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#88972 - 08/19/04 06:21 PM disconnect at detached garage
shortcircuit Offline

Registered: 06/27/04
Posts: 608
Loc: massachusetts
Would I be correct to say that a detached garage on the same property as a one family dwelling with one feeder run to it as required by 225.30 shall have a disconnecting means out at the garage to shut down the sub-panel and that the minimum size of that feeder can't be smaller than 60 amp as required by 225.39(D)where the building will have more than 2 branch circuits???

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#88973 - 08/19/04 07:47 PM Re: disconnect at detached garage
gfretwell Offline


Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
Yes on the disconnect. On the 225.39(D) issue, that just says the "disconnect" has to be able to open 60a, not that the feeder itself has to be 60a.
Clear as mud huh?
Greg Fretwell

#88974 - 08/20/04 02:49 AM Re: disconnect at detached garage
shortcircuit Offline

Registered: 06/27/04
Posts: 608
Loc: massachusetts
The disconnect that is required by 225.31 must also be "suitable for use as service equipment" as stated in would a 20 circuit main lug panelboard with the feeder connected to a 60 amp 2-pole breaker pluged into the buss be considered as suitable as service equipment or should a listed main breaker panelboard be used at the detached garage?

#88975 - 08/20/04 03:14 AM Re: disconnect at detached garage
iwire Offline

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Your good to go with the back fed 60 as long as you remember to secure the breaker in place.

Also if you are installing a total of less than 6 breakers you can forget about the back fed 60.

Up to 6 throws of the hand can be the disconnect, regardless of the panel size.

Bob Badger
Construction & Maintenance Electrician

#88976 - 08/20/04 03:23 AM Re: disconnect at detached garage
shortcircuit Offline

Registered: 06/27/04
Posts: 608
Loc: massachusetts
Hi the 60 amp backfeed main should be bolted in place...but the 6 breakers or less don't need to be bolted in place?


#88977 - 08/20/04 03:39 AM Re: disconnect at detached garage
cpal Offline

Registered: 05/17/04
Posts: 165
Loc: Cohasset MA
AS Bob said
if a device is back fed it must be secured to avoid poping out if the panel cover is removed for service.

408.16 (F) Back-Fed Devices. Plug-in-type overcurrent protection devices or plug-in type-main lug assemblies that are backfed and used to terminate field-installed ungrounded supply conductors shall be secured in place by an additional fastener that requires other than a pull to release the device from the mounting means on the panel.

Don't for get the requirements for gounding second buildings or structures, Article 250.32. Esp if you have interconnecting metal raceways or water piping)

do you need 20 circuits??

[This message has been edited by cpal (edited 08-20-2004).]

#88978 - 08/20/04 04:12 AM Re: disconnect at detached garage
shortcircuit Offline

Registered: 06/27/04
Posts: 608
Loc: massachusetts
Hey cpal...OK I understand about bolting in the main and the grounding requirements...but what about the 6 breakers as the disconnecting means...they need not be bolted in as you describe above?A 20 circuit panel will be used.

thanx, shortcircuit

#88979 - 08/20/04 04:31 AM Re: disconnect at detached garage
n1ist Offline

Registered: 02/13/02
Posts: 176
Loc: Malden MA
The bolting is to prevent the breaker from being pulled off and having live clips on the rear. In the 6-throws situation, the bus is live but if you remove a breaker, the breaker is dead.

#88980 - 08/20/04 07:43 AM Re: disconnect at detached garage
tdhorne Offline

Registered: 03/22/01
Posts: 344
Loc: Maryland, USA
In ordert to use a back fed breaker as the required building disconnecting means the panel must be listed as service equipment with a back fed breaker. Check the panels labeling that it is listed in that configuration.
Tom Horne
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison

#88981 - 08/20/04 09:21 AM Re: disconnect at detached garage
Buck33k Offline
Junior Member

Registered: 06/22/04
Posts: 7
Loc: Washington
It is true that you can forget about the backfed main with 6 breakers or less but only if it is not a lighting and appliance branch circuit panel board. 408.16(A) Correct? or does exception 1 change this?

[This message has been edited by Buck33k (edited 08-20-2004).]

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