NEC 110.14(C)(1)(a)(3) vs UL white book catagory AALZ

[Cten]

Does the NEC allow #8 THWN-2 (75'C) with 50 amp 240 volt breaker rated 75'C with NEMA 14-50 receptacle marked (75'C) installed in 3/4" EMT with about 15 feet of conductor length? I assume the (75'C) marking on all components as per 110.14(C)(1)(a)(3) allow me to use the 75'C column in table 310.16 but the UL white book does not recognize the possibility.

 

[Smart $]

Does the NEC allow #8 THWN-2 (75'C) with 50 amp 240 volt breaker rated 75'C with NEMA 14-50 receptacle marked (75'C) installed in 3/4" EMT with about 15 feet of conductor length? I assume the (75'C) marking on all components as per 110.14(C)(1)(a)(3) allow me to use the 75'C column in table 310.16 but the UL white book does not recognize the possibility.

THWN-2 is a 90?C-rated conductor. Typically good on a 50A circuit unless derating takes the ampacity below the load supplied or less than or equal to the next lower standard size breaker (45A).

 

[jim dungar]

THWN-2 is a 90?C-rated conductor. Typically good on a 50A circuit unless derating takes the ampacity below the load supplied or less than or equal to the next lower standard size breaker (45A).

UL does not list any 600v maximum fuse or molded case circuit breaker for use with conductors size using the 90?C column.

 

[steve66]

Does the NEC allow #8 THWN-2 (75'C) with 50 amp 240 volt breaker rated 75'C with NEMA 14-50 receptacle marked (75'C) installed in 3/4" EMT with about 15 feet of conductor length? I assume the (75'C) marking on all components as per 110.14(C)(1)(a)(3) allow me to use the 75'C column in table 310.16 but the UL white book does not recognize the possibility.

What part of the UL white book "does not recognize the possibility"? They must recognize both the breaker and receptacle are good for 75 deg C, or those components wouldn't be listed for 75 deg C. And they surely recognize the wire is good for 75 deg C.

 

[GoldDigger]

UL does not list any 600v maximum fuse or molded case circuit breaker for use with conductors size using the 90?C column.

But the calculation for the derated ampacity in a raceway (adjustment) can still be done using the higher temperature as long as the separate calculation for ampacity at the terminal (lower temperature limit) is also met by the chosen wire size.

 

[Smart $]

UL does not list any 600v maximum fuse or molded case circuit breaker for use with conductors size using the 90?C column.

I didn't say it did... but I implied (or otherwise forgot to state) in my second sentence I was referring to the proposed 8AWG THWN-2 (assumed copper). I was not saying one could use the 90?C column for the minimum size permitted.

 

[Cten]

What part of the UL white book "does not recognize the possibility"? They must recognize both the breaker and receptacle are good for 75 deg C, or those components wouldn't be listed for 75 deg C. And they surely recognize the wire is good for 75 deg C.

AALZ, "Appliance and Utilization Equipment"
"If the equipment is only marked for use with conductors having a higher (75 or 90'C) temperature rating (wire size not specified), the 60'C ampacities (for circuits rated 100 A or less) and 75'C (for circuits rated over 100 A) should be used to determine wire size."

It appears I must size the wire for 60'C with no regard to the actual minimum rating of the components.

 

[GoldDigger]

AALZ, "Appliance and Utilization Equipment"
"If the equipment is only marked for use with conductors having a higher (75 or 90'C) temperature rating (wire size not specified), the 60'C ampacities (for circuits rated 100 A or less) and 75'C (for circuits rated over 100 A) should be used to determine wire size."

It appears I must size the wire for 60'C with no regard to the actual minimum rating of the components.

I think that I see the rationale for this, at first glance confusing, statement.
If the utilization equipment can be used with 60C wire, then using higher temp rated wire can be expected to provide higher ampacity
But if the equipment gets so hot on its own that higher temp wire MUST be used, then going to the higher ampacity rating would increase the temperature even more. Possibly above the insulation rating.
There would still be the separate parallel test that the current not exceed the terminal ratings. For this part the higher temp ampacity might be allowed.

Keep in mind that the UL language describes something for which 60C wire is not allowed. ("...only rated for higher temperature ....")

 

[Smart $]

...

Keep in mind that the UL language describes something for which 60C wire is not allowed. ("...only rated for higher temperature ....")

I'm not aware of any particular equipment where the conductor must be greater than 60?C... but IIRC, 100%-rated breakers require the use of 90?C-rated conductors, even though we must still use 75?C value for determining minimum size of the wire.

 

[GoldDigger]

I'm not aware of any particular equipment where the conductor must be greater than 60?C... but IIRC, 100%-rated breakers require the use of 90?C-rated conductors, even though we must still use 75?C value for determining minimum size of the wire.

I was thinking of high wattage luminaires for large PAR type bulbs. Possibly there are no restrictions on the wire that connects to the fixture wire though.
The requirement for 90C wire on the 100% rated breakers does sound like something that that set of sentences would be relevant to, though. It would mean that for small breakers (100A and smaller) you would actually have to calculate based on 60C and only get to use 75C when over 100A.

 

[Cten]

I was thinking of high wattage luminaires for large PAR type bulbs. Possibly there are no restrictions on the wire that connects to the fixture wire though.
The requirement for 90C wire on the 100% rated breakers does sound like something that that set of sentences would be relevant to, though. It would mean that for small breakers (100A and smaller) you would actually have to calculate based on 60C and only get to use 75C when over 100A.

In my case the issue is whether I am allowed pull #8 THWN or required to use #6. I believe the NEC allows me to use the 75'C column of table 310.16 if all my wire and terminations are rated for at least 75'C. UL White Book simply requires the 60'C column for all circuits of 100A or less.

 

[iwire]

AALZ, "Appliance and Utilization Equipment"
"If the equipment is only marked for use with conductors having a higher (75 or 90'C) temperature rating (wire size not specified), the 60'C ampacities (for circuits rated 100 A or less) and 75'C (for circuits rated over 100 A) should be used to determine wire size."

It appears I must size the wire for 60'C with no regard to the actual minimum rating of the components.

That section of the white book does not apply to a receptacle.

Receptacles are devices, not appliances or utilization equipment.

 

[steve66]

I think Iwire and Golddigger are both on the same page. The section you are quoting is for equipment that generates a lot of heat - equipment that is marked for ONLY 75 or 90 deg. conductors. In other words, its for equipment where 60 deg wire is not allowed.

60 deg wire is allowed on your breaker, and on the recetpacle.

So the paragraph you quoted doesn't apply for 2 reasons: it's not an appliance or utilization equipment like Iwire mentioned. And its not heat producing equipment that requires 75 or 90 deg. wire like Golddigger mentioned.

So the #8 wire would be good.

 

[Cten]

I think Iwire and Golddigger are both on the same page. The section you are quoting is for equipment that generates a lot of heat - equipment that is marked for ONLY 75 or 90 deg. conductors. In other words, its for equipment where 60 deg wire is not allowed.

60 deg wire is allowed on your breaker, and on the recetpacle.

So the paragraph you quoted doesn't apply for 2 reasons: it's not an appliance or utilization equipment like Iwire mentioned. And its not heat producing equipment that requires 75 or 90 deg. wire like Golddigger mentioned.

So the #8 wire would be good.

Thank You.