Classified Area-Empty Conduits-- Sealoff Requirements

[BLarsen1964]

I have a classified Area-- (Class 1-Div 1). Underground conduits from an MCC (outside the classified area) to a future equipment location. These will remain empty for a later date--possibly years. Is it necessary to use a sealoff or is a malleable iron threaded plug in the GRC coupling at the floor on each end acceptable?

 

[don_resqcapt19]

For that purpose, I have always used a plumbing pipe cap, and not a plug in a coupling. However I am not aware of any specific requirement.

 

[tom baker]

A plumbing pipe cap will seal better as it has tapered threads, an electrical coupling does not.

 

[synchro]

A plumbing pipe cap will seal better as it has tapered threads, an electrical coupling does not.

They use NPT threaded pipe caps for natural gas, and so it should be adequate for these purposes.

 

[petersonra]

They use NPT threaded pipe caps for natural gas, and so it should be adequate for these purposes.

It should be but does it meet the NEC requirements as a seal?

In any case, the plumbing fitting is not listed for this use and the code requires listing.

I would look closely at what 501.15 actually says.

 

[don_resqcapt19]

It should be but does it meet the NEC requirements as a seal?

In any case, the plumbing fitting is not listed for this use and the code requires listing.

I would look closely at what 501.15 actually says.

Listed or not, I will take a plumbing cap over a conduit coupling and plug every time.