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Attic Rat

As caselec pointed out rolls of THHN are dual rated THHN/THWN.

When used in wet locations it is rated by the 75 C column as THWN when used in dry locations it is THHN and the ratings of the 90 C column apply. (for certain things.

NM striped or unstripped is never allowed in wet locations.

Now is outside in liquid tight a wet location, I know underground is always a wet location but above ground in a closed raceway. I do not think so.


I also see the following as saying if the product was not FMC (ie Liquid tight) the conductors would not have to be wet location rated.


What do you all think?

We always use THWN or RHW so it does not come up, and experience tells me the liquid tight is more likely to hold water in than out.

But is this truly a code violation?


[This message has been edited by iwire (edited 02-21-2004).]

Once again, the code seems to condradict itself. Let's break this apart...

"In wet locations unless the conductors are approved for the specific conditions..."

OK, THWN is obviously the call here, but then:

"and the installation is such that liquid is not likely to enter raceways or enclosures to which the conduit is connected"

If liquid (water, in this case) is "not likely to enter the raceway or enclosure", doesn't that make it (by default) a not-wet (i.e. "dry", maybe "damp") environment, thus suitable for THHN?

Sheeesh... sometimes it makes more sense if the AHJ just gets "the face" and tells you "cuz I says so..."

I think the "carlon flex" being refered to is actually LFNC. I have seen it at home Depot and Lowe's, basically they sell it in a 6' whip, ant it is indeed LFNC.

With that in mind, I think Bob's opinion is quite valid. No red-tag from me.


BTW: Good work Bob.

The conductors insulation is tested for breakdown by verious test methods, a non type W rating. will break down with moisture, when this non W rated insulation is pulled in sealtight and used outdoors, the changes in temp. will produce moisture inside the sealtight, as the non W insulation ages, it may be more likley to fail under moisture conditions.

Are the wires in NM made to be used as seperate conductors?? or are they made to be part of a cable assy.?? On a roll of THHN there are markings telling size, listing, temps etc, are those on the individual wires in NM??.I've never seen them. I don't see the problem in practical terms but as far as code goes I say no but I doubt I would have ever seen it to say no

LK I agree with you 100%.

I just do not see any code that the inspector could use to fail this.

Supposedly Liquid tight is dry inside.

By the way, Thanks Ryan.

Bob

Yes, inside a building, where temp changes are small, the moisture condition is less likely. One tragdy that you may remember, was the air crash just off BC, the wires were in the upper air frame of the cabin, the differance in temp. between an air cooled cabin, and the upper frame open raceway, caused condension and an investigation showed aging wiring had failed due to moisture on the insulation.
When they refer to wet locations, it is best to consider all the exposure including moisture, since this is part of the insulation testing. We may not find exact wording in the code, however manufactures list for proper application.

In my opinion all raceways installed outside are wet locations.
Don

Don,
Yup, moisture is water, and water is wet.

It seems to me that an airconditioning or heatpump condenser would have a tendency to cause even more condensation than other installations. After all, its main function is to change temperature, and it goes through cycling periods...S