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?
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.
Re: Missing something?#85592 07/19/0307:25 AM07/19/0307:25 AM
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?
Re: Missing something?#85594 07/21/0307:02 AM07/21/0307:02 AM
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.
Re: Missing something?#85595 07/21/0308:05 AM07/21/0308:05 AM
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).]