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#85590 - 07/18/03 04:50 PM Missing something?  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
A 600 240 volt 3phase service disconnect feeds a wireway that supplies several feeder disconnects.
One of the feeders supplies a wireway, with the conduit acting as EGC.
The wireway supplies 4 disconnects that feed 4 breaker panels via SER cable.
In each disconnect, the grounding conductor and neutral from the SER are connected together to the neutral lug, which is floating (not bonded).
All passed inspection.
What am I missing?


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#85591 - 07/19/03 08:10 AM Re: Missing something?  
PCBelarge  Offline
Member
Joined: Jun 2003
Posts: 681
Dobbs Ferry, NY, USA
Redsy
You did not miss a thing, the inspector and the contractor both missed something.
I am a Grounding and Bonding nut,and one of my friends loves to say "grounding and bonding are overrated". We both get a good laugh, seems the contractor and the AHJ also got a good laugh.

Pierre


Pierre Belarge

#85592 - 07/19/03 08:25 AM Re: Missing something?  
Tom  Offline
Member
Joined: Jan 2001
Posts: 1,044
Shinnston, WV USA
Take a look at 250.142 A & B. Also, 310.4, which will go away when you correct the connection between the grounding conductor & the grounded conductor.

Also, how are the disconnects grounded? If they are fed by SER cable, the needs to be a connection to the grounding conductor.


Few things are harder to put up with than the annoyance of a good example.

#85593 - 07/20/03 09:46 AM Re: Missing something?  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
Thanks,Guys.
Tom,
The disconnects are grounded via grounding locknuts. The voltage is 240, and no remaining KO rings exist, so that is sufficient. A grounding lug would have done the job correctly.
The thing that puzzles me is that, if the neutral & ground are isolated in the panelboards (I haven't looked yet), and the Neutral/Ground connection is floating in the disconnect enclosure, where is the parallel path for neutral current.
I will try to draw & post a diagram(eventually).

BTW,
This is in the basement of a restaurant.
Shouldn't SER cable should be prohibited?


#85594 - 07/21/03 08:02 AM Re: Missing something?  
Tom  Offline
Member
Joined: Jan 2001
Posts: 1,044
Shinnston, WV USA
If the neutral & the ground are connected to the same lug and or busbar at both ends, that is your parallel path.

There is nothing I know of in the NEC that would prohibit the use of SER cable in a restaurant, prior to the adoption of the 2002 NEC, and even then it would depend on the type of construction used and how the cable is installed. See 338.10(B)(4) and 334.10(3)


Few things are harder to put up with than the annoyance of a good example.

#85595 - 07/21/03 09:05 AM Re: Missing something?  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
Tom,

A restaurant would be considered a Place of Assembly (Article 518).
Wiring methods, generally, need to be Metal Raceways or MC cable (518.4 (A)).
I guess the basement ceiling/restaurant floor could be non-fire rated? (518.4 (B)).

[This message has been edited by Redsy (edited 07-21-2003).]



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