NEC Article 110.14(C)

[amamun]

NEC 2008 Article 110.14 (C):
The temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any connected termination, conductor, or device. Conductors with temperatur ratings higher than specified for terminations shall be permitted to be used for ampacity adjustment, correction or both.

I read it many times but I did nor quite understand what it want to mean?
I will appreciate if anybody can explain thie article with examples.

Thanks,
Mamun

 

[iwire]

It means use the lowest value.

You could have a circuit leaving a breaker with a 75 C terminal using 90 C conductors and ending on a 60 C terminal at the device. In this case you would have to use the 60 C value for the entire circuit because of that one device terminal being 60 C.

 

[infinity]

Here's a good graphic. Take a look and see if it's seems somewhat clearer.

Welcome to the Forum.

 

[ronmath]

Interesting, I was just told this this morning. "If you run from a 75C rated breaker to a j-box at least 3-feet away, then splice with 90C rated wire to a j-box at least 3-feet from a 60C rated plug, you can use the 90C column rating for the middle of the run. Has anybody done something like this? I think it may meet code, but you might have a hard time explaining it to some inspectors. Let me know what you think.

 

[iwire]

Interesting, I was just told this this morning. "If you run from a 75C rated breaker to a j-box at least 3-feet away, then splice with 90C rated wire to a j-box at least 3-feet from a 60C rated plug, you can use the 90C column rating for the middle of the run. Has anybody done something like this? I think it may meet code, but you might have a hard time explaining it to some inspectors. Let me know what you think.

In my opinion it would meet code.

I used this as an example in another thread where this came up.

 

[JWCELECTRIC]

Here's a good graphic. Take a look and see if it's seems somewhat clearer.

Welcome to the Forum.

Infinity,

Do you have an example where the 90 degree column can be used for its ampacity? Most terminations do not exceed 75 degree.

 

[JWCELECTRIC]

Interesting, I was just told this this morning. "If you run from a 75C rated breaker to a j-box at least 3-feet away, then splice with 90C rated wire to a j-box at least 3-feet from a 60C rated plug, you can use the 90C column rating for the middle of the run. Has anybody done something like this? I think it may meet code, but you might have a hard time explaining it to some inspectors. Let me know what you think.

Ron,

I agree! If you have a 2-panels (Iwire's sketch) with 75 dergree termination at points A&B with wireway below each panel then run 90 degree cables between wireways, make splices then extend cables up to 75 degree terminations. Seems goofy!

 

[jim dungar]

Interesting, I was just told this this morning. "If you run from a 75C rated breaker to a j-box at least 3-feet away, then splice with 90C rated wire to a j-box at least 3-feet from a 60C rated plug, you can use the 90C column rating for the middle of the run. Has anybody done something like this? I think it may meet code, but you might have a hard time explaining it to some inspectors. Let me know what you think.

The UL test procedure, for breakers and fused switches, includes 4ft of conductor connected to the lug. I would use this as my distance to the j-box.

 

[JWCELECTRIC]

The UL test procedure, for breakers and fused switches, includes 4ft of conductor connected to the lug. I would use this as my distance to the j-box.

Jim,

In theroy as long as there is a junction box 4' away from the 75 degree termniation panels, I run the 90 deg cables between panels thru jboxes without splices the install is ok because my cables are THHN and they are rated in 75 & 90 deg columns!

 

[infinity]

Infinity,

Do you have an example where the 90 degree column can be used for its ampacity? Most terminations do not exceed 75 degree.

I don't and I think that you would be hard pressed to find one. :smile:

 

[iwire]

Most terminations do not exceed 75 degree.

Many wire connectors exceed 90 C, wire nuts at 105C, I am sure many compression connectors are also rated above 90 C

 

[JWCELECTRIC]

Many wire connectors exceed 90 C, wire nuts at 105C, I am sure many compression connectors are also rated above 90 C

How about breakers, disconnect/fused switches, final termination points etc.?

 

[iwire]

How about breakers, disconnect/fused switches, final termination points etc.?

I don't think any of those are rated more than 75C.

But the fact we can get 90C wire connectors allows us to do as I showed in my example.:smile:

 

[jim dungar]

How about breakers, disconnect/fused switches, final termination points etc.?

The UL requirements for these devices is 75?C conductors maximum (or is that minimum?:smile.

Even though 100% rated devices must be wired with 90?C insulated conductors, they must still be sized no smaller than the 75? column.

 

[JWCELECTRIC]

I don't think any of those are rated more than 75C.

But the fact we can get 90C wire connectors allows us to do as I showed in my example.:smile:

Bob,

I see your example where you change over from 75 to 90 deg cable, 310.16 has THHW for example, in both columns why would there be a need to provide jboxes and splices between the two points? IMO making splices creates a weak link on the cable run between the two points. I quess I would run the cable from A to B thru a couple junction boxes then put a tape ball on the cables in the jbox to make it look like a termination. Just a thought

 

[Twoskinsoneman]

100% rated devices must be wired with 90?C insulated conductors

Hey what is the code ref for this?

 

[jim dungar]

Hey what is the code ref for this?

It is not an NEC reference it is part of the UL standard.

 

[iwire]

Bob,

I see your example where you change over from 75 to 90 deg cable, 310.16 has THHW for example, in both columns why would there be a need to provide jboxes and splices between the two points?

By doing what my example shows it allows the use of smaller conductors in the middle as that set of conductors between the two junction boxes can be used at 90 C.

So instead of having to run 350 Kcmil all the way you could use 250 Kcmil for much of the run.

IMO making splices creates a weak link on the cable run between the two points.

I do not disagree but I thought we where talking about NEC requirements?

I quess I would run the cable from A to B thru a couple junction boxes then put a tape ball on the cables in the jbox to make it look like a termination. Just a thought

There would be no reason you would have to if in the example 350 was used all the way.

 

[Twoskinsoneman]

100% rated devices must be wired with 90?C insulated conductors

I'm not even sure if I've ever installed a 100% circuit breaker but I just want to point out that The UL says

"Circuit breakers intended for continuous operation at 100 percent of rated current may be marked to be connected 90(degree)C rated wire..."

Now the case may be that every single one is marked 90...I have no idea.. but I just wanted to point out the UL says it may be marked that way.

 

[Twoskinsoneman]

310.16 has THHW for example, in both columns

I'm not sure I completely understand your point but the reason for THHW in both columns is because in dry location it is rated 90 and in wet it is located 75 :smile: