EGC insulation rating for circuits <=1000V

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690David

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For a circuit whose current carrying conductors are required to have 1000V rated insulation, can this circuit's EGC insulation be rated less than 1000V? I have not been able to find a code requirement applying to EGCs regarding minimum insulation. The circuit may be in conduit or direct buried.
Thanks for any insights.

 
It's inferred...

250.118 Types of Equipment Grounding Conductors.
The equipment grounding conductor run with or enclosing
the circuit conductors shall be one or more or a combina-
tion of the following:

(1) A copper, aluminum, or copper-clad aluminum con-
ductor. This conductor shall be solid or stranded; in-
sulated, covered, or bare; and in the form of a wire or
a busbar of any shape.

(2) ...
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Yes, I agree, it is inferred. But is it required?
600V insulation is cheaper than 1000V and yields less conduit fill as well. Since the EGC could be bare, it seems 250 is not explicitly clear with regards to this insulation requirement.
I've argued this concern with the design engineer, making the case that less cost and an easier pull is more desirable.
Thanks again!
 
690David said:
Yes, I agree, it is inferred. But is it required?
600V insulation is cheaper than 1000V and yields less conduit fill as well. Since the EGC could be bare, it seems 250 is not explicitly clear with regards to this insulation requirement.
I've argued this concern with the design engineer, making the case that less cost and an easier pull is more desirable.
Thanks again!
Click to expand...
Actually, it is implied, not inferred. :)

The fact that the EGC is allowed to be bare wire implies that there is no requirement at all for insulation voltage!

Now if you do choose to put insulation on it, you might think that there would then a limit on the voltage of that insulation, but no such restriction appears in the NEC anywhere that I can see.
 
GoldDigger said:
Actually, it is implied, not inferred. :)

...
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No... it actually is inferred... :happyyes:

in?fer
in?f?r/
verb
Click to expand...


im?plied
im?pl?d/
adjective

  • suggested but not directly expressed; implicit.
Click to expand...
 
690David said:
Yes, I agree, it is inferred. But is it required?
600V insulation is cheaper than 1000V and yields less conduit fill as well. Since the EGC could be bare, it seems 250 is not explicitly clear with regards to this insulation requirement.
I've argued this concern with the design engineer, making the case that less cost and an easier pull is more desirable.
Thanks again!
Click to expand...
Hard enough getting some unclear issues clarified that seriously need it by the CMP's. Doubt you're going to get any clarification on an issue which is purposely vague.
 
Smart $ said:
No... it actually is inferred... :happyyes:
Click to expand...

Well yes and no...

It is implied by the language of the NEC that there is no insulation requirement.
It was inferred by you from that language that there is no insulation requirement.

From the context of ("....it is inferred...") and the accompanying quote from the NEC, I would have to say that it is more likely that implied is the better fit for your intended meaning.
On the other hand, if you meant to make a grammatically weird statement, then inferred is also just fine.
 
GoldDigger said:
Well yes and no...

It is implied by the language of the NEC that there is no insulation requirement.
It was inferred by you from that language that there is no insulation requirement.

From the context of ("....it is inferred...") and the accompanying quote from the NEC, I would have to say that it is more likely that implied is the better fit for your intended meaning.
On the other hand, if you meant to make a grammatically weird statement, then inferred is also just fine.
Click to expand...
Not yes and no. Simply yes, and not weird.

OP asked the question....
690David said:
For a circuit whose current carrying conductors are required to have 1000V rated insulation, can this circuit's EGC insulation be rated less than 1000V?
Click to expand...
The answer, "It is inferred..." by myself, another, or most all that read and can properly interpret the section quoted.

For example, I could have replied, "I infer yes from the following section."

You are correct, the Code text did the implying... but not I.
 
Smart $ said:
Not yes and no. Simply yes, and not weird.

OP asked the question....

The answer, "It is inferred..." by myself, another, or most all that read and can properly interpret the section quoted.

For example, I could have replied, "I infer yes from the following section."

You are correct, the Code text did the implying... but not I.
Click to expand...


So do I understand correctly? Simple yes or no.
"It is affirmative that you can use 600V insulation for your equipment grounding conductor, when routed with current-carrying conductors that have to have 1000V insulation."

There are two main reasons why I would insulate my EGC:
1. To reduce abrasion of the remaining wires, during the wire pull.
2. To reduce corrosion, when routed thru structures made from dissimilar metals that could cause corrosion. Aluminum, galvanized steel, etc.

I'm not concerned about debating the meaning of the words "inferred" and "implied".
 
Carultch said:
So do I understand correctly? Simple yes or no.
"It is affirmative that you can use 600V insulation for your equipment grounding conductor, when routed with current-carrying conductors that have to have 1000V insulation."
Click to expand...
Yes.
 
Carultch said:
...
There are two main reasons why I would insulate my EGC:
1. To reduce abrasion of the remaining wires, during the wire pull.
2. To reduce corrosion, when routed thru structures made from dissimilar metals that could cause corrosion. Aluminum, galvanized steel, etc.
...
Click to expand...
You can do anything you want to, that does not violate the code, in your design. So since the code does not require any specific insulation on the EGC, you are free to install any EGC you want to.
As far as bare, I often see that specified for non-metallic conduit runs. The idea is with a bare EGC, you should be able to clear a ground fault within the non-metallic raceway quicker than if you had installed an insulated EGC. Other than the non-metallic raceways, I don't think I have installed an bare EGCs.
 
don_resqcapt19 said:
You can do anything you want to, that does not violate the code, in your design. So since the code does not require any specific insulation on the EGC, you are free to install any EGC you want to.
As far as bare, I often see that specified for non-metallic conduit runs. The idea is with a bare EGC, you should be able to clear a ground fault within the non-metallic raceway quicker than if you had installed an insulated EGC. Other than the non-metallic raceways, I don't think I have installed an bare EGCs.
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Thank you all for the lively discussion; I feel clear on the difference between infer and imply! And I do believe we are in agreement that one may run an insulated EGC that has a voltage rating less than the current carrying conductors.

Since one main purpose of the EGC is to carry fault current, having the metal of the EGC as easy to get to as possible is desirable. I also would agree that metal raceways can be as effective as a bare EGC, perhaps better from a surface area perspective. But I want to add that a fault in a direct buried circuit (assume single conductors) without a bare EGC makes that fault very difficult to detect. This is why I prefer to run bare EGCs direct buried with the other single conductors.
 
RichB said:
LOL--I think the NEC "implied" it and then we as users "inferred" it!! :happyno::blink:
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I'm definitely inferring it. Nobody is forcing you to, though. :lol:

BTW, I believe a corollary to this discussion is that the EGC insulation does not need to be 'sunlight resistant' even if that's required of the other conductors. Etc. Etc.
 
electrofelon said:
If the conductor can be bare, then why on earth would an insulated EGC have to be of a certain voltage rating :?:
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I agree. I am not aware of any minimum insulation level requirement for grounding or grounded conductors on solidly grounded systems 1000 Volts and below. The only place I know that the NEC specifies a minimum insulation level for either is for the neutral conductor for systems over 1000 Volts in 250.84.

250.184 Solidly Grounded Neutral Systems
Solidly grounded neutral systems shall be permitted to be either
single point grounded or multigrounded neutral.
(A) Neutral Conductor.
(1) Insulation Level. The minimum insulation level for neutral
conductors of solidly grounded systems shall be 600 volts.

Exception No. 1: Bare copper conductors shall be permitted
to be used for the neutral conductor of the following:

(1) Service-entrance conductors
(2) Service laterals or underground service conductors
(3) Direct-buried portions of feeders

Exception No. 2: Bare conductors shall be permitted for the
neutral conductor of overhead portions installed outdoors.

Exception No. 3: The grounded neutral conductor shall be
permitted to be a bare conductor if isolated from phase conductors
and protected from physical damage.

I think it's just standard practice to use a 600 volt rated conductor when using an insulated EGC.
 
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jtinge said:
I agree. I am not aware of any minimum insulation level requirement for grounding or grounded conductors on solidly grounded systems 1000 Volts and below. The only place I know that the NEC specifies a minimum insulation level for either is for the neutral conductor for systems over 1000 Volts in 250.84.
...
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While not coming out and saying the grounded of a under 600 volt system has to be insulated, the requirement in 250.24, for the most part requires that the grounded conductor be insulated downstream of the service equipment.
 
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