Damamged THHN

Status
Not open for further replies.
weressl said:
So then why is the thread title: Damamged THHN ?
Click to expand...

Sometimes you have to read, or even re-read an entire thread to see what stops the bus made...lot of people get on and off at various stops - sometimes the driver even deviates from the course...sometimes it's like a "chinese fire-drill" :smile:
 
weressl said:
So then why is the thread title: Damamged THHN ?
Click to expand...

Ok, let me see if I can help by reposting Dave's comments stopping at where it changed to NM cable.

When Gil visited us previously, he made a splash by noting that the transparent nylon covering THHN/THWN, while arguably making them sexy compared to THW, is not required to maintain the conductor's dielectric properties. Therefore, if in the course of installation the nylon suffers the odd nick, or unsightly run, or even is scraped off, the conductor is fine so long as the insulation underneath remains intact. Learning this much, we had to have Dave over for more of the story.

Unless conductors are exposed to gasoline or oil, or submerged for an extended period we're talking many months--the nylon covering offers strictly a mechanical protection, Dave explained, with the underlying PVC supplying the dielectric properties as Gil had told us. The nylon actually is stripped away for the UL acceptance test. Therefore, if the nylon is scraped off, but the plastic underneath is intact, an appropriate response usually is "Good; it's done its job," and a green tag.

It's not just the nylon covering on THHN/THWN, we learned, but the sheaths on cable assemblies also often are optional.
Click to expand...


At this point it shifted to damaged NM cable sheaths.

Roger
 
roger said:
Laszlo, if you go back and read post #8 you will see that where the discussion of repairing a cable sheath comes into play, it is addressing NM cable, not the nylon jacket of THHN/THWN.

Roger
Click to expand...

Copy of post #8 of the original thread. No NM cable is mentioned, still original main thread, dealing with the THHN. Whenever you click on a thread midstream, it becomes #1 in THAT display, so #8 can refer to any wehre in the thread.

********************************************************
When the info about this subject from UL was previously posted I recall that UL removed the plastic outer covering before performing dielectric tests.

I also recall they said the plastic was only providing mechanical and....

Quote:
Originally Posted by captaincrab55
Back in 1974 my instructor taught us that the outer clear jacket is what made THHN gasoline and oil resistant....



...chemical protection. :smile:
 
weressl said:
So where is the NM in that post? It refers to generic cable "sheets". Incidentaly the proper term is "jacket".
Click to expand...

Laszlo, you must be reading over it so I'll highlight it for you in the excerpt below


It's not just the nylon covering on THHN/THWN, we learned, but the sheaths on cable assemblies also often are optional. A cable installer nicked the sheath of a nonmetallic cable installed in a dry indoor location,
Click to expand...


Nonmetallic Cable is the same as NM.

Roger
 
Laszlo, can you see the attachment below?

It's not just the nylon covering on THHN/THWN, we learned, but the sheaths on cable assemblies also often are optional. A cable installer nicked the sheath of a nonmetallic cable installed in a dry indoor location,
Click to expand...


If you can tell me what is in red, if you can't, I think I see where your problem is.

Roger
 
weressl said:
Nonmetallic cable can be a host of other cables. A nylon rope is a nonmetallic cable.
Click to expand...
The problem is, a nylon rope is not included in article 334 nor is it is manufactured by Southwire.

Roger
 
jim dungar said:
If gasoline and grease protection is not required there is no need to repair or replace the cable.
edit: grammar
Click to expand...

Isn't that a judgment call that the AHJ may not accept? The requirement was to pull THHN conductors. After the damage to the cable, it no longer fully meets the THHN requirements, so what do you have in place?

The problem with Code enforcment is that it is subject to a subjective interpretation by the AHJ who may or may not be right. It does not completely relieve you - the installer - of liability.
 
weressl said:
Yep, my point exactly. Context is important and accuracy in language use is also critical.
Click to expand...
True, and in as much as this conversation is dealing with electrical conductors and cables, NM cable as defined in NEC article 334 would be accurate, not nylon rope.

NM as defined in article 334 would also be what was being discussed by Dave Mercier from "Southwire"

334.2 Definitions
Nonmetallic-Sheathed Cable. A factory assembly of two or more insulated conductors enclosed within an overall nonmetallic jacket.
Type NM. Insulated conductors enclosed within an overall nonmetallic jacket.
Type NMC. Insulated conductors enclosed within an overall, corrosion resistant, nonmetallic jacket.
Type NMS. Insulated power or control conductors with signaling, data, and communications conductors within an overall nonmetallic jacket.
Click to expand...

But in any instance, nylon rope, nylon jackets, and NM cable sheaths have nothing to do with the dielectric strength of a conductors insulation :wink:

Roger
 
weressl said:
Isn't that a judgment call that the AHJ may not accept? The requirement was to pull THHN conductors. After the damage to the cable, it no longer fully meets the THHN requirements, so what do you have in place?
Click to expand...

The AHJ enforcing the NEC would have a hard time citing a specific article that has been violated.

An AHJ enforcing customer specifications is not constrained by little details like a manufacturers acceptance or even a UL standard.

Personally, I have never seen a general wiring specification that restricted insulation to THHN only.
 
Laszlo is correct in his fundamental terminologies. The term cable implies multiple strands. In the most general sense, a solid #12 would simply be a wire, and a stranded #12 would technically be cable. However, within the electrical world cable has a slightly more specific meaning. See definition 3a in the link above.

With regard to “sheath/jacket,” he is also correct.

From (a very old copy) of ICEA S-95-658:
In classifying jackets and sheaths in these standards, the term '”jacket" refers to nonmetallic coverings and "sheath" refers to continuous metallic coverings.
Click to expand...
I note that while Article 338 is titled “Nonmetallic-Sheathed Cable,” the cable constructions are properly described as “jacketed.”

ICEA S-95-658 has been absorbed into NEMA 70WC, but I don't believe the terminology has changed. I don’t have a current copy of either immediately available and what I do have is so old it doesn’t recognize the “-2” markings for THHN, THWN, etc. It does however imply in Table 3-5 that, at the time at least, the nylon was considered part of the insulation system.

Additional Note: the definitions in the link above are consistent with Webster’s Collegiate Dictionary, 11th edition. From the NFPA Manual of Style:
3.1.2 Where terms are not defined in this chapter or within another chapter, they shall be defined using their ordinarily accepted meanings within the context in which they are used. Webster’s Collegiate Dictionary, 11th edition, shall be the source for the ordinarily accepted meaning.
Click to expand...

Edit: italicized "cable" in the second sentence
 
Last edited:
rbalex said:
Laszlo is correct in his fundamental terminologies. The term cable implies multiple strands. In the most general sense, a solid #12 would simply be a wire, and a stranded #12 would technically be cable. However, within the electrical world cable has a slightly more specific meaning. See definition 3a in the link above.

With regard to ?sheath/jacket,? he is also correct.

From (a very old copy) of ICEA S-95-658:

I note that while Article 338 is titled ?Nonmetallic-Sheathed Cable,? the cable constructions are properly described as ?jacketed.?

ICEA S-95-658 has been absorbed into NEMA 70WC, but I don't believe the terminology has changed. I don?t have a current copy of either immediately available and what I do have is so old it doesn?t recognize the ?-2? markings for THHN, THWN, etc. It does however imply in Table 3-5 that, at the time at least, the nylon was considered part of the insulation system.

Additional Note: the definitions in the link above are consistent with Webster?s Collegiate Dictionary, 11th edition. From the NFPA Manual of Style:


Edit: italicized "cable" in the second sentence
Click to expand...

OK Bob,

Now you're officialy hired as my Senior Advocate. Hey, the pay sucks, but think of all the glory!:wink:

Thanks,
 
Sure was a long trip to avoid the core issue that was asked in the OP.

There is no code reason that the plastic on THHN has to be repaired or the conductors replaced in 'normal' conditions. :)

Of course the customer may have stricter specs but that is another topic altogether.
 
celtic said:
Nope, a whisper involves some sort of secrecy...what we have here is all out in the open.
Click to expand...

Chinese whisper is a game where you whisper something into somebody else's ear and that somebody does the same thing to another person and so on. At the end of the chain, the last person announce what he heard. Most of the time it bears no resemblance to what you initially said.

I believe that is the case here.

The chinese firedrill is where untold amount of people running frenzied in all different direction without appearent purpose.
 
Status
Not open for further replies.
Top