I am inspecting a new service that consist of 600amp meter can with service conductors in parallel, that leads into a gutter and taps out to 4 main disconnects. The contractor bonded the metal gutter using only 1 of the grounded conductors in parallel (continous). So instead of coming out of the polaris tap that contains the grounded conductor in parallel and bonding the gutter, he landed it as mentioned above, would it be required that he land both the neutrals to the gutter since he used this method. I am thinking about 310.4B "be terminated in the same manner".

From your description I picture that the contractor skinned part of one of the grounding conductors and fed it through a lug (wire uncut) that was attached to the inside of the trough. I like your thinking, and I think I understand what you are asking. After looking through Articles 200, 230, and 250, I can find no code to accomplish what you seek.

Looking at 310 like you say, specific to parallel conductors, I am leaning toward agreeing with you. I think the intent of the code is that all parallel conductors be treated in exactly the same manner. That being said, bonding only one of them to the gutter (trough) may have some sort of weird effect given a fault condition -- although I don't know what. I also believe we are not all-knowing and there is no way we could know that.

So yes, you can use that code to have the contractor treat all the parallel service conductors in exactly the same manner. I don't necessarily believe that the conductor is being "terminated" at the trough, but it is being bonded to the trough, and thus grounding the trough itself. So the contractor should treat all of the parallel conductors in the same manner. Or -- run a single tail from the polaris tap and be done with it.

Good question. It is not everyday that someone makes me think. Anyone else agree or disagree? Please chime in.

Nick; I have to agree with you, both parallel conductors should be treated exactly the same

Agree

Maybe... Assuming the grounded conductor is superior in size to the minimum from table 250.66 for bonding, wouldn't a single bonding jumper be permitted? Assuming the parallelled grounded conductors are joined together within the meter base and in the trough I would think that any fault current would be safely transferred to the grounded conductors especially if the parallelled sets are within one raceway.
This is a lot of assumung and not a substitute for actually seeing the installation and making a judgement decision.

Agreed

I too agree with Ron. 250.92(b)(1) would permit the raceway or gutter to be bonded to the service neutral conductor, as long as it is sized per table 250.66 as Ron noted.

The problem here is not that the bonding jumper is of the right size, which it should be,using one conductor of the parallel Run, but is the termination of the parallel conductors on the polaris tap and to that point I would have to agree with Nick and Nova. Even though one conductor is terminated at the trough, it has bee extended in length also violating 310.4 (B)(1) and (5).I also agree with Ron in that it would not create any ground or fault current problems.

I don't understand how it is extended in length so it violates that code section?

By extending one conductor of the parallel set through the polaris to the ground lug makes it longer, does it not or are you considering it completed at the polaris as all other neutrals will tap off of there the length doesnt really matter. Either way its no big deal, I would have jumped off the polaris with the correct size bonding jumper but I guess he ran out of space. In some way or other this application seems to be in violatioin of 310.4 does it not??

Ok now I see the problem. Although the one neutral conductor is physically longer, because of the fact it is terminated into the polaris tap just like all the other neutral conductors, I don't think it is electrically longer where the impedance of the conductor would result in unbalanced distribution of tap load current between parallel sets, or any overheating effect.

Agreed but how about 310.4??

I think that since it terminates into the same polaris tap with all the rest of the neutral conductors you comply with the intent of 310.4(b)(1)&(5).

What do y'all think? Need more input!

I think first you need to decide if "terminate" means "to end" or to attach to a terminal. He he he. Told you it was a good question.

According to Websters Pocket Dictionary:
Terminate:
1. stop or end
2. form the end of

Here is my two cents. If we are going to use a parallel neutral to bond ahead of the main then it should be both. If we are bonding with one conductor from the main it's 250.66 and the 12 1/2 rule. If we run a conductor in each conduit from the main it should be sized per 250.66 based on size of conductor in each raceway.

I have a few of questions?

1) Where does the GEC originate (meter/gutter/other)?
2) What size are the ungrounded conductors?
3) What size are the grounded conductors?
4) Is the grounded conductor attached to the gutter ahead or behind the polaris block?

Back in the day before the polaris blocks were available, I would have bolted an un-insulated utilco bar to the gutter, terminated both grounded conductors in that bar and called it a day.

IMHO
Neal Burdick
City of Tampa
Construction Inspector II

I'm still wondering if my mental picture of the installation is correct? Otherwise the entire thread is a moot point! Maybe Nova can chime in and let us know.

??

In re-reading the original post, It sounds like one of the parallel conductors is terminated to the gutter and the other one is terminated in a Polaris bar, I think RED TAG

I think this is what they are talking about

Nick, the installation is exactly like you mentioned in your first post. I attended a 2011 code seminar in fort lauderdale last saturday and ask John Minick from NEMA this question and he gave me the same response you posted first. The drawing submitted by Paul is not the installation, the contractor skinned the parallel conductor before reaching the polaris tap (only one conductor).

Val Perez
City of Pembroke Pines Fl.
Electrical Inspector/Plans Examiner

I have just been watching this show and I agree it is probably a technical violation but I do not see the hazard.

After re reading Nick's first post, I see my mistake in the diagram but still agree with Nick.

I was using a lay-in lug bolted to the cabinet. Rule of thumb being the fewer conductors and connections the better.

This was an excellent question.

Electrically I have a hard time arguing with the simplicity of your installation but I agree the language of the code probably does not support it.

I too now agree with Nick.

My first understanding was that the neutral first terminated into the polaris tap, than to bonded to the gutter. I would not have a problem with that, since it terminated with the other parallel neutral conductors at the same point.

But with the new understanding, terminating to a lug bonded to the gutter first, than the polaris tap with the other neutrals I would not approve.

Thanks for the clarification.