disagree with inspector

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electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Occupation
Electrician
Ok well the title says it all, but i wanted to get some feed back here first since i generally assume i have overlooked something rather than the inspector being wrong. Single family residence, service entrance conductors enter a J/pull box and are tapped, to feed a 100A disconnect and a 200A service panel which are connected to the box with short runs of conduit, metal nipple to the 100A, pvc to 200A. I bolted a set screw terminal bar to the inside of the j-box, removing the paint under it first, and connected the three neutrals (feed and two taps) and the #2 grounding electrode conductor. To the same bar i also attached a bonding jumper to a bonding bushing on the rigid nipple that connects the j-box to the 100A disco. That is the layout and the inspecter cited two violations as follows:

"NEC 250.24 - an unspliced GEC shall land on the neutral buss in the service disconnect or disconnnects."

and

"NEC 250.6 - Parallel paths with the neutral conductor shall not be created."

Regarding thge first one, I see nothing in that section that states that i have to bring the GEC to the disconnects?

Regarding the parallel paths, he is referring to current being able to flow from from the neural buss in the 100A disco, thru the main bonding jumper (green screw), to the disco inclosure, thru the nipple, thru the j-box enclosure and/or bonding jumper, and to the neutral bar. I dont necessarily dispute that that is a parallel path, but what about exhibit 250.12 in the handbook, its the exact same thing? I know the handbook exhibits arent code but.....isn't this type of parallel path common in service equipment consisting of several enclosures? :confused:

Thanks in advance everyone
 
Re: disagree with inspector

A fault will always take the least resistive path to ground.

Anyone else want to chime in on this. Im learning here.
 
Re: disagree with inspector

any other way and how would you comply with
250.80 Service Raceways and Enclosures.
Metal enclosures and raceways for service conductors and equipment shall be grounded.
 
Re: disagree with inspector

With respect to the first quote from your inspector, ask him for the exact language, as written in the NEC 250.24 that says "only in the disconnect(s)". He should discover that it actually says
at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
Click to expand...
As for the second quote from your inspector, I would argue that the grounded service conductor is neither a grounding conductor nor a grounding path.
 
Re: disagree with inspector

A fault will take all paths availible,so they say.
electrofelon,On the first point the NEC is on your side all the way,on the 2nd point it's his to call.I really hate to say this but how hard is it to move the GEC to disconects?
It's not an unusual setup,you can see these where ever you go. Just by the way he worded it,I have the feeling he is stubborn.
Fig. 250.12 do you have a 2/0 neutral SEC,if so show him that for sure.

frank
 
Re: disagree with inspector

I dunno Frank,

To me, a metal conduit on the load side of the service disconnect is a grounding conductor.

On the line side of the service disconnect, the metal conduit containing the service conductors (120/240 V single phase) is part of the service grounded conductor. Using metal conduit as a raceway for the service entrance conductors cannot be prohibited, by Code. . .and if it is metal, it will share neutral current when both ends of the conduit connect to conductive equipment, enclosures, bodies, etc. that are bonded to the service grounded conductor.
 
Re: disagree with inspector

Al,

Elecrtofelon ran PVC to the 200a service panel,that would eliminate the path for neutral current? Yes/No

frank
 
Re: disagree with inspector

Frank,

You're right about the 200 A side, but, as I read
electrofelon posted April 07, 2005 10:54 PM
. . .metal nipple to the 100A. . .
Click to expand...
I take it that the inspector is calling the neutral current in the nipple as objectionable current in a grounding path.

In my opinion, he's mixing the terms.
 
Re: disagree with inspector

Thanks guys, I agree that it is impossible to eliminate all parallel paths when metal enclosures are involved, and that the inspector is making 250.24 more restrictive than it is. The homeowner is of the mindset that it is just easier to do what the inspector wants, and prefers that I do that. Thus I think I will play it safe and put the neutrals in a insulated splice block, run the GEC outside the J-box and tap off it to each disconnect per 250.64 (D). I will then bond the j-box and nipple to the neutral bus in disconnect. My only worry is that he would want the GEC taps to be exothermically welded or compressed to the GEC, and Idont have the capability to do either. The code does not say this has to be done at the GEC/GEC tap joint, just that the GEC itself must remain unspliced at these points. Right?
 
Re: disagree with inspector

250.24(A)(4) also explicitly allows ALL the grounding electrode conductors and equipment grounds to go to the equipment grounding bar and then to the neutral bar. This is standard practice in industrial services. This part was put in in 1981 because of the general requirement that you have two or more grounding electrodes in most cases. It also accomodates the problem that fusible disconnects and units breakers boxes do not have enough neutral terminals for all of the GECs and bonding jumpers such as for conduits. Also, because of the prohibition against 2 neutral wires or 1 neutral 1 EGC in the same terminal most service panels are REQUIED to have an equipment grounding bar.

Now, if that neutral bar in your J box is listed as an equipment grounding bar and not as a neutral bar, then you do have a violation. The neutrals would have to spliced independently of the ground bar using 2 or 3 split bolts with a bonding jumper running to the grounding bar.
 
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