1000V systems and voltage rating of EGC wire

Carultch

Senior Member
Location
Massachusetts
When you install 1000V PV systems, obviously the current-carrying wires have to have insulation rated at 1000V or greater.

What about the equipment grounding conductor? Is there any rule requiring an insulated EGC to have the 1000V rating? Given that an EGC can be bare wire, for which voltage rating isn't applicable, can an EGC still have a 600V rating in a 1000V system?
 

Carultch

Senior Member
Location
Massachusetts
I dont see any issue. I could see there being an EGC insulation rating required if the EGC was required to be insulated, such as for a pool installation, but in general no.
That's my thought too. Physically, there shouldn't be an issue. I believe that if EGC can be bare, it should be able to be anything. The main reasons why I specify insulation are to reduce abrasion during pull and to avoid corrosion conflicts of copper-on-conduit.

But is there any passage in the NEC that might unintentionally require 1000V ground wire?
 

69gp

Senior Member
Location
MA
When you install 1000V PV systems, obviously the current-carrying wires have to have insulation rated at 1000V or greater.

What about the equipment grounding conductor? Is there any rule requiring an insulated EGC to have the 1000V rating? Given that an EGC can be bare wire, for which voltage rating isn't applicable, can an EGC still have a 600V rating in a 1000V system?

I would run the bare wire. Even though we know its just the EGC the wire is marked for 600 volts only. I have seen it flagged before.
 

jaggedben

Senior Member
This reminds me of inspectors who have a problem with using a solid THWN-2 ground on an array, because the insulation is not rated to be outdoors. :slaphead:
 

iwire

Moderator
Staff member
Location
Massachusetts
Relevant.

300.3(C) Conductors of Different Systems.

(1) 600 Volts, Nominal, or Less. Conductors of ac and dc circuits, rated 600 volts, nominal, or less, shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.

Exception: For solar photovoltaic systems in accordance with 690.4(B).
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
I agree with you that they are not circuit conductors.

However the section says all conductors in the second sentence.

Is the second sentence stand alone? I do not know.
You make a good point, but I don't see the second sentence as "stand alone".

I see the governing rule as being 250.118(1).
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I agree with you that they are not circuit conductors.


However the section says all conductors in the second sentence.

Is the second sentence stand alone? I do not know.
IMO the "all conductors" in the second sentence is limited by the "conductors of ac and dc circuits" in the first. That excludes the EGC, which is no more a circuit conductor than is the conduit the wires are in.
 

iwire

Moderator
Staff member
Location
Massachusetts
IMO the "all conductors" in the second sentence is limited by the "conductors of ac and dc circuits" in the first. That excludes the EGC, which is no more a circuit conductor than is the conduit the wires are in.
I agree that makes sense, I just don't think it is really worded that way.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I agree that makes sense, I just don't think it is really worded that way.
The NEC is full of badly worded, ambiguous, and even contradictory language, but I think this one is relatively clear. If you take "all conductors" to mean literally ALL conductors, that could mean the MV conductors on the poles outside. In this case the interpretation I have is supported by the facts that the EGC could be bare wire and that the conduit enclosing the conductors usually functions as a parallel EGC.

All joking aside, one does have to use a bit of common sense when interpreting the NEC.
 

iwire

Moderator
Staff member
Location
Massachusetts
If you take "all conductors" to mean literally ALL conductors, that could mean the MV conductors on the poles outside.
Now you are just being silly.:D

Ii could very well mean all the conductors in the raceway and I am still not convinced that is not what it means.


Not something I have to worry about. :cool:
 
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