501.10(B)(1) Terminated with Listed Fittings

[fifty60]

Regarding the requirement in NFPA 70 2017 501.10(B)(1) that type PLTC, TC, ect. cables must be terminated with listed fittings, is this regarding where the individual wires connect to the end device or is it the actual NPT fitting where the cable enters an enclosure? Would it be wherever the sheath on the cable is removed to reveal the final run of individual wires?

 

[petersonra]

Regarding the requirement in NFPA 70 2017 501.10(B)(1) that type PLTC, TC, ect. cables must be terminated with listed fittings, is this regarding where the individual wires connect to the end device or is it the actual NPT fitting where the cable enters an enclosure? Would it be wherever the sheath on the cable is removed to reveal the final run of individual wires?

Pretty sure they are referring to where it enters the box. It would not make much sense otherwise since there is no fitting anywhere else.

 

[fifty60]

That makes sense. Another related question. For example, PLTC cable, when the jacket is removed from the cable, is the exposed wiring inside the cable still PLTC rated? Or does the PLTC rating only apply to the cable with the jacketing and not the individual conductors?

 

[petersonra]

That makes sense. Another related question. For example, PLTC cable, when the jacket is removed from the cable, is the exposed wiring inside the cable still PLTC rated? Or does the PLTC rating only apply to the cable with the jacketing and not the individual conductors?

I don't see how it can be a PLTC cable if the jacket has been removed. They are just conductors at that point.

 

[fifty60]

For example, PLTC wire is acceptable wiring a Class I Div 2 location. I run my cable to my enclosure, which is also located in a Class I Div 2 location. I enter this enclosure through a listed fitting. Inside the enclosure, I will remove the jacketing on the PLTC cable, and the individual conductors will terminate at terminals on a PLC input card that is rated for Class I Div 2.

So I know the PLTC wire is acceptable, but what about the final foot of wiring in a class I div 2 location where I am inside the final enclosure and connecting the conductors to a device?

 

[petersonra]

For example, PLTC wire is acceptable wiring a Class I Div 2 location. I run my cable to my enclosure, which is also located in a Class I Div 2 location. I enter this enclosure through a listed fitting. Inside the enclosure, I will remove the jacketing on the PLTC cable, and the individual conductors will terminate at terminals on a PLC input card that is rated for Class I Div 2.

So I know the PLTC wire is acceptable, but what about the final foot of wiring in a class I div 2 location where I am inside the final enclosure and connecting the conductors to a device?

you are allowed to have THHN conductors in a C1D2 junction box. Why not the conductors from inside a cable?

 

[rbalex]

The conductors in PLTC cable aren't THHN - or any other 600V rated conductor. They are 300V, 105C.

That said, the NEC isn't a "design specification" and there is an expectation that a bit of common sense would apply. If the PLTC cables are otherwise acceptable in both Articles 500 and 725, then it is a reasonable expectation that they can be terminated in enclosures that are also acceptable in Article 500 with enough jacket removed to terminate the conductors.

 

[fifty60]

I am not able to find where THHN wiring is allowed inside a junction box in a CID2 location. I k now that 501.10(B)(4) says that boxes and fittings are not required to be explosion proof, but that does not seem to provide the justification of general purpose enclosures with THHN wiring..

 

[Jim1959]

I am not able to find where THHN wiring is allowed inside a junction box in a CID2 location. I k now that 501.10(B)(4) says that boxes and fittings are not required to be explosion proof, but that does not seem to provide the justification of general purpose enclosures with THHN wiring..

I believe any wiring type would be allowed inside an approved raceway or enclosure, the difference with PLTC or TC cable is that it can be installed exposed on a cable tray, therefore it has to be approved for the classification.

 

[fifty60]

Would the justification for this be 501.10(B)(1)(2) "Enclosed gasketed busways and enclosed gasketed wireways."?

 

[rbalex]

I am not able to find where THHN wiring is allowed inside a junction box in a CID2 location. I k now that 501.10(B)(4) says that boxes and fittings are not required to be explosion proof, but that does not seem to provide the justification of general purpose enclosures with THHN wiring..

Let’s take this from a different perspective. How do you know you can use THHN in any enclosure in an ordinary location?

 

[fifty60]

To clarify I am talking about a sub-panel enclosure on a piece of industrial equipment. Article 300 of NFPA 70 2017 explicitly states that "the provisions of this article are not intended to apply to the conductors that form an integral part of equipment...". So to justify the use of THHN or MTW wiring on my sub-panel, I know I would not be able to use NFPA 70.

So that would lead me to the normative standards. I know UL508 does not apply in hazardous areas, so I would turn to NFPA 79. 12.3.1 of NFPA 79 2007 (only edition I have handy) lists MTW and THHN as acceptable insulation types. So the normative standard NFPA 79 is how I would justify using THHN or MTW wiring on my sub panel in a non- hazardous area.

So how would I tie this back to being able to using THHN or MTW on a sub-panel within a Hoffman Enclosure in a CID2 area? Still not seeing it within Articles 500 or 501...

 

[fifty60]

501.10 is referencing "Wiring Methods" I am originally taking this to also include wire types themselves. But now I am starting to realize that wiring methods refers to actually running the wire/cabling from point A to Point B outside of an electrical enclosure. It is listing the types of conduits you can use, or it is listing the cable types you can use if you are not using one of the approved conduit types. It is not explicitly restricting the types of wiring you can use inside of enclosures.

501.20 is referring to Conductor Insulations in CID1 and CID2, and references situations where condensed vapors or liquids may collect on wiring. In that circumstance, the insulation shall be of a type identified for us under such conditions... This however, is not explicitly referring to inside of enclosures identified for CID2.

Since wire types are not explicitly referenced in 500 or 501 for CID2, I would base my reasoning for using MTW or THHN off of 500.8(A)(3) and 500.8(B)(1). Does this seem correct?

 

[rbalex]

I donno; sounds pretty flimsy to me. How do you know NFPA 79 is normative? It isn’t listed in NEC Annex A nor OHSA’s list of Appropriate Test Standards. Why should an AHJ buy in under Section 500.8(A)(3)? Since you now have taken it out of the NEC’s Scope, what has Section 500.8(B)(1) got to do with it anyway?

Since you appeared to want an explicit statement for THHN in Post #11, I was where you found such a statement for THHN for any Type of enclosure.

 

[fifty60]

Well I don't think there is anywhere that explicitly says you can use THHN or MTW inside a gp enclosure in a CID2 area. So would the reasoning then be that it is not explicitly prohibited? The wiring methods dictated by the standard would not apply once we are inside of the enclosure, so at that point, it would fall under the overall suitability of identified equipment criteria from 500.8.A...

 

[rbalex]

Well I don't think there is anywhere that explicitly says you can use THHN or MTW inside a gp enclosure in a CID2 area. So would the reasoning then be that it is not explicitly prohibited? The wiring methods dictated by the standard would not apply once we are inside of the enclosure, so at that point, it would fall under the overall suitability of identified equipment criteria from 500.8.A...

How would you know THHN or MTW is suitable in any Type enclosure in an ordinary location? It can be pieced together from several Sections, but it ain’t explicit anywhere else either.

 

[fifty60]

Would it be reasonable and acceptable to say that 501.10(B)(4) is saying that Boxes and Fittings that meet the requirements of 501.10(B)(4) are themselves accepted wiring methods? And that inside the enclosure you can use normal wiring practices just like in 501.10(B)(1) where you can imply that normal wiring practices can be used inside rigid metal conduit without threaded fittings?

 

[rbalex]

Would it be reasonable and acceptable to say that 501.10(B)(4) is saying that Boxes and Fittings that meet the requirements of 501.10(B)(4) are themselves accepted wiring methods? And that inside the enclosure you can use normal wiring practices just like in 501.10(B)(1) where you can imply that normal wiring practices can be used inside rigid metal conduit without threaded fittings?

Yes, Boxes and fittings fall under Section 501.10 Wiring methods.

 

[Wire-Smith]

wouldn't that kind of fall back to 110.2, AHJ approving the conductors? if nowhere is calling it out one way or another. it's probably not a wet location or any type of degrading atmosphere(uv) right (inside the enclosure).

 

[rbalex]

wouldn't that kind of fall back to 110.2, AHJ approving the conductors? if nowhere is calling it out one way or another. it's probably not a wet location or any type of degrading atmosphere(uv) right (inside the enclosure).

Sure, why not for those incapable of making cognitive leaps - let the AHJ tell you how to do everything.