Grounded Conductor as EGC

[mikehughes8]

I have a utility supplied transformer 3 phase / 4 wire here in Afghanistan that in addition to the grounded conductor an EGC is present and connected between the service disconnect and supply. Service disconnect is bonded.
I know this is a violation but I can't find an article that explicitly says this. I am leaning towards 250.4 (A)(5). Is this the best article to reference this violation.

Thanks

 

[nakulak]

250.30 A 1

however, if the transformer is utility owned, then this doesn't necessarily apply (ie if the service conductors are utility owned up to the disconnect, then the disconnect would still need a bonding jumper)

of course, all of this is assuming that the rules that apply are similar to stateside, and that the NEC even applies to the premise

 

[mikehughes8]

I thought 250.30 applied to separately derived systems. This is not. Transformer is utility owned.

250.142 states that on the supply side of the main disconnect the grounded conductor can be used for grounding equipment. Why then would I need a an EBJ. I have always thought this to be a violation and it seems to go against the intent of a "low impedance path" back to the source. I do not understand how ownership would play any role.

 

[radiopet]

Separately Derived System. A premises wiring system
whose power is derived from a source of electric energy or
equipment other than a service. Such systems have no direct
electrical connection, including a solidly connected
grounded circuit conductor, to supply conductors originating
in another system.

If the XFMR is utility owned then it is by NEC terms not a SDS and outside the scope of the NEC for the most part. Typically they would only bring in the supply ungrounded conductors and the grounded conductor and be done with it. If it was an SDS on the premise wiring then it would fall under the 250.30(A). If it was on the premise wiring system and we are dealing with the secondary then depending on the raceway used then 250.30(A)(2) could come into play if an equipment bonding jumper is needed.

So in some cases it is very important to know if we consider it an SDS and if it is utility owned then it is outside of the scope of the NEC. So I assume that is what Nak is eluding too. If their was an equipment bonding jumper run in your case and the utility provided it and without much detail I would connect it to the enclosure and isolate the grounded conductor busbar and treat it as such......but I would be very clear on what the utility is doing with that 4th conductor and how they are terminating it at the utility before I assumed it.

 

[Smart $]

I thought 250.30 applied to separately derived systems. This is not. Transformer is utility owned.

250.142 states that on the supply side of the main disconnect the grounded conductor can be used for grounding equipment. Why then would I need a an EBJ. I have always thought this to be a violation and it seems to go against the intent of a "low impedance path" back to the source. I do not understand how ownership would play any role.

You said it yourself, the grounded conductor "can be used"... but it does not have to be used. However, if an EBJ is used, it cannot be electrically connected to the grounded conductor at both ends... thus creating a parallel path for normal current and as a result two grounded conductors.

The preceding is a matter of code. As far as elementary electrical applications go, so what if there are two grounded conductors as long as they are insulated from or otherwise not exposed to personnel. The only difference here is the name tag assigned to the conductor.