Gasoline underground storage tank sump

[451F]

A contractor is asking:

1. Is watertight flexible metallic conduit permitted if it is equipped with seal-offs at each end and only contains intrinsically safe wiring? (I don't think the wiring should be used unless it is listed for the use as fumes can cross the seal-off inside of the sheath.)

2. Do pump (STP) conductors have to be in explosion rated flex AND jboxes? (YES)

Thanks for your opinions in advance.

 

[barbeer]

What exactly are you referring to a "sump" 514 is pretty specific in that only RGC, IMC, RNC and MI cable can be used.

Assuming that you are working with a 514 area of course......

 

[rbalex]

...
Assuming that you are working with a 514 area of course......

It sounds more like an Art 515 application to me; nevertheless, I concur with your general analysis.

I'm also going to ride my regular hobbyhorse - the location needs to be documented first [500.4(A)], then proper equipment and wiring methods can be selected fairly directly.

 

[kameele]

If it is indeed IS wiring, any unclassified wiring methods are allowed (504.20). Seals would be required for minimizing gas passage (504.70)

 

[rbalex]

Kevin,

While your statement is basically true, I tend to avoid references to Art 504, unless I already know IS is intended to be used. It raises certain inaccurate expectations.

"...any unclassified wiring method..." is somewhat misleading since Art 504 grounding/bonding [504.50&60] is still significantly more rigorous than most would normally expect. The additional requirements for control drawings [504.10(A)] is also something commonly overlooked.