Results 1 to 8 of 8
  1. #1
    Join Date
    Sep 2008
    Location
    so so, California
    Posts
    1,769

    Default Service equipment and sub panel(s) question

    I have a service panel rated for 125A and it has in it, a 100A main breaker and a 100A breaker for 1 sub and another (30A) below that to another sub. I was under the assumption that the subs cannot exceed 80% of the panel's max. Your thoughts please. thanks.

    Similar Threads:
    Last edited by Marc M; 01-18-2010 at 09:04 PM.
    Inspection Referral SOC

  2. #2
    Fred Warner's Avatar
    Fred Warner Guest

    Default Re: Service equipment and sub panel(s) question

    Quote Originally Posted by Marc M View Post
    I have a service panel rated for 125A and it has in it, a 100A main breaker and a 100A breaker for 1 sub and another (30A) below that to another sub. I was under the assumption that the subs cannot exceed 80% of the panel's max. Your thoughts please. thanks.
    Urban Myth.


  3. #3
    Join Date
    Feb 2008
    Location
    Chicago IL
    Posts
    1,984

    Default Re: Service equipment and sub panel(s) question

    Oh no, you used the 'sub' word. Jerry's going to get you.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  4. #4
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: Service equipment and sub panel(s) question

    Quote Originally Posted by Marc M View Post
    I was under the assumption that the subs cannot exceed 80% of the
    Subs should not exceed 100% of their rated depth, beyond that depth they enter into the 'dead zone'.

    Fred is correct, of course.

    You could have service equipment with a disconnect rated at 100 amps and a remote panel rated at 400 amps, it will not matter, no way are you going to get 400 amps through that 100 amp main to the 400 amp rated panel (unless the overcurrent disconnect is inoperative for whatever reason, such as being an FPE, in which case it is entirely likely ).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5
    Join Date
    Mar 2009
    Location
    Colorado Front Range
    Posts
    601

    Default Re: Service equipment and sub panel(s) question

    If a service panel has feed through lugs a sub panel can have the same rating as the service panel. The size of any additional panels is limited by the maximum rating of allowable branch breakers.

    The above doesn't limit the size of a main breaker in the sub panels. There would be no reason that a sub panel with a 200 AMP main breaker can't be fed from a service panel with a 150 AMP rating.


  6. #6
    Join Date
    Sep 2008
    Location
    so so, California
    Posts
    1,769

    Default Re: Service equipment and sub panel(s) question

    you guys are funny. Yea, I caught myself on the "sub" word but it was too late. I understand now, I should have thought this one out before posting.


  7. #7
    Join Date
    Mar 2007
    Location
    Philadelphia PA
    Posts
    3,177

    Default Re: Service equipment and sub panel(s) question

    I think Brian should install an automatic pop-up warning whenever anyone tries to use the term sub-panel.
    A loud siren might help, too.

    "There is no exception to the rule that every rule has an exception." -James Thurber, writer and cartoonist (1894-1961)
    www.ArnoldHomeInspections.com

  8. #8
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: Service equipment and sub panel(s) question

    Quote Originally Posted by Bill Kriegh View Post
    If a service panel has feed through lugs a sub panel can have the same rating as the service panel. The size of any additional panels is limited by the maximum rating of allowable branch breakers.
    Incorrect.

    The size of remote panels can be as high of rating as one likes, regardless of the size of the overcurrent protection protecting it - as long as it is *at least* the rating of the overcurrent protection.

    Other incorrect and insufficient information in the other part too.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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
  •