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#97992 - 04/23/06 08:39 AM GFPE/Feeder
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Does a feeder taped from a customer owned transformer require GFPE? 480/277v. 1000a. And with the xformer located outside can the GFPE (if needed) be located in the building?
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#97993 - 04/23/06 09:14 AM Re: GFPE/Feeder
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
I don't think it's a feeder.

It's a tap until it gets to the OCPD.

Once at the OCPD 215.10 would become relevant.

JMO, Bob
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Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#97994 - 04/23/06 09:31 AM Re: GFPE/Feeder
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Bob- I think it's a feeder because of the definition in 100. IMHO.
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#97995 - 04/23/06 10:50 AM Re: GFPE/Feeder
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
I see your point about the definition.

However I think it is reasonable to assume that GFP is not required any sooner than OCP on the secondary side of a transformer. (ie-taps rules)

If we do not assume that than no transformer with an Wye output greater than 1000 amps can be used.

If we say 25', 50' or even a 100' is to far than 1" is also to far as there is no direction to follow other than the transformer tap rules.
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#97996 - 04/23/06 11:43 AM Re: GFPE/Feeder
winnie Offline
Member

Registered: 09/15/03
Posts: 652
Loc: boston, ma
I'm not really in a position to comment on the code analysis; I don't see why conductors applied under tap rules to a panelboard are not also considered feeders, but see how this leads to some strange interpretations of the GFP requirements.

However the primary side of the transformer requires overcurrent protection, so in theory your ground fault protection relaying could be applied on the _primary_ side, as long as the CT or ground fault detection was on the _secondary_ side.

I don't know if there are any CTs available which can be mounted in the field wiring space of the transformer itself. I also don't know what other codes would be violated if you mount such hardware inside the transformer enclosure. But the ground fault relay and shunt trip module on the primary side would permit ground fault protection of the secondary side feeder tap with small percentage increase in cost versus placing the ground fault sensors and relay and shunt trip module at the OCPD end of the 'feeder tap'.

-Jon

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#97997 - 04/23/06 02:46 PM Re: GFPE/Feeder
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Winnie & Bob- First of all, this is an actual installation in the plan review stage.
The primary voltage of this customer owned xformer exceeds the 600v. range requiring GFPE. Additionally, this secondary of this xformer is not by definition a "Service". The voltage 480/277 and 1600a. puts it in the range of GFPE. Since the xformer is located about 50' from the building the xformer tap rules are complied with and we will be getting our overcurrent protection at the building in the form of a single disconnect and I'm saying that it is required to be GFPE. Am I correct??

[This message has been edited by George Little (edited 04-23-2006).]
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#97998 - 04/23/06 04:56 PM Re: GFPE/Feeder
winnie Offline
Member

Registered: 09/15/03
Posts: 652
Loc: boston, ma
215.10 for feeders.
230.95 for services.

215.10 refers to 230.95 and says that the specifications for feeder GFP are the same as service GFP. It specifically says that the GFP is required on the load side of the feeder unless it is provided at the supply side of the feeder.

I was not suggesting that GFP was required on the primary side of the transformer, nor was I suggesting that it was required prior to the disconnect in the building. I was simply suggesting a method that could be used to provide the secondary side GFP right at the transformer.

-Jon

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#97999 - 04/23/06 05:37 PM Re: GFPE/Feeder
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Sorry Jon, Thanks for the come back. I miss read your first comment.
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#98000 - 04/24/06 10:29 PM Re: GFPE/Feeder
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
I agree with "Winny" (Jon) on this one.

The Distribution Equipment being fed from this Tapped feeder will require a Main Disconnect / OCPD with GFPE - since the Main Disconnect / OCPD for this Gear is 1,000 Amps and larger, and the System is a Solidly Grounded Wye - exceeding 150 Volts to Ground, but not exceeding 600 Volts Line to Line.

Article 100 Definition of "Feeder" covers this type of Tapped Feeder; and the GFPE Requirements will include Tapped Feeders on Separately Derived Systems (AKA Customer Owned Transformers).

The Hazard of an uncontrollable Line to Ground Arc Fault is not limited to Systems derived solely, or directly, from Utility Transformers.
The Hazard (more correctly, the Potential for hazard) exists on any type System - be it SDS, Emergency Generation, Go-Generation, On-Site Generation, or Utility Derived.

If the Equipment from which the Tapped Feeders are derived from had GFPE, then this new Distribution Equipment would not require a Main Disconnect with GFPE - as the protection would already be in place.

In other words, if the Utility provided the Customer with a 4160Y/2400 3Ø 4 Wire System, and the Customer has a 4160V Delta x 480Y/277V 3Ø 4 Wire 2,500 KVA Transformer feeding a 4,000 Amp Section; and this Section had a GFPE Main Disconnect + the new Distribution Equipment you are installing was fed from this Equipment On The Load Side Of The GFPE Main Disconnect, then the new gear would not require a GFPE Main.

If the Secondary Feeders between the 2,500 KVA Transformer and the 4,000 Amp Gear were tapped, and this Feeder Tap is used to feed the newly installed Distribution Equipment, then the new gear requires a GFPE Main, because there is no Ground Fault Protection on the Line Side of the Main Disconnect for that Distribution Equipment.

Of course, there are the exceptions for Continuous Production Industrial setting and Fire Pumps, which removes the requirements of GFPE, but I think this installation does not fall into these two areas...???

Anyhow, just wanted to post this information for redundant reasons

Scott35
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Just Say NO To Green Eggs And Ham!

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#98001 - 04/25/06 02:06 PM Re: GFPE/Feeder
PCBelarge Offline
Member

Registered: 06/08/03
Posts: 657
Loc: Dobbs Ferry, NY, USA
The conductors off of the load side of the transformer are feeder/tap conductors.

Your installation sounds like it will require GFPE protection as per 215.10.

[This message has been edited by PCBelarge (edited 04-25-2006).]
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Pierre Belarge

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