Sizing feeder ocpd and wire for 125amp rated subpanel/panel board in detached garage

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jwelectric

Senior Member
Location
North Carolina
Code reference please.
225.33 Maximum Number of Disconnects.
(A) General. The disconnecting means for each supply permitted by 225.30 shall consist of not more than six switches or six circuit breakers mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard.
There shall be no more than six disconnects per supply grouped in any one location.

Exception: For the purposes of this section, disconnecting means used solely for the control circuit of the ground-fault protection system, or the control circuit of the power operated supply disconnecting means, installed as part of the listed equipment, shall not be considered a supply disconnecting means.

(B) Single-Pole Units. Two or three single-pole switches or breakers capable of individual operation shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with identified handle ties or a master handle to disconnect all ungrounded conductors with no more than six operations of the hand.

The number of spaces has nothing to do with the installation, only the number of breakers installed. In a 42 circuit panel with only 6 breakers would be code compliant.
It is possible to take a 6 circuit panel and install 12 overcurrent devices

 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
building only has three breakers, wouldn't the six disconnect rule apply?
Under the 2014 code, yes. Under previous codes, probably not. The previous codes required that the second building disconnect be suitable for use as service equipment. The listing for many load centers say that they are only suitable for use as service equipment where a main breaker has been installed in the load center.
 

jumper

Senior Member
Under the 2014 code, yes. Under previous codes, probably not. The previous codes required that the second building disconnect be suitable for use as service equipment. The listing for many load centers say that they are only suitable for use as service equipment where a main breaker has been installed in the load center.

Ooops, I forgot about that.:ashamed1:
 

kingpb

Senior Member
Location
SE USA as far as you can go
Occupation
Engineer, Registered
Based on the location, they probably assume the panel in the garage is going to be loaded up running a bunch of grow lights so they want it full capacity. :thumbsup:
 

kwired

Electron manager
Location
NE Nebraska
Good evening,
I am a Nevada County Building Inspector in CA. I had this come up twice today in consecutive inspections. A detached garage is fed from the main service panel with a 2 pole 40 amp breaker and 2 #8cu plus neutral and ground. The panel board in the garage has 2 20 amp breakers for outlets and 1 15 amp breaker for lights. The branch circuits are sized correctly. I am being told that the ocpd and feeder wires from the house to the garage must be sized to the rating of the panel board in the garage which is 125 amps. At 100' distance from house to garage this is approx a #1 cu. This guy only installed a 3/4" conduit. Do I size to the load or the panel board rating? And if its to the panel board rating must is be equal to or greater to the panel board rating or must it be less then?

Nothing in NEC prevents you from supplying 2000 amp gear with only a 60 amp conductor if the load is 60 amps or less. The 2000 amp gear would seem cost prohibitive in most cases for that size of load, but I guess if you just had it laying around maybe it is worth using.

125 amp panels are used all the time for lesser capacity. Not many panelboards with a 40 amp rating out there for one thing. I can think of one but it is only a two space loadcenter, and even when I use that particular panel it is often for limited/specific load applications and maybe only gets a 15-30 amp breaker installed.
 

klineelectric

Member
Location
FL
Occupation
electrical contractor
Mike, I was questioning kliens statement about the panel could only have 6 spaces.

You are correct, says nothing about spaces in code. It says 6 breakers or switches. With that being said I would not pass and have failed in the past for having more than 6 spaces without a main, in four surrounding counties. Was told on more than one occasion that the "authority has jurisdiction", so I stopped arguing. I choose my battles carefully. For the cost of a main its not worth pissing off a guy who will be inspecting future jobs. I will check code section before future posts. LOL . That's why I continue to use this forum because of all of the knowledgeable people on here. :)
 

templdl

Senior Member
Location
Wisconsin
You are correct, says nothing about spaces in code. It says 6 breakers or switches. With that being said I would not pass and have failed in the past for having more than 6 spaces without a main, in four surrounding counties. Was told on more than one occasion that the "authority has jurisdiction", so I stopped arguing. I choose my battles carefully. For the cost of a main its not worth pissing off a guy who will be inspecting future jobs. I will check code section before future posts. LOL . That's why I continue to use this forum because of all of the knowledgeable people on here. :)

My thoughts also. I would rather provide a main as there is no question about guessing which circuit needs to be sdhut of in a hurry.
 

norcal

Senior Member
Under the 2014 code, yes. Under previous codes, probably not. The previous codes required that the second building disconnect be suitable for use as service equipment. The listing for many load centers say that they are only suitable for use as service equipment where a main breaker has been installed in the load center.

CA is on the 2011 NEC.
 
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