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#80097 - 02/27/02 07:23 AM Isolated neutral bus bar
beach Offline
Member

Registered: 02/12/02
Posts: 26
I had an inspector argue that the nuetral should be isolated but in this situation I believe he was wrong.

3 wire sub fed from 60 amp ocpd from main panel.
Detached garage. Garage has ufer.
Can someone shout out some code.

Thanx,
Jon

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#80098 - 02/27/02 08:32 AM Re: Isolated neutral bus bar
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
I think 4 wires are preferrable, but--
What is the raceway material?
Look at 250.32(B)(2).
Also see 250.32(D).

[This message has been edited by Redsy (edited 02-27-2002).]

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#80099 - 02/27/02 07:07 PM Re: Isolated neutral bus bar
beach Offline
Member

Registered: 02/12/02
Posts: 26
Raceway material is carlon. 4-wire is niether preferred or needed, the garage has a ufer ground.

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#80100 - 02/28/02 04:58 AM Re: Isolated neutral bus bar
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
Are there any other conducotive paths between the 2 buildings?
Don(resqcapt19)
_________________________
Don(resqcapt19)

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#80101 - 02/28/02 06:36 AM Re: Isolated neutral bus bar
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
250.32(B)(2) seems to justify your installation.

Carflex? Is it buried?



[This message has been edited by Redsy (edited 02-28-2002).]

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#80102 - 02/28/02 07:37 AM Re: Isolated neutral bus bar
beach Offline
Member

Registered: 02/12/02
Posts: 26
Don,
No conductive path to the main building that would create a dangerous parallel current path for the line to neutral circuit.
That I why I believe I am correct.

Also this is a all-in-wonder inspector.

Redsy,
No not carflex, carlon schedule 40. Burried at 18" of cover.

Thanks,
Jon

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#80103 - 02/28/02 08:18 AM Re: Isolated neutral bus bar
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
If there are only three conductors it becomes very dangerous to isolate the grounded conductor. If the grounded conductor is isolated and there is not an EGC there is no fault clearing path.
Don(resqcapt19)
_________________________
Don(resqcapt19)

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#80104 - 02/28/02 10:17 AM Re: Isolated neutral bus bar
motor-T Offline
Member

Registered: 11/10/01
Posts: 293
Loc: Girard, Ohio, USA
You keep insisting that you have a Ufer ground, this is better than a ground rod but still not good enough to trip a breaker, the grounded(neutral) conductor is used for fault tripping.
If there is no parallel ground paths common to both buildings, then you should be able to run a 3 conductor out there; however if the AHJ wants a 4-condutor, then he will contiinue to gig you until you convince him otherwise.
I personally find it prudent to say ok and do it the way he wants afterall he is the Authority Having Jurisdiction.
-Mark

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#80105 - 02/28/02 11:34 AM Re: Isolated neutral bus bar
beach Offline
Member

Registered: 02/12/02
Posts: 26
The wire is already run (3 wire). The inspector does not have a problem with it being 3-wire, his only gig was with the neutral bar being bonded to the ges. I don't want to " say ok and do it the way he wants afterall he is the Authority Having Jurisdiction" because I know this would be a dangerous situation as Don has also pointed out.


250.32 (B)(2)
Clearly defines that I was correct.

My installation fits the 3 criteria.

1. No equipment grounding conductor is run with the supply to the building. (3 wire)
2. There are no continuous metallic paths bonded to the ges in both buildings.
3. There is no ground-fault protection installed on the common ac service.

Under these conditions nec states
" the grounded circut conductor (neutral) run with the supply to the building or structure SHALL be connected to the building or structure disconnecting means and to the grounding electrode(s) and shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded." NEC 2002

I will bring my code book to the re-inspection and have him read it himself. I can't see how he could interpit it any different.

Than you again for you input.

Jon

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#80106 - 02/28/02 01:52 PM Re: Isolated neutral bus bar
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
Jon,
Do not under any conditions allow that panel to be energized without bonding the grounded conductor to the equipment grounding conductors and grounding electrode conductor in the second building. Without this bond there is no fault clearing path and all conductive itmes conected to the electrical system would become hot if there was a ground fault. There is no way to clear this ground fault without the bond. This would be a very very dangerous installation if the bond is omitted. If you are a contractor, you are still subject to law suits if someone got hurt or killed even if the inspector told you not to bond the neutral.
Don(resqcapt19)
_________________________
Don(resqcapt19)

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