517.13 and underground conduits

[DAL]

We are wiring a dental office. Specifically, the underground to the chair's quad receptacle (located under the chair) is normally run with PVC under the concrete with (4) #12s (hot,neutral & 2 grounds). The inspector required steel conduit because one of the grounds had to be the conduit. How is this diffrent then 12-2 mc hg with its cu. wire and alu. wire?

 

[LarryFine]

How is this diffrent then 12-2 mc hg with its cu. wire and alu. wire?

Becuase the aluminum wire is the metallic sheath's spirals shorting conductor, and you don't even need to terminate it.

 

[roger]

How is this diffrent then 12-2 mc hg with its cu. wire and alu. wire?

Because two copper wire conductors do not meet the requirement of 517.13(A). The AL runner in the HCFC is only to assure continuity of the metalic sheath.

Roger

 

[jbelectric777]

so people in the dental chair stay calm:grin:

 

[jbelectric777]

j/k sorry:grin: