SER

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Dennis Alwon

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It's not legal to run SEU or SER underground, regardless of whether it is in or not in a conduit. 338.12(A)(2). IMO, I don't understand why, or what the real life consequences of this are.


My understanding is that that water enters the conduit with all the mineral contents from the soil in it. It then seeps into the jacket and can eat away at the bare equipment grounding conductor.
 

iwire

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Massachusetts
My understanding is that that water enters the conduit with all the mineral contents from the soil in it. It then seeps into the jacket and can eat away at the bare equipment grounding conductor.

Is there any rule against pulling a bare AL EGC in an underground conduit?
 

Dennis Alwon

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Retired Electrical Contractor
Is there any rule against pulling a bare AL EGC in an underground conduit?
Probably a manufacturers rule but no NEC rule that I know about. I got my info from southwire. Bare aluminum cannot be within 18 inches of the ground for termination and I suspect there is a reason for that so logic would suggest to keep it out of a conduit in the ground. I would definitely check the manufacturer-- I bet it would be a NO NO

BTW, I never said it was an NEC rule :D
 

iwire

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Bare aluminum cannot be within 18 inches of the ground for termination

For GECs.

All I am saying is I don't understand the rule, I can use SER in wet locations. I can install bare AL EGCs in underground PVCs. But I cant put SER in an underground PVC.

I am not getting the logic used. :)


FWIW I am sure we will keep putting SER in PVC underground for temp feeders on construction sites. :cool:
 

Dennis Alwon

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Chapel Hill, NC
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Retired Electrical Contractor
For GECs.

All I am saying is I don't understand the rule, I can use SER in wet locations. I can install bare AL EGCs in underground PVCs. But I cant put SER in an underground PVC.

I am not getting the logic used. :)


FWIW I am sure we will keep putting SER in PVC underground for temp feeders on construction sites. :cool:


I am not certain you can install bare aluminum in a conduit underground per manufacturers instruction. If you can then there is no logic.
 

Carultch

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Location
Massachusetts
My understanding is that that water enters the conduit with all the mineral contents from the soil in it. It then seeps into the jacket and can eat away at the bare equipment grounding conductor.

Thanks for the clarification. Makes perfect sense.

Are you permitted to run a bare copper EGC in a conduit underground? If so, by combining the above reasoning, you should be able to run copper SEU or SER in a conduit underground. I know the NEC says otherwise though.
 
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