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#90087 10/30/04 07:30 AM
Joined: Jun 2004
Posts: 613
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I've seen some of these generator back-up systems for residential(optional backup supply),either manual or automatic, some with more than 6 circuits with no main disconnect in the equipment.If they are hard wired are'nt we required to install a main disconnect for the power supply according to 225.31?
I was looking at some of the equipment and installation instructions on www.gen-tran.com and there is no mention of installing a main disconnect.
The installation that I am designing will locate the generator remote from the dwelling behind a detached garage.

shortcircuit

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#90088 10/30/04 07:36 AM
Joined: Jan 2003
Posts: 4,391
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I have not seen a generator come without an overcurrent device mounted on it that can serve as the disconnecting means.

Also 225.21 is not the section to look at, go to 445.18

Quote
445.18 Disconnecting Means Required for Generators.

Generators shall be equipped with a disconnect by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator except where:

(1)The driving means for the generator can be readily shut down; and

(2)The generator is not arranged to operate in parallel with another generator or other source of voltage.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#90089 10/30/04 08:17 AM
Joined: Jun 2004
Posts: 613
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Member
Iwire...I am aware that a generator has a disconnect interigal with the unit, but when installed remote as described wouldn't the supply require an additional disconnecting means where it enters the building as described in 225.31

shortcircuit

#90090 10/30/04 08:43 AM
Joined: Jan 2003
Posts: 4,391
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Moderator
shortcircuit

Quote
but when installed remote as described wouldn't the supply require an additional disconnecting means

How remote is remote? [Linked Image]

Quote
225.32 Location.
The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall be permitted to be utilized.

IMO, If the generators built in disconnect is readily accessible and located next to the building it serves 225.32 has been satisfied.

IMO it is up to the inspector to determine how far from the building the disconnect can be located. This to me is no different than 230.70(A)(1) for services.

"nearest the point of entrance"

Is always open to interpretation, at least that is how it goes in the area I work. [Linked Image]

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#90091 10/30/04 09:01 AM
Joined: Jun 2004
Posts: 206
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shortcircuit & iwire If you are doing this in MA. 527 CMR 12.00 2002 Massachusetts Electrical Code 225.32 requires this disconnect to be within 10' of the building or structure served. Mass always has to throw their 2 cents into the mix.

Al

#90092 10/30/04 10:38 AM
Joined: Jun 2004
Posts: 613
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The generator will be located behind a detached garage 60 feet away and out of sight completely of the house it will be back feeding. PVC will be run under ground through the concrete foundation to the automatic transfer equipment...which has no main disconnect and is equiped with more than 6 overcurrent devices.

According to capt al's post and 225.31...it seems to require additional disconnecting means...right?

shortcircuit

thanx for your help!

#90093 10/30/04 12:04 PM
Joined: Jun 2004
Posts: 206
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Member
shortcircuit, I would say yes. I would install a disconnect switch before the ATS. Now you have met the requirements of NEC 225.31 & MEC 225.32.

Al

#90094 10/31/04 07:34 PM
Joined: Jun 2004
Posts: 220
T
Member
I would say no to the extra disconnect, if this not a whole panel transfer. the generator disconnect is outside the buildng it is serving, just as a disco on pole is outside a building it is serving. I was at factory training a year ago, and they never mentioned extra disco ahead of there box. As a matter of fact, if you alter their system in anyway, you would void the warranty.


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