Conductor insulation rating

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elmundogrande

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When did the wiring manufactures stop making a THWN-2 in sizes 10 AWG and smaller. I had an inspector try to make me change the wire on two solar jobs I did cause the wire was dual rated THHN/THWN and it could not run on the roof. I told him that code 310.15 (A)(2) allows me to come out of the attic to my J-Box(AC micros) and less than 3 feet on a 60 foot run. So now if we run wires on the roof exposed to the sun less than 30 amps we need to use a size #8 AWG a 90*C wire. I check the supply house and big hardware stores size 10 AWG and smaller dual rated wire 90*C THHN(dry) 75*C THWN(wet). Am I correct cause on the blue prints I keep seeing #10 THWN-2
 
elmundogrande said:
When did the wiring manufactures stop making a THWN-2 in sizes 10 AWG and smaller. I had an inspector try to make me change the wire on two solar jobs I did cause the wire was dual rated THHN/THWN and it could not run on the roof. I told him that code 310.15 (A)(2) allows me to come out of the attic to my J-Box(AC micros) and less than 3 feet on a 60 foot run. So now if we run wires on the roof exposed to the sun less than 30 amps we need to use a size #8 AWG a 90*C wire. I check the supply house and big hardware stores size 10 AWG and smaller dual rated wire 90*C THHN(dry) 75*C THWN(wet). Am I correct cause on the blue prints I keep seeing #10 THWN-2
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THWN-2 is not made for use outside of a conduit, in this application. Look for USE-2/RHH/RHW-2, or PV Wire.
 
It was in the conduit

It was in the conduit

Carultch said:
THWN-2 is not made for use outside of a conduit, in this application. Look for USE-2/RHH/RHW-2, or PV Wire.
Click to expand...

This is the feed to the micros on the roof which was ran through the attic and came up to a J-Box next to the array and the Inspector said that it had to be #8 THWN-2 cause they don't make it in #10 or smaller THWN-2 and it has to be a 90* rated insulated conductor for wet location in a raceway like RHW-2, THWN-2, USE-2...... exposed to sun rays. So after going around checking #10 THHN and smaller are 90*C dry and 70*C wet THWN with that being said watch out for your designs and make sure you have the right wire size.
 
elmundogrande said:
This is the feed to the micros on the roof which was ran through the attic and came up to a J-Box next to the array and the Inspector said that it had to be #8 THWN-2 cause they don't make it in #10 or smaller THWN-2 and it has to be a 90* rated insulated conductor for wet location in a raceway like RHW-2, THWN-2, USE-2...... exposed to sun rays. So after going around checking #10 THHN and smaller are 90*C dry and 70*C wet THWN with that being said watch out for your designs and make sure you have the right wire size.
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According to Southwire's products page you are correct. Their #14-#10 is THHN/THWN, THWN-2 doesn't begin until #8 and larger. What was the problem with the 75° C conductor, was it too small after ampacity correction for use on the roof? Under the 2017 NEC if your distance above the roof is 7/8" or greater no temperature adder is required.
 
elmundogrande said:
This is the feed to the micros on the roof which was ran through the attic and came up to a J-Box next to the array and the Inspector said that it had to be #8 THWN-2 cause they don't make it in #10 or smaller THWN-2 and it has to be a 90* rated insulated conductor for wet location in a raceway like RHW-2, THWN-2, USE-2...... exposed to sun rays. So after going around checking #10 THHN and smaller are 90*C dry and 70*C wet THWN with that being said watch out for your designs and make sure you have the right wire size.
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#10 THWN-2 not available? I don't believe it. Nearly every datasheet I've ever seen for this type of wire goes down at least as small as #14. The sunlight resistance may be a function of size, as well as color. But the THWN-2 spec applies to all sizes in the family.
 
Carultch said:
#10 THWN-2 not available? I don't believe it. Nearly every datasheet I've ever seen for this type of wire goes down at least as small as #14. The sunlight resistance may be a function of size, as well as color. But the THWN-2 spec applies to all sizes in the family.
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I can't think of a datasheet that does show THWN-2 smaller than #8. Southwire, Anixter, General Cable, Cerro Wire...all #8 and larger for THWN-2.

There is a logic to the #8 and above cutoff, relating to 240.4(D)...

#8 THWN-2 has an ampacity of 50 at 75 degrees, but can be derated from 55 Amps.

#10 THWN can be protected up to 30A, but can be derated from 35 Amps,
#12 THWN can be protected up to 20A, but can be derated from 25 Amps, and
#15 THWN can be protected up to 15A, but can be derated from 20 Amps.

(You would lose that derating ability for circuits that don't fall under the Small Conductor requirements)
 
david luchini said:
I can't think of a datasheet that does show THWN-2 smaller than #8. Southwire, Anixter, General Cable, Cerro Wire...all #8 and larger for THWN-2.

There is a logic to the #8 and above cutoff, relating to 240.4(D)...

#8 THWN-2 has an ampacity of 50 at 75 degrees, but can be derated from 55 Amps.

#10 THWN can be protected up to 30A, but can be derated from 35 Amps,
#12 THWN can be protected up to 20A, but can be derated from 25 Amps, and
#15 THWN can be protected up to 15A, but can be derated from 20 Amps.

(You would lose that derating ability for circuits that don't fall under the Small Conductor requirements)
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Can you explain to me what I'm missing, when I read the following datasheet?
https://www.encorewire.com/wp-content/uploads/EncoreWire-THHN-SSE.pdf

"14 AWG THROUGH 8 AWG: ENCORE*WIRE*CORP*(SIZE)*TYPE*MTW*OR*THHN*OR*THWN-2*GR2*VW-1*600V*(UL)*OR*AWM*OR*C(UL)*TYPE*T90*NYLON*OR*TWN*75 SUPERSLICK ELITE"

That seems to state that it is THWN-2 in sizes 14 through 8. What am I missing?
 
Carultch said:
"14 AWG THROUGH 8 AWG: ENCORE*WIRE*CORP*(SIZE)*TYPE*MTW*OR*THHN*OR*THWN-2*GR2*VW-1*600V*(UL)*OR*AWM*OR*C(UL)*TYPE*T90*NYLON*OR*TWN*75 SUPERSLICK ELITE"

That seems to state that it is THWN-2 in sizes 14 through 8. What am I missing?
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The "sunlight resistant" marking? The data sheet you referenced adds that marking for sizes above 8 AWG.

Cheers, Wayne
 
Raceway of the Roof

Raceway of the Roof

Here in California we just started using NEC 2014. So all I wanted to do is get the word out cause the AHJ are catching on to the #10 conductor insolation for wet location is 75* THWN, but on blue prints its still showing it as THWN-2 and all the math is at 90*C all wrong so be aware before you do and they make you change it out.
 
elmundogrande said:
Here in California we just started using NEC 2014. So all I wanted to do is get the word out cause the AHJ are catching on to the #10 conductor insolation for wet location is 75* THWN, but on blue prints its still showing it as THWN-2 and all the math is at 90*C all wrong so be aware before you do and they make you change it out.
Click to expand...
I don't think they stopped making it, your suppliers may have stopped purchasing it that way though.

All it takes is one bean counter in the supply company that wants to save a dime on every 100 feet purchased to make something like that happen.
 
Facts- Manufacturers have not stopped making THHN/THWN-2 is smaller sizes. They just might offer an option that doesn't include the "-2" component which can create an issue for engineers who's specs do not specify the proper nomenclature but thats another topic all together.

As additional info, the trend now is to create an "ALA CART" approach to wire manufacturing. For example, not all THHN/THWN-2 or XHHW-2 for that matter will be VW-1 rated. The customer (ultimately the distributor) can offer to have a wire with multiple ratings such as VW-1, FT-4/IEEE 1202. Now, FT-2 is mandatory for UL 44 but not for UL 83. Now, when UL 83 is to be VW-1 rated then it must pass both FT-2 and VW-1 to obtain such a mark. Interesting enough, the FV-1 test is the base minimum test for UL 83 (Thermoplastic wire) in the US and Mexico at this time...in Canada it's FT-1 but you get the jist.

Anyway, point is....it used to be that wire and cable folks threw everything on the wire....now they most throw the minimums required and allow the end user to select the level of testing to be marked on the wire.
 
Wire for sale

Wire for sale

kwired said:
I don't think they stopped making it, your suppliers may have stopped purchasing it that way though.

All it takes is one bean counter in the supply company that wants to save a dime on every 100 feet purchased to make something like that happen.
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When I check with some local electrical suppliers and big box stores they only had 14-10 in THHN - THWN and when I called South Wire they said they only make it in THHN - THWN-2 in size #8 and larger
 
MasterTheNEC said:
Facts- Manufacturers have not stopped making THHN/THWN-2 is smaller sizes. They just might offer an option that doesn't include the "-2" component which can create an issue for engineers who's specs do not specify the proper nomenclature but thats another topic all together.

As additional info, the trend now is to create an "ALA CART" approach to wire manufacturing. For example, not all THHN/THWN-2 or XHHW-2 for that matter will be VW-1 rated. The customer (ultimately the distributor) can offer to have a wire with multiple ratings such as VW-1, FT-4/IEEE 1202. Now, FT-2 is mandatory for UL 44 but not for UL 83. Now, when UL 83 is to be VW-1 rated then it must pass both FT-2 and VW-1 to obtain such a mark. Interesting enough, the FV-1 test is the base minimum test for UL 83 (Thermoplastic wire) in the US and Mexico at this time...in Canada it's FT-1 but you get the jist.

Anyway, point is....it used to be that wire and cable folks threw everything on the wire....now they most throw the minimums required and allow the end user to select the level of testing to be marked on the wire.
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I am just dying to know, how much more it costs to add these various ratings - RHH-2 vs just USE-2, sun-res, -2, FT, CT use, etc. I really have to guess that it is very minimal cost adder and the added simplicity for everyone, less product variety, production runs, and stock would make it worthwhile.....I can dream.
 
Well.....you have to understand the context of a production that runs 24/7-365. It is a huge cost factor when millions of feet are produced.

Sent from my SAMSUNG-SM-G935A using Tapatalk
 
MasterTheNEC said:
Well.....you have to understand the context of a production that runs 24/7-365. It is a huge cost factor when millions of feet are produced.

Sent from my SAMSUNG-SM-G935A using Tapatalk
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Which only comes to 20 cents per hundred feet, maybe a dollar?

Demand will dictate they make what will sell, problem is the bean counter at the supply house decides to save that 20 cents to a dollar for every hundred feet. Nobody notices much of anything until inspectors start noticing people are using conductors only rated 75C in certain conditions as 90C conductors. When enough supply house customers demand -2 conductors they may eventually lay down that extra 20 cents to a dollar to ensure that is what gets ordered.
 
Huge costs to Manufacturer's and it adds up when we produce millions of feet a month. Also in many cases the pellets for thermostat already have specific additives and thermoplastic required additives placed into the mixture and indeed .30 a foot adds up when dealing with millions of feet Per Color......Per Product and so on. Most of the time VW-1 Is only in THHN/THWN-2 while it's optional in both T and X....

Sent from my SAMSUNG-SM-G935A using Tapatalk
 
So where did you get this value "Which only comes to 20 cents per hundred feet, maybe a dollar?"

Do you assist in wire manufacturing?

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MasterTheNEC said:
Huge costs to Manufacturer's and it adds up when we produce millions of feet a month. Also in many cases the pellets for thermostat already have specific additives and thermoplastic required additives placed into the mixture and indeed .30 a foot adds up when dealing with millions of feet Per Color......Per Product and so on. Most of the time VW-1 Is only in THHN/THWN-2 while it's optional in both T and X....

Sent from my SAMSUNG-SM-G935A using Tapatalk
Click to expand...
You do pass those costs on when selling the product don't you?

It is the those purchasing on a wholesale level that determines what is available at supply houses and retail outlets. If you make it and their customers demand it, they will buy it. The bean counters at the supply house only see dollars and don't always see those minor differences or know what the buyer wants, until the buyer lets them know what they want. They will pass any extra cost on when they sell also, once they learn the buyer still prefers that product. Some may not realize there is no -2 rating until they encounter inspectors that are looking for it where needed.

I haven't looked at any of the conductors I have purchased for some time now, maybe need to check to see if there is still a -2 rating on what I have been getting. You kind of assume that is what you are getting when you noticed it was there in the past.

Bottom line is it isn't that -2 conductors are not manufactured, it is the middle man that determines what is available at supply houses and retail outlets. Any supply house employee that tells you they don't make it is wrong. What they should tell you is they don't have it.... because they are too cheap to buy it:)
 
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