crct. brkr. pnl. dillema

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Old 09-12-00, 03:47 PM
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For five years I have been wanting to replace my service that is 40 years old to eliminate an inadequate fuse panel and other problems that revolve around that problem. I know all about how to replace the panel and such, but I plan to hire a professional anyway to get the job done since I never have enough tome to do such time consuming projects all at once.
The first step was to buy a panel, which would be connected the existing 100A underground service from the road. A requirement I had was that the panel had to be a Square D QO series panel with no <30 spaces. "A 150A or 200A panel with 30 spaces could be backfed with a 100A breaker" was the plan an electrician aquantance had. I found something better (at first), Lowe's carries a Square D QO series 100A 32 space panel.
I have prepared the panel for installation-KO's removed, clamps installed, circuit breakers installed, etc.
To my dismay, I called an electrician and explained the situation, however was told he would not install the $275(with breakers) panel. The reason was that the main breaker would have to be 150A min. because there are 30 spaces for him to install it.
I do not want to throw away a $150 panel.

WHAT CAN I DO WITH THIS PANEL?
I HAVE NOT BEEN SUCESSFUL IN LOCATING THE ARTICLE IN THE 1999 NEC THAT CONTAINS THE REQUIREMENTS FOR SERVICE SIZE TO A GIVEN PANEL IN RELATIONSHIP TO ITS QUANTITY OF CIRCUITS OR CIRUIT BREAKERS. CAN SOMEBODY PINPOINT THE ARTICLE THAT CONTAINS THIS INFORMATION?
I HOPE TO HAVE THIS INSTALATION COMPLETE BY WINTER, GIVEN THAT WHERE I AM, THERE WILL A BAD WINTER THIS YEAR AND I WILL NEED TO PLUG OUR NEW SNOWBLOWER INTO THE SHED (now wired) THAT WAS ONE OF THE ORIGINATING PURPOSES OF REPLACING THE SERVICE PANEL (to add circuits both inside and outside the house).
 
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Old 09-12-00, 05:34 PM
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Its my recollection that I answered a very similar question not long ago.
The short answer is that there is nothing in the code on this requirment.
However, the code may not be the problem for you. The electrician may know something here that we don't or you didn't understand correctly.
In that, your local authority may have addendums to the code which restrict this type of thing. Either the wire must be rated the same as the panel with same size main or no backfeeding, or he may have taken a quick load calc and saw that you either are or will be overloaded on a 100 amp panel. Your connected load can only be 80 amps. If you have an average size home fully electric, including heat you have a potential bigger problem.
My suggestion is to contact your local authorities and find out what, if any, requirements need to be met. you can also contact another electrician to get his viewpoint.
I might add one other comment, you can take it for what it is worth.
Currently, I do not do any work where the owner gets the electrical material for jobs of this nature. Invariably they do not have the right parts or don't have specific parts at all. I did it formerly, but only on a T basis untill I had a problem with this arrangement. This may be the real reason the electrician left and just needed a more plausible, better reason to give to you.
 
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Old 09-13-00, 03:43 PM
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David B is right on most of his reply. Especially of the reluctance of an electrician not wanting to use customer boght material. Too much risk of complication and material not compatible with other materials, or the overall design

I disagree on his statement of the 80% maximum requirement in a dwelling. The NEC says that you can load anything and everthing in a dwelling at 100% because the dwelling is not considered commercial. Overcurrent devices of Motors loads however are limited to the 80% max even in a home.

The main breaker in a dwelling is a service dictated in size by the damand load calculation as required in article 220. This demand load is the minimum size main service you are allowed in a dwelling rated at 100% demand factor.

The article that you were looking for is 384-15 stating that 42 circuits is the maximum number of circuit allowed in a panel or switch board. There used to be a limit of 20 circuits stated in the code for 100 amp rated panels but it is my understanding that this 20 circuit limit on 100 amp panels was deleted and the limitation of the maximum number of circuits in a panel is now governed by the UL listing. Article 110-3-b of the NEC requires that all equipment is listed and labeled. I believe that if you check on your panel door, the panel you mentioned is both listed and labled by Under Writers Labrotory. The UL with an r in the bottom right corner of this label verifies that your panel is approved by Under Writers Labrotory has approved the design and use of your panel in the electrical industry.

In most states it is required that if a local jurisdiction has a local set of Codes, these Codes must exceed the NEC and must be approved by the State of the Jurisdiction before a local AHJ can enforce local Codes.

Check with you AHJ to confirm approval of that panel and that it is of sufficient size to serve your dwelling as a main service panel.

BobbyD is right on track except the 80% on the breaker.

Good Luck

Wg
 
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