501.15(D) (1) exception

[nhee2]

I see a number of posts regarding how this exception applies to shielded /multiconductor cables - and that removal of shielding material or separation of conductors is not required provided the termination of the cable is sealed by an approved means.

I have not seen any recommendations or links to 'approved means' of sealing a cable at the termination.

Does anyone have a link or example of the sealing means that would be used to satisfy 501.15(D)(1) (or 501.15(D)(2)) exceptions?

Thanks.

 

[greenspark1]

These glands look like they would work, many are Class I rated:
http://www.cooperindustries.com/con...es/cable_glands_-_northamericanstandards.html

You'd have to match the gland to the type of cable you're using. I'm actually looking for one for liquidtight and not seeing one, hmmmmm.

 

[rbalex]

I see a number of posts regarding how this exception applies to shielded /multiconductor cables - and that removal of shielding material or separation of conductors is not required provided the termination of the cable is sealed by an approved means.

I have not seen any recommendations or links to 'approved means' of sealing a cable at the termination.

Does anyone have a link or example of the sealing means that would be used to satisfy 501.15(D)(1) (or 501.15(D)(2)) exceptions?

Thanks.

We are looking at several possible conditions but the solutions overlap a bit.

In Division 1, the shielded /multiconductor cables could be cable in raceway or a Type MC-HL cable. Type MC-HL can be rather direct; a Type TMCX connector with an integral sealing compound is suitable as both an entry cable gland and sealing fitting. The individual pair shields don't require removal/separation. This is not the only method, but it is the least "painful". The other method is essentially the same as a cable in raceway.

For a cable in raceway a "standard" raceway seal is suitable. BUT the outer jacket, if any, must be peeled back to where "... the sealing compound surrounds each individual insulated conductor in such a manner as to minimize the passage of gases and vapors." While the individual pair shields don't require removal/separation, THIS IS STILL A VERY PAINFUL PROCESS.

 

[rbalex]

...

I'm actually looking for one for liquidtight and not seeing one, hmmmmm.

That's because LFMC isn't suitable for Division 1.

 

[nhee2]

Thanks for the feedback.

So it looks like unless I am running a cable which is rated for Class I-Div 1 (such as MC-HL, which I would not run in conduit), then I am required to remove the jacket.

I am not sure what the exception in 501.15(D)(2) is allowing me to do then. For instance if I am running a twisted shielded pair to a transmitter, and the cable jacket is vaportight, then the exception allows me to seal the cable end in the enclosure with an approved method. Some previous posts referenced products by 3M or others, but I am not familiar with them.

I agree that removing the jacket at a conduit seal is painful.

 

[rbalex]

I've spent half the morning trying to recover an old diagram I created when we discussed this topic years ago. I can't find nor recreate it at the moment. I'll do my best to describe it later. I'll assume the multi-conductor cable is effectively a Type TC, although it would basically apply to any multi-conductor cable with a gas/vaportight continuous sheath that is both acceptable in raceway and part of a recognized wiring method in Division 1.

Since we are talking about cables in conduit in Division 1, Section 501.15(D)(2) Exception tells us we can consider a jacketed cable as a single-conductor with respect to passing through the seal.

NOTE: UL does certify that all listed Type TC cables have a gas/vaportight continuous sheath, but makes no declaration about its ability to transmit gases through the core or not. You may as well assume it can.
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Also note Section 501.15(D) makes NO mention of boundary seals; that is covered in Section 501.15(A)(4), but you still consider the multi-conductor as a single-conductor at the boundary.

Assume the cable passes intact entirely through the seal. That leaves the ends of the cable open and a potential entry point for gasses and vapors. Several manufactures make adhesive lined heat shrink tubing that seal the ends nicely - especially for small instrument conductors.

It is important to recognize that approved does not necessarily mean listed or labeled. It simply means "Acceptable to the authority having jurisdiction." Of course, depending on the jurisdiction, it may still mean listed or labeled.

 

[nhee2]

Thanks, the link clears things up for me. I was thinking the 'sealing' method was something more complex. I understand that ultimately the AHJ would determine what is 'approved'.

If removing the cable jacket within the conduit seal was the selected method of installation, then the cable jacket removal within the seal would only be required at the end of the cable run, where the cable is being broken out in the end device, assuming the cable type includes a gas/vaportight jacket. In other locations (boundary seals) the cable is treated as a single conductor.

I have been out of this 'game' for several years and just getting back into haz. location installations. This forum is a great resource. Thanks.