tffn wire

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jcole

Senior Member
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Lawrenceburg, Kentucky
Hello guys and gals.

I have a salesman telling me that tffn wire would be ok to use in underground conduit run. My research tells me that it should only be used in dry locations. I would consider the underground conduit a wet location. What is your opinion on this? He says it basically the same thing as mtw, thhn, thwn. The reason he is quoting this instead of thhn/thwn dual rated wire is because I need the wire to be 16awg.
 
I never heard of TFFN. Do you mean THHN? Usually THHN is dual rated and is also THWN and can be used underground in conduit. If it is just THHN- I haven't seen that in a while- then it cannot be used in wet locations.

I guess I should have read the entire post. IMO TFFN has no "W" so unless it is dual rated I would say no.
 
BTW, I do not see TFFN listed in art. 310. Unless they can provide documentation I wouldn't do it. Use #14- if you can
 
The only applications I have used TFF or TFFN in is for F/A (see 760.49(B)) and some low voltage controls, it is only for dry locations. Many salesmen will tell you anything to sell somrething, believe it or not. :D

Roger
 
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