
    Yes, as long as the other breaker has the same type of lug (slot on each side of the screw).
     
  3. Jan 11, 2008 #3

    glennjanie

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    Welcome M McVicker:
    The first wires doubled up on breakers were not legal (if my memory serves me correctly) and the new one won't be either. But then, that's why we use circut breakers; if you overload the breaker by using it on 2 circuts it will kick out.
    I love the Square D QO's; one saved my son-in-law's life when the GFCI in the circut didn't detect him standing in a puddle of water using a power saw.
    Glenn
     
  4. Jan 11, 2008 #4

    kok328

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    What you have and what you propose IS perfectly legal.
    Glennjanie, these particular breakers are designed for a two circuit setup.
    Of course you'll want to be prudent about overloading it.
     
  5. Jan 12, 2008 #5

    ToolGuy

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    for all practical purposes, the 2 circuits become 1. Really no different than branching out after the first gang box, except here it's branching out immediately from the breaker.
     
  6. Jan 12, 2008 #6

    guyod

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    If im Think of the right Square D they make a double breaker with 2 15 amps switches that fits in one slot. (each wire has its own switch and amps )Then you would have nothing to worry about. Like not having enough wire to move circuits to other breakers.
     
  7. Jan 15, 2008 #7

    speedy petey

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    This works ONLY IF your panel accepts this type of breaker. Not all do.

    If it's two VERY light loads, then pigtailing or (legally) doubling up is fine.
     
  8. Jan 15, 2008 #8

    mmcvicker

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    We have decided to upgrade the service to 200amp. It just seems like the right thing to do and will allow us for expansion in the future if needed. Thanks for all of the input.
     
  9. Jan 15, 2008 #9

    ToolGuy

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    That is a great decission, even increases your property value. :cool:
     
  10. Jan 15, 2008 #10

    guyod

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    Im sure no one will agree with me but upgrading to 200 is over kill for 95% of homes. I have electric heat, electric hot water heater, and every electric device you can think of. my electric bill get up to $500 in the winter. Only have 100 amps. Even if i did ever trip my 100 amp breaker. i still wouldnt want to upgrade because if i was using more than 100 amps at a time i would want my electric to turn off. It would be like my house giving me a slap in the back of the head telling me to use less electric.
     
  11. Jan 15, 2008 #11

    speedy petey

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    Well then I guess you've never done a load calc on a new home. Or you have never wired a new 1800+ sq/ft home ending up with a FULL 200 amp panel.

    Instead of installing a sub panel in a brand new house, I'd rather install a 40 space 200A panel.
     
  12. Jan 15, 2008 #12

    kok328

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    I'm seeing some correlation between amps and number of breakers here. If it's more breakers you need, go with the "space saver" breakers or a sub-panel. Guyod's opinion is valid (in my opinion), amp probe a 100amp service on an average size home and you'll find that 100 amps is plenty, unless your running some equipment not typical to an average home (i.e.- an air compressor, welder, etc...). Even then, unless your running this type of equipment constantly, 100 amps is plenty. Also, it's my understanding that if you upgrade to 200amps, you'll have to upgrade the incoming wires from the utility company (not a DIY situation).
     
  13. Jan 16, 2008 #13

    speedy petey

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    a) "Space saver", twin, skinny, whatever you want to call them, breakers, are NOT allowed in all panels. In the US a panel is limited to 42 circuits. Most residential 200A panels are limited to 40 "spaces". Most 100A are 20 or 24 space, with a 30/32 available but rare.
    I think a 100A service with a sub-panel is QUITE cheesy in a new or even slightly modern home.
    If a demand load comes in under 100 amps it will NOT be much under. WHY would you want to cut it that close with the way we are constantly expanding our demands of electrical systems????

    b) An Amprobe will tell you NOTHING with regard to a house's demand load. This is a meaningless measurement.

    c) The incoming OVERHEAD wires are NOT the customer's responsibility or concern. The POCO will change them as they see fit.
    Underground service laterals are different from place to place, with most places it being the customer's responsibility.
     
  14. Jan 16, 2008 #14

    guyod

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    With a new house its a no brainer you put a 200amp service in. The breakers do fill up fast and 10 years from now the owner will probably need a 100 amp breaker to plug his electric car in. My comment was toward existing breakers.
    Dont knock sub panels. I installed a elec. baseboard heater in the kitchen. The panel was 50 feet way and the house was 2 story slab. luckily there was a sub panel in the kitchen.
     
  15. Jan 16, 2008 #15

    speedy petey

    speedy petey

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    Oh, I'm not knocking sub-panels. They can be a wonderful thing and a huge help.
    I am knocking a mandatory sub-panel because we ran out of space, even due to a service change.
     
  16. Jan 16, 2008 #16

    ToolGuy

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    I say just run a heavy duty extension cord from the top of the pole and forget about the breaker panel altogether. But then there's all these "rules". :p
     
  17. Jan 16, 2008 #17

    guyod

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    I would if i could. it would save money for more projects and tools
     
  18. Jan 16, 2008 #18

    mmcvicker

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    i am really kicking myself for not doing a 200 amp service when the house was built 5 years ago. I was not really thinking i guess, they were kind enough to give me a 150 amp box :(

    Maybe i can try to get my neighbors to run a few heavy duty extension cords from their house into my basement :)
     
  19. Jan 16, 2008 #19

    ToolGuy

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    Now that's my kind of thinkin'! :p
     
  20. Jan 23, 2008 #20

    JoeD

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