THHN vs. THWN-2

[sgtsparky]

The specific question I was asking appears to be a moot point; I have not found anyone who makes THHN only wire. A client I deal with claimed to have some that they wanted to use for a PV system, but they could not document it.

I agree many years ago I forgot to order -2 and south wire only made -2 fortunately the inspector agreed after verifying, I want to say this was 20 years ago, possibly 25. The wire only had thhn on it back then but was -2

 

[kwired]

The specific question I was asking appears to be a moot point; I have not found anyone who makes THHN only wire. A client I deal with claimed to have some that they wanted to use for a PV system, but they could not document it.

More recently this probably is the case with new product. You still may want to pay attention to what you have to work with when encountering existing installations though.

 

[Jraef]

I have nothing to add, but I learned something new today. When cables started coming out showing “THHN/THWN-2”, I assumed that was shorthand for saying THHN-2 and THWN-2, but I could never get a good answer on the difference between THHN vs THHN-2. Now I know why, the -2 only applied to the THWN rating, there is no THHN-2!

<slaps forehead>

 

[LarryFine]

Now I know why, the -2 only applied to the THWN rating, there is no THHN-2!

That's because the -2 suffix indicates that the wet rating, which THHN lacks, is equal to the dry rating.