(206) 949-5683, Top Rated Plumber, Seattle
Page 1 of 2 12 LastLast
Results 1 to 15 of 20

Thread: Is there a 200 amp breaker box with 100 amp main

  1. #1
    DIY Member rayh78's Avatar
    Join Date
    Sep 2008
    Location
    Virginia
    Posts
    77

    Default Is there a 200 amp breaker box with 100 amp main

    Have a remodel to do and will sub out electrical.
    Electrician I have used in the past said I cant do this.
    Years ago I had the same situation. Small house with 100 amp service and customer does not want to pay for upgrade now but wants breakers. Instead of putting in just a 100 amp breaker box, I had a 200 amp Murray box put in and install a 100 amp main breaker instead of a 200 amp main. The box was still 200 amp to make a future upgrade easier. A murray 100 amp breaker fit in the same space as a 200 amp for the Murray brand. Which was not the same with square D. Since then if ever I contracted out any electrical we have used square D brand. But have this situation again and they dont make murray anymore. Is there another brand out there?
    Electrician does not want to do this either. Use just a square D 200 amp box with a 100 amp square D line feed breaker because he saids maybe a problem with inspector.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,405

    Default

    I'm by no means a pro, but it is my understanding that as long as the supply line capacity is not exceeded by the protection circuit, it is okay to use a smaller cb. Now, with more available slots, you are more likely to be able to trip the main breaker, but that's another issue. Logically, but maybe not by code, it should be in the same idea as using 12g wire on a 15A service, which could also use 14g. The wire size determines the maximum current that can be drawn.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Senior Robin Hood Guy Ian Gills's Avatar
    Join Date
    Jul 2007
    Location
    USA
    Posts
    2,781

    Default

    You need to convince the customer that they are mad.

    When I tried to do the opposite (upgrade the service but not the panel) the extra cost of calling out an electrician just to do the panel in the future would have been much more than the modest increment I ended up paying to get it all done in one go.

    Not to mention the requirement for another inspection.

    Refuse.

  4. #4
    DIY Member rayh78's Avatar
    Join Date
    Sep 2008
    Location
    Virginia
    Posts
    77

    Default

    Alittle more info.
    This is a small 600 sq.ft. guest house on a seperate meter and has gas heat.
    So it is questionable if an upgrade would ever be needed but they would like the option. And it would save some work. And the price difference between a 100 amp or 200 amp box is not that great.
    Would save morethan that if ever an upgrade

  5. #5
    Electrical Contractor Jim Port's Avatar
    Join Date
    Aug 2009
    Location
    Maryland
    Posts
    156

    Default

    I can see no logical reason to think about installing any more than a 100 amp panel for a 500 square foot house.

  6. #6
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,653

    Default

    What is feeding this panel? If it is a subpanel, just install the 200 amp unit with a 100 amp breaker at the main panel. if it is being metered, the electric company can install new cables and meter, or just a 200 amp meter if their wires are adequate.

  7. #7
    General Engineering Contractor ballvalve's Avatar
    Join Date
    Dec 2009
    Location
    northfork, california
    Posts
    3,261

    Default

    600 sq feet with gas and 200 amps? Going to smelt aluminum?

    60 amps is plenty like every three bedroom house had until 1970...

    You can use a 100 amp panel and feed it with a 50 amp breaker, and I'll bet it NEVER trips.

    200 amps is absurd unless they plan to add 4 more 600' units to this one.
    Last edited by ballvalve; 10-10-2010 at 12:01 AM.

  8. #8
    DIY Member rayh78's Avatar
    Join Date
    Sep 2008
    Location
    Virginia
    Posts
    77

    Default

    still has electric hot water and stove and the long term possiablity was to switch to a heatpump

  9. #9
    Electrical Contractor Jim Port's Avatar
    Join Date
    Aug 2009
    Location
    Maryland
    Posts
    156

    Default

    If you switch to a heat pump stay with the gas for the backup heat.

  10. #10
    General Engineering Contractor ballvalve's Avatar
    Join Date
    Dec 2009
    Location
    northfork, california
    Posts
    3,261

    Default

    You could feed 200 amp sub panel with a 100 amp breaker but should size wire for the 200 amps.

  11. #11
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,653

    Default

    Goes without saying if this is for a future upgrade, otherwise the whole discussion is irrelevent.

  12. #12
    DIY Member rayh78's Avatar
    Join Date
    Sep 2008
    Location
    Virginia
    Posts
    77

    Default

    Would use the same wire for now. Just so I understand options.
    It would be against code to use 200 amp box. Blank off cover space for the factory main breaker and then use 100 amp line feed breaker.
    thanks

  13. #13
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,653

    Default

    You can use any panel you want, with or without the main breaker, as long as the breaker feeding it is appropriate for the wire to the panel. Although you might have a bit of difficulty attaching the wires to the buses without going through a main breaker.

  14. #14
    Electrical Contractor Jim Port's Avatar
    Join Date
    Aug 2009
    Location
    Maryland
    Posts
    156

    Default

    If you decide to backfeed the breaker you will need to install a breaker hold-down kit.

  15. #15
    DIY Member TWEAK's Avatar
    Join Date
    May 2009
    Location
    Bay Area CA
    Posts
    83

    Default

    Does the guest house have its own independant service entrance? Or is it a sub panel fed off the main house panel?
    Last edited by TWEAK; 10-16-2010 at 08:44 PM.

Similar Threads

  1. Main breaker box clearance
    By ktambascio in forum Electrical Forum discussion & Blog
    Replies: 2
    Last Post: 07-01-2009, 06:12 PM
  2. Main Breaker Tripping
    By Dunbar Plumbing in forum Electrical Forum discussion & Blog
    Replies: 2
    Last Post: 01-08-2009, 03:39 PM
  3. PUMP can effect to main circuit breaker get trip?
    By chomnap in forum Pumps and Tanks Well Forum & Blog
    Replies: 5
    Last Post: 12-09-2008, 05:34 AM
  4. Main Circuit Breaker Panel Humms
    By edstevn in forum Electrical Forum discussion & Blog
    Replies: 2
    Last Post: 12-02-2008, 07:29 AM
  5. Sprinkler Air Vacuum breaker vs Pressure vacuum breaker
    By Mike Pascutiu in forum Irrigation / Sprinkler Forum
    Replies: 15
    Last Post: 05-28-2005, 01:47 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
  •