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generator disconnect #90087
10/30/04 06:30 AM
10/30/04 06:30 AM
S
shortcircuit  Offline OP
Member
Joined: Jun 2004
Posts: 608
massachusetts
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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Re: generator disconnect #90088
10/30/04 06:36 AM
10/30/04 06:36 AM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
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
Re: generator disconnect #90089
10/30/04 07:17 AM
10/30/04 07:17 AM
S
shortcircuit  Offline OP
Member
Joined: Jun 2004
Posts: 608
massachusetts
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

Re: generator disconnect #90090
10/30/04 07:43 AM
10/30/04 07:43 AM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
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
Re: generator disconnect #90091
10/30/04 08:01 AM
10/30/04 08:01 AM
C
capt al  Offline
Member
Joined: Jun 2004
Posts: 206
Norton, Ma USA
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

Re: generator disconnect #90092
10/30/04 09:38 AM
10/30/04 09:38 AM
S
shortcircuit  Offline OP
Member
Joined: Jun 2004
Posts: 608
massachusetts
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!

Re: generator disconnect #90093
10/30/04 11:04 AM
10/30/04 11:04 AM
C
capt al  Offline
Member
Joined: Jun 2004
Posts: 206
Norton, Ma USA
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

Re: generator disconnect #90094
10/31/04 06:34 PM
10/31/04 06:34 PM
T
trekkie76  Offline
Member
Joined: Jun 2004
Posts: 220
baileyville, maine, usa
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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