My friend recently asked me to help him with his outside sign, which was ON all of the time. The contractor merely forgot to tie in the circuit to the timer but, while I was tracing out the wiring, I noticed the Electrical Contractor, which installed the wiring in his new store, pulled individual neutrals with each circuit, a good thing! The other thing I noticed was that he decided to tie all of theses neutrals together? I know this is not a good practice for many reasons but I would like to know the code, if there is one that prevents this? I only had the opportunity to check four junction boxes and all were the same. Multiple conductors with individual neutrals tied together, I’m not as concerned with two conductors and two neutrals tied together, even though it might confuse the next electrician who tries to work on the store, the contractor might just say he was doubling the neutral size like so many do for computer heavy applications. I’m concerned he might have done the same for three or more circuits and since the store is a Laundry Mat with a lot of electronics. There might be a chance that when and if someone works on these circuits live, he may damage some of the electronics inside the store. Has Cook County implemented neutral tracers for individual circuits? In the two circuit two neutral scenario should the two neutral wires be identified as one in the panel and or at all junction boxes for safety?
I would have a problem with any installation that parallels neutrals at thebranch circuit level. I agree that this configuration is a fertile opportunity to create feed back and cause injury due to shock or electrocution. The reason why roof vent units generally have switches that break the grounded conductor as well as the ungrounded conductor is precisely to prevent such accidents. This configuration also defeats UL standards for panel boards, which require each neutral terminate at an individual lug. This allows a service person the ability to completely isolate a circuit during maintenance and prevent a back feed so to say. Don’t forget whenever a circuit is de-energized if a common neutral is connected to the other side a potential to ground may be present. I don’t have the number for the UL standard right now but if it’s important I can get it in the morning. Another UL standard (I think UL 66) requires that the equipment grounding conductor connection be maintained when equipment is serviced. These two standards where the substantiation for the new language in article 408.21 of the 2002 NEC. These requirements have been included in the booklets shipped with panel boards for quite some time. Article 300.4 generally rejects paralleled conductors smaller than 1/0.
Re: Multiple Neutrals Not Seperated Chicago Code / NEC#88811 07/29/0409:28 PM07/29/0409:28 PM
Guys, Thanks for the input, I would have looked it up myself but I recently borrowed my codebook to someone else and it has not been returned yet. I probably should have kept my old ones. I'm interested in the information regarding the UL a standard that “cpal” refers to, if it is not too much trouble. I will copy this thread and give it to my friend so he fully understands what I am talking about. I'd like to report the job to the electrical inspector who should have caught this problem ahead of me but I don't want my friends store shut down. My biggest concern is, how many jobs has this contractor done like this, it's my understanding he is basically a one man shop and is there someone I can call who might be able to point him in the proper direction.
Re: Multiple Neutrals Not Seperated Chicago Code / NEC#88812 07/30/0412:53 PM07/30/0412:53 PM
This article is documented in the 2001 ROP Purposal 9-113 on page 674. It references UL Standard 896A for service equipment. The other standard is UL 67 for panelboards it addressed the connections of equipment grounding conductors, but appears to have been deleted as of Sept. 20 of 2002.
The issue of parraleling the grounded circuit conductor is not necessarily one that the NEC will address directly. Ultimately the condition you describe is a practical application. Granted one that most professionals would consider unorthodox. If you reference Article 90.1 Purpose, and specifically 90.1 (C), Intention, which states, “This Code is not intended as a design specification or an instruction manual for untrained persons”, you can see how the document handles unforeseen contingencies. Maybe the Code could use direct language to prevent such an installation but beyond 310.4 and 408.21 the Code is reluctant to dictate circuitry.