Re: sealing multi-conductor I/S cables
Lou,
In my opinion, ultimately it would pass. There are a lot of ?howevers.?
I?m using the 2005 NEC.
First, a careful reading of 501.10(A) does NOT directly permit intrinsically safe wiring methods in Division 1; in fact, there is no reference to Art 504 or intrinsically safe circuits in mandatory text in Art 501 at all. You have to ?fudge? it in by inference from the general ?Scope? statement in 500.1 which says: ?Articles 500 through 504 cover the requirements for electrical and electronic equipment and wiring for all voltages in Class I, Divisions 1 and 2?? [Bold Italics mine]
Art 504 also ?self-declares? its applicability to Division 1 in 504.20, which then re-introduces sealing requirements of 501.15 via 504.70.
Now that I?m comfortable with using IS (with PVC) in Division 1, lets look at the seals.
The FPN No. 1 to 501.15 states: Seals are provided in conduit and cable systems to minimize the passage of gases and vapors and prevent the passage of flames from one portion of the electrical installation to another through the conduit.
If we assert that there will be no flames to prevent (no ignition source), then we only need to deal with minimizing the passage of gases and vapors and ?ductseal? should do just fine.
BTW this is why I don?t like the new 501.15(C) Exception. In an IS application there is no way to ignite vapors that may possibly get into the raceway; however a fault in the conductors of other types of circuits could. The theory the Proposal that the Exception was based on stated the boundary seals were only necessary to prevent gas migrations. My contention is if you think there are gases to migrate at all you also need to be concerned that they may get ignited, in which case the seal should be XP.