(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 13 of 13

Thread: Basic electric service panel questions

  1. #1
    DIY Member JMingrone's Avatar
    Join Date
    Aug 2006
    Location
    Connecticut
    Posts
    49

    Default Basic electric service panel questions

    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. #2
    DIY Senior Member Murphy625's Avatar
    Join Date
    Jul 2013
    Location
    Michigan
    Posts
    147

    Default

    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. #3
    DIY Member JMingrone's Avatar
    Join Date
    Aug 2006
    Location
    Connecticut
    Posts
    49

    Default

    Great, thanks!

  4. #4
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,382

    Default

    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...
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  5. #5
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,615

    Default

    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 by hj; 07-18-2013 at 07:22 AM.
    Licensed residential and commercial plumber

  6. #6
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,642

    Default

    Quote Originally Posted by hj View Post
    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.

    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.
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

  7. #7
    DIY Senior Member Murphy625's Avatar
    Join Date
    Jul 2013
    Location
    Michigan
    Posts
    147

    Default

    Quote Originally Posted by hj View Post
    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.
    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. #8
    Electrician ActionDave's Avatar
    Join Date
    Feb 2009
    Location
    Colorado
    Posts
    326

    Default

    There is no way to draw 200A on one leg of a house unless it was your sole mission in life.

  9. #9
    DIY scratch-pad engineer leejosepho's Avatar
    Join Date
    Nov 2006
    Location
    200 miles south of Little Rock
    Posts
    2,474

    Default

    Quote Originally Posted by Murphy625 View Post
    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.
    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.
    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 by leejosepho; 07-22-2013 at 03:36 AM.
    "Great minds discuss ideas, average minds discuss events and small minds discuss people." --Eleanor Roosevelt

  10. #10
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,615

    Default

    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.
    Licensed residential and commercial plumber

  11. #11
    Licensed Electrical Contractor Speedy Petey's Avatar
    Join Date
    Jun 2007
    Location
    NY State, USA
    Posts
    975

    Default

    Quote Originally Posted by ActionDave View Post
    There is no way to draw 200A on one leg of a house unless it was your sole mission in life.
    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. #12
    Electrician ActionDave's Avatar
    Join Date
    Feb 2009
    Location
    Colorado
    Posts
    326

    Default

    Quote Originally Posted by Speedy Petey View Post
    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.
    Completely agree with you on this point. Time for a man hug?
    Last edited by ActionDave; 07-22-2013 at 10:25 PM.

  13. #13
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,642

    Default

    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.
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

Similar Threads

  1. Service Panel Change Out.. Need Help Determining and Sizing Panel
    By Mike Pastorelli in forum Electrical Forum discussion & Blog
    Replies: 3
    Last Post: 05-29-2013, 03:08 AM
  2. My Sub-Panel set-up and general electric questions... Good to go?
    By Mike Pastorelli in forum Electrical Forum discussion & Blog
    Replies: 10
    Last Post: 05-27-2013, 10:22 AM
  3. GFCIs in the service panel? How many circuits?
    By bobwilli in forum Electrical Forum discussion & Blog
    Replies: 7
    Last Post: 11-24-2009, 06:26 AM
  4. New Service Panel Question
    By jparrie in forum Electrical Forum discussion & Blog
    Replies: 12
    Last Post: 05-27-2008, 02:53 PM
  5. Main lug as a primary service panel
    By madpenguin in forum Electrical Forum discussion & Blog
    Replies: 4
    Last Post: 01-06-2008, 07:52 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •