Difference between THWN and THWN-2?

[foo1bar]

yeah, the Enphase trunk wires are THWN-2 rated, those will go into a Jbox, then inside of that Jbox I will transition to THWN and down EMT. From NEC perspective I should be fine?

You should do check for amp capacity of your wire after taking into account the temperature of the conduit's environment, and the bundling of conductors, and the amp capacity of the wire (using the 90C or 75C rating for that temp derating calculation.
most likely after all the calculations for derating it'll be that your 10AWG is capable of >30A under those rules. And you'll be limited to the 30A for 10AWG because of the 60C rating at the connectors.
But without knowing the temperature you're dealing with - or the number of current carrying wires in the conduit (nor even what size wire you're using) I can't say for sure that the ampacity after derating is unimportant.

[foo1bar]

The "-2" rating withstands degridation from UV light and can be exposed to the sun.

I have never seen that.
Everything I have seen is THWN = 75'C rated in wet env. while THWN-2 is 90'C rated in wet env.

THWN/THHN is 75/90 degree C rated. While THWN-2/THHN is 90 degree C rated for both.


I think there's a good chance that the temperature rating doesn't really matter for the OP's use.
Mainly it would allow multiple 10AWG circuits in a conduit and still be OK to handle 30A.
There's a whole "derating for multiple conductors in conduit" and higher temps than 30C (86F) that should be done for the wires in the conduit.

If you want to run the wire exposed it will need to be "-2" rated. I believe most panels have "-2" rated wire which terminate to an MC4 connector.

I have only seen MC4 connectors on PV-wire (which has UV exposure rating)
I would not expect to see an MC4 on a THWN/THHN wire. And I would not expect to see any THHN/THWN outside of a raceway - not unless it's rated under an additional code beyond THHN/THWN. (I don't know of any that is - but I don't claim to know every product, so feel free to prove me wrong)

[SunEagle]

yeah, the Enphase trunk wires are THWN-2 rated, those will go into a Jbox, then inside of that Jbox I will transition to THWN and down EMT. From NEC perspective I should be fine? UV isnt getting into EMT/Jboxes right?

If UV gets into a box or EMT then we all have a really big problem because the sun has heated up and sent us a very powerful CME.

[Duxa]

yeah, the Enphase trunk wires are THWN-2 rated, those will go into a Jbox, then inside of that Jbox I will transition to THWN and down EMT. From NEC perspective I should be fine? UV isnt getting into EMT/Jboxes right?

[SunEagle]

Thanks. So I should be fine running THWN in EMT on the roof? Dont have to get THWN-2 ? Because I kind of already ran it before realizing that the Lowes version was different from Home Depot version. Or is the inspector not gonna like seeing THWN in EMT on the roof? The entirety of it is inside EMT and Jboxes.

While I can't say exactly what the inspector will agree with, I can say that THWN in conduit (rigid, EMT, pvc) should be acceptable. If you want to run the wire exposed it will need to be "-2" rated. I believe most panels have "-2" rated wire which terminate to an MC4 connector.

[Duxa]

The "-2" rating withstands degridation from UV light and can be exposed to the sun. The THWN or THHN need to be in a raceway (conduit or pipe). The "W" allows for installations in wet areas or outside.

Thanks. So I should be fine running THWN in EMT on the roof? Dont have to get THWN-2 ? Because I kind of already ran it before realizing that the Lowes version was different from Home Depot version. Or is the inspector not gonna like seeing THWN in EMT on the roof? The entirety of it is inside EMT and Jboxes.

[SunEagle]

Hi all, I am curious what the difference between THWN and THWN-2 are? My googling skills seems to be failing me as I cant find an answer to this question.

Home Depot sells THHN that says THWN-2 on the jacket, Lowes sells the same brand same looking THHN that says THWN on the jacket. Both are rated to withstand oils/gasoline and are rated up to 90 degrees C.

I know that -2 means its dual rated for wet and hot locations. But based on the jacket and the name "W" means wet, and temperature rating is the same between the two at 90C. So whats the difference then?

The "-2" rating withstands degridation from UV light and can be exposed to the sun. The THWN or THHN need to be in a raceway (conduit or pipe). The "W" allows for installations in wet areas or outside.

[Duxa]

Hi all, I am curious what the difference between THWN and THWN-2 are? My googling skills seems to be failing me as I cant find an answer to this question.

Home Depot sells THHN that says THWN-2 on the jacket, Lowes sells the same brand same looking THHN that says THWN on the jacket. Both are rated to withstand oils/gasoline and are rated up to 90 degrees C.

I know that -2 means its dual rated for wet and hot locations. But based on the jacket and the name "W" means wet, and temperature rating is the same between the two at 90C. So whats the difference then?