Fueling station sealing question

[Dr Duke]

I will try to make this as simple as I can. This is pertaining to intrinsically safe circuits. Where the conduit comes from the building, into the probe pit, out of the probe pit, into the submersible pit. If I have intrinsically safe circuits coming from the building, I obviously need my boundary seals on both ends (building and probe pit).

My question is, is a seal required for the conduit entering the submersible pit, or the conduit coming from the probe box to the submersible pit? The pit contains a power conduit, a spare conduit, and the mentioned intrinsically safe conduit.

Thank you

 

[rbalex]

I've hesitated answering this because I don't like the answer and it is one of the reasons I'm not a big fan of intrinsically safe systems (IS). They can be misleading in the literal text.

There are multiple relevant Sections. Begin with 504.70 which deals with sealing in intrinsically safe systems. It cross references to Section 501.15 with reference to your description. Section 514.3 addresses classifying locations. Section 514.9 also mentions the "pit" as a "cavity" in direct communication with a/the dispenser.

Section 514.3 defines the pit as Division 1. Consistent with that, Section 514.9(A) would require sealing raceways entering or leaving the pit, IS or not. Where it become complicated in my opinion is, while Section 504.70 would also require seals, they would not be required to be explosionproof. If IS were the only consideration, I would probably clinch my teeth and let it ride. But you mentioned there was non-IS (power) involved as well. Now while Section 504.30 does require IS to be separated from non-IS systems, it doesn't necessarily require that separation to be explosionproof. (A properly installed power system probably would be.)

Add to the mix Section 504.60 which still essentially requires bonding to be consistent with Section 501.30 because potential circulating currents generated by non-IS wiring could still cause an arc, in which case IS wouldn't do much good.

Taken as a whole, since seals are required in any case, I would use explosionproof seals in the pit as you have described the installation for both IS and non-IS wiring methods.