Insulation type for typical grounding conductors?

Isaiah

Senior Member
Does anyone out there know what kind of insulation is used for a typical green, insulated grounding conductor the kind that forms a buried ground loop, such as #4/0 or #2/0? The specification I am looking at calls for XHHW-2 insulation; but this seems like overkill for a simple, single conductor copper grounding conductor intended soley for bonding metal structures, likely to become energized.
thanks in advance.
Isaiah
 

infinity

Moderator
Staff member
I'm confused with the terminology is this a ground ring electrode outlined in 250.52(A)(4)?
 

ron

Senior Member
A Ufer ground can't use buried insulated conductor. The conductor needs to be in contact with the earth.
 

charlie b

Moderator
Staff member
You are talking about two completely separate concepts.
. . . the kind that forms a buried ground loop, such as #4/0 or #2/0?
Here you are talking about the "grounding electrode system." This uses grounding electrodes, such as ground rods or (from your description) ground rings. This requires metal to be in contact with dirt. Any insulation would make the "in contact with dirt" impossible. That is why others have said this wire must be bare copper.
. . . a simple, single conductor copper grounding conductor intended soley for bonding metal structures, likely to become energized.
Here you are talking about bonding conductors, used to connect metal to metal, and not to dirt. It would be internal to the building, and not buried in the ground. Someone will have to check me on this, but I believe these conductors also do not need any insulation system.
 

PaulMmn

Senior Member
Is there anything about bonding from the main panel to the gas or water piping, running inside, required to be 'green?'
 

Isaiah

Senior Member
You are talking about two completely separate concepts. Here you are talking about the "grounding electrode system." This uses grounding electrodes, such as ground rods or (from your description) ground rings. This requires metal to be in contact with dirt. Any insulation would make the "in contact with dirt" impossible. That is why others have said this wire must be bare copper.
Here you are talking about bonding conductors, used to connect metal to metal, and not to dirt. It would be internal to the building, and not buried in the ground. Someone will have to check me on this, but I believe these conductors also do not need any insulation system.
I should clarify: The insulated #4/0 is not really intended to be an electrode, i.e. Ground Ring in the truest sense per 250.52(A)(4).Its really a very large, intricate bonding jumper used to connect grounding electrodes such as ground rods etc installed plant wide. Its also buried only 18" instead of 30". The 'taps' from the #4/0, are #2/0 and #2 insulated. I was simply inquiring as to what was the typical insulation type, such as XHHW-2, THHN/THWN etc, utilized for these conductors.
I do however agree, the system would be more effective overall if the conductors were bare instead of insulated - but that is not what the client wants.
 

infinity

Moderator
Staff member
I should clarify: The insulated #4/0 is not really intended to be an electrode, i.e. Ground Ring in the truest sense per 250.52(A)(4).Its really a very large, intricate bonding jumper used to connect grounding electrodes such as ground rods etc installed plant wide. Its also buried only 18" instead of 30". The 'taps' from the #4/0, are #2/0 and #2 insulated. I was simply inquiring as to what was the typical insulation type, such as XHHW-2, THHN/THWN etc, utilized for these conductors.
I do however agree, the system would be more effective overall if the conductors were bare instead of insulated - but that is not what the client wants.
Thanks for the clarification, since the conductor can be bare and is not required to be insulated I would use whatever insulation type is cheapest. If this conductor qualifies as a GEC it is not required to be buried 18" deep that would be a design issue.
 

Isaiah

Senior Member
Thanks for the clarification, since the conductor can be bare and is not required to be insulated I would use whatever insulation type is cheapest. If this conductor qualifies as a GEC it is not required to be buried 18" deep that would be a design issue.
Yes, exactly my thoughts, why use XHHW-2 for this application?
 

ron

Senior Member
Yes, exactly my thoughts, why use XHHW-2 for this application?
Depending on where you are getting the direction to use XHHW-2, it may be to reduce unintentional contact with earth to reduce circulating currents or some other perceived reason. XHHW-2 is pretty tough / robust and maybe they want it to resist penetration from backfill or other debris.
 

Isaiah

Senior Member
Depending on where you are getting the direction to use XHHW-2, it may be to reduce unintentional contact with earth to reduce circulating currents or some other perceived reason. XHHW-2 is pretty tough / robust and maybe they want it to resist penetration from backfill or other debris.
This is coming from one of the Client standard details, I believe your last statement "XHHW-2 is pretty tough / robust and maybe they want it to resist penetration from backfill or other debris" is the most probable reasoning.
 

K8MHZ

Senior Member
This is coming from one of the Client standard details, I believe your last statement "XHHW-2 is pretty tough / robust and maybe they want it to resist penetration from backfill or other debris" is the most probable reasoning.
I have yet to see plastic insulation that is tougher than the copper conductor it is insulating.
 
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