ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
power failure but lights dim
by gfretwell - 08/14/20 04:16 PM
HVDC Greece to Crete
by gfretwell - 08/06/20 02:28 AM
310.15 (B) 7 Feeders
by HotLine1 - 07/31/20 02:29 PM
What would be the ideal solution?
by Fleppin - 07/21/20 12:42 AM
NESC question
by gfretwell - 07/16/20 04:17 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 19 guests, and 19 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
main breaker for subpanel #93774 06/14/05 09:07 PM
Joined: Aug 2001
Posts: 457
J
Jim M Offline OP
Member
I just got a red tag for not having a main in a subpanel in a residential detached garage. Panel is a C-H 4/8 MLO with 2 circuits installed. AHJ is using 225-31 as the reason.

Is anyone elses area requiring this. I guess I was thinking 6 or less breakers did not need a main.

2017 / 2014 NEC & Related Books and Study Guides
Re: main breaker for subpanel #93775 06/14/05 09:14 PM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
In my opinion you are correct.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: main breaker for subpanel #93776 06/14/05 09:15 PM
Joined: Jul 2004
Posts: 9,514
G
gfretwell Offline
Member
225.33(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.


Greg Fretwell
Re: main breaker for subpanel #93777 06/15/05 12:29 AM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Member
For a separate building, such as a detached garage, you are required to have a disconnecting means on the building. In this area, I typically have a 'safety switch' mounted on the outside, feeding the panel directly behind it (on the inside). A 'main breaker' in the panel is another way to do it- but is usually more expensive- and our AHJ likes the disconnect on the outside anyway.

There is one exception- no such disconnect is necessary if you're running only one circuit- and "circuit" is vague enough to include a single multi-wire branch circuit (or what we normally think of as two circuits). Assuming that you are using both full-size breaker spaces for a pair of full size breakers, you might be able to argue that you have but a single multi-wire circuit, with the breakers simpling being an additional, not required, disconnecting means.

Re: main breaker for subpanel #93778 06/15/05 02:35 PM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
IMO (and that of the Handbook) 225 section II effectively says to treat each separate building like it has it's own service entrance. Except when only one circuit (specifically allows multi-wire) is in the separate building.

225.30 only one source can feed the separate building (230.2, 230.40)
225.31 all ungrounded conductors must be disconnected (230.70)
225.32 disconnect where power enters building (230.71(A))
225.33 number of mains (230.71)
225.34 group the mains (230.72)
225.35 accessible to occupants (230.70(A)(1), 230.72(C))
225.36 suitable for service entrance(230.70(C))

Re: main breaker for subpanel #93779 06/15/05 03:39 PM
Joined: Jul 2004
Posts: 9,514
G
gfretwell Offline
Member
Don't ignore 225.36 exception
Exception: For garages and outbuildings on residential property, a snap switch or a set of 3-way or 4-way snap switches shall be permitted as the disconnecting means.


Greg Fretwell
Re: main breaker for subpanel #93780 06/15/05 07:02 PM
Joined: Jan 2005
Posts: 315
L
luckyshadow Offline
Member
Where I live if the sub panel is in a ATTACHED garage no main needed - in a DETACHED garage a main is required by ahj

Re: main breaker for subpanel #93781 06/15/05 08:23 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Member
Thank you, JBD, for taking the time to break down all the code citations I was alluding to!


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Grover
Grover
Sebago, ME, USA
Posts: 109
Joined: January 2005
Show All Member Profiles 
Top Posters(30 Days)
BigB 2
wa2ise 1
Popular Topics(Views)
268,663 Are you busy
202,998 Re: Forum
191,363 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3