Cable Seal

[pitkas]

I Wired up a small above ground tank farm. Each tank has a level sensor that has a Belden 8441 cable (shielded twisted pair) ran inside rigid pipe with sealoffs. I failed an inspection because the cable can transmit gas inside the cable. Does anybody know of a kit that I can use to seal off the cable? Every parts house I called today did not have a clue what i was talking about.

 

[rbalex]

No listed product will accomplish what you want. Shielded twisted pair cables have several Exceptions, especially in Division 2.

 

[KentAT]

Does anybody know of a kit that I can use to seal off the cable? Every parts house I called today did not have a clue what i was talking about.

If an AHJ brings it up, I typically ask the AHJ what method they "approve" for sealing the cable ends, since the ball is in their court on this one. Typically ends up with silicone sealant.

501.15(D)(2) exception:
Exception: Multiconductor cables with a gas/vaportight
continuous sheath capable of transmitting gases or vapors
through the cable core shall be permitted to be considered
as a single conductor by sealing the cable in the conduit
within 450 mm (18 in.) of the enclosure and the cable end
within the enclosure by an approved means to minimize the
entrance of gases or vapors and prevent the propagation of
flame into the cable core, or by other approved methods.
For shielded cables and twisted pair cables, it shall not be
required to remove the shielding material or separate the
twisted pair.

kent

 

[hardworkingstiff]

I Wired up a small above ground tank farm. Each tank has a level sensor that has a Belden 8441 cable (shielded twisted pair) ran inside rigid pipe with sealoffs. I failed an inspection because the cable can transmit gas inside the cable. Does anybody know of a kit that I can use to seal off the cable? Every parts house I called today did not have a clue what i was talking about.

Out of curiousity, where was the job?

 

[rbalex]

IMO Kent’s suggestion is exactly right unless you are in a jurisdiction where approved ≡ listed or labeled. [The symbol “≡” means “identically equal”]. As I noted in my first response “There ain’t no such animal.” For the record though, also IMO, his suggestion should be correct in every jurisdiction.

In any cable with a “gas/vaportight continuous sheath capable of transmitting gases or vapors through the cable core,” the real issue is “…minimizing the entrance of gases or vapors and preventing propagation of flame into the cable core.” Note “minimize” the entrance and “prevent” the propagation of flame. Technically, the originating Division doesn’t matter.

ANY cable with a TC, PLTC, or ITC rating (along with any other it may have) has a “gas/vaportight continuous sheath” according to UL. (UL does not determine whether it is or isn’t “capable of transmitting gases or vapors through the cable core.”)

Therefore plugging up the end of the cable relatively well is all you should reasonably need to do.