Basic electric service panel questions

Discussion in 'Electrical Forum discussion & Blog' started by JMingrone, Jul 17, 2013.

  1. JMingrone

    JMingrone New Member

    Messages:
    49
    Location:
    Connecticut
    I'm having a home inspection this weekend on the house I'm selling and I'm a little concerned about the electrical inspection.

    A couple quick questions:
    1) For a 200 amp service, you draw 200 amps from each leg, right?
    2) Is it a problem (does code require) that the breakers on each leg total to less than 200? Or is it only necessary that the actual load being drawn be less than 200 amps? I have a total of 230 amps of breakers on one leg and 200 on the other.

    Will this be a problem?

    Thanks
  2. Murphy625

    Murphy625 Member

    Messages:
    150
    Location:
    Michigan
    Yes.. 200 max on each leg.
    No. Breakers can total far more than the mains. The mains are protected by their own breaker. It is assumed that you will never draw the maximum current on every breaker simultaneously. If you did, the main breaker on a mains panel, or the feeder circuit breaker on a main lug panel would trip.

    Always remember, breakers are not there to protect the devices. Breakers are only meant to protect the wires.

    Hope that helps,
  3. JMingrone

    JMingrone New Member

    Messages:
    49
    Location:
    Connecticut
    Great, thanks!
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,273
    Location:
    New England
    It might be an issue if the panel was full of breakers and you had lots of heavy use appliances in the home, other than that, not a problem. For example, say you had multiple, big water heaters, big a/c units, a pool heater, a commercial style 8-pot stove and multiple ovens...then 200A may not be adequate. This isn't an issue for the vast majority of people...
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,062
    Location:
    Cave Creek, Arizona
    It could also be a problem if you had ALL the high draw 120v items, such as microwave, space heaters, blow dryers, etc., all on the same leg of the feed and they all operated simultaneously at the same time as the major 240v ones, such as A/C units, water heaters, pump, and oven, which although unlikely could happen at some time.
    Last edited: Jul 18, 2013
  6. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,454
    Location:
    Houston, TX

    That is Exactly how a lot of Inspectors Test here, when you are buying a house.

    But they are the Good ones, and you pay well for a good inspection.


    Good Luck.
  7. Murphy625

    Murphy625 Member

    Messages:
    150
    Location:
    Michigan
    Ok.. I'll bite..
    The way I'm reading your reply, it seems that you're implying that drawing too many amps on one leg is somehow more detrimental than drawing too many amps equally on both legs.

    What difference does it make?

    And for the sake of this discussion, lets leave out the theoretical voltage drop issues.
  8. ActionDave

    ActionDave Electrician

    Messages:
    361
    Location:
    Colorado
    There is no way to draw 200A on one leg of a house unless it was your sole mission in life.
  9. leejosepho

    leejosepho DIY scratch-pad engineer

    No, I think his point is simply that an overload could happen more easily and trip a main breaker "if you had ALL the high draw 120v items, such as microwave, space heaters, blow dryers, etc., all on the same leg of the feed and they all operated simultaneously at the same time as the major 240v ones, such as A/C units, water heaters, pump, and oven". Balanced loads seem better overall.
    Last edited: Jul 22, 2013
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,062
    Location:
    Cave Creek, Arizona
    An overload on EITHER leg will trip the main breaker, but it would be more difficult to overload both of them at the same time, unless the service were seriously undersized, (I have seen houses with 400 amp systems). The ideal is to have the two legs so well balanced that you would not need the neutral, but that would only happen in a Utopian system.
  11. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    Completely agree.
    It is also nearly impossible to balance the load in a residential application. The loads are so transient that it's not worth trying.
    Just fill the panel with circuits and you'll be as balanced as you could ever be.
  12. ActionDave

    ActionDave Electrician

    Messages:
    361
    Location:
    Colorado
    Completely agree with you on this point. Time for a man hug?
    Last edited: Jul 22, 2013
  13. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,454
    Location:
    Houston, TX
    I don't think Load Balancing is a big problem in a home, if it is wired correctly.

    I have seen 3 phase systems that required it, or it would trip a ground fault.


    Be careful playing with electricity, and have fun doing it.
Similar Threads: Basic electric
Forum Title Date
Electrical Forum discussion & Blog Basic electrical questions Aug 30, 2009
Electrical Forum discussion & Blog Basic Electrical Diagram Oct 17, 2007
Electrical Forum discussion & Blog switching 15-amp to 20-amp (basic Q's) Sep 26, 2008
Electrical Forum discussion & Blog Basic Wiring Question Aug 6, 2008
Electrical Forum discussion & Blog Circuit Planning Basics Nov 5, 2007

Share This Page