Weaseling into the 90 degree column

[electrofelon]

For a given size OCPD, can one use 75 degree sized wire for the terminations, and then splice these stubs to smaller wire sized by the 90 degree column, assuming the splicing device and wire is rated for 90 degrees?

Example: The situation in the "#2 AL feeders" thread (http://www.mikeholt.com/code_forum/showthread.php?t=82086) where 310.15(B)(6) was used in a commercial application. Use a 1 foot piece of #1 AL on the 100A breaker and splice it to the #2(100A, 90 degree column), then do the same on the other end?

For smaller circuits, I noticed that Ideal wire nuts are rated 105 degrees, but I couldnt find a temperature rating on a split bolt.

I dont need to do any weaseling right now, just an academic question.

 

[mdshunk]

For smaller circuits, I noticed that Ideal wire nuts are rated 105 degrees, but I couldnt find a temperature rating on a split bolt.
.

It might say AL9CU, with the 9 indicating 90 degrees.

 

[LarryFine]

For a given size OCPD, can one use 75 degree sized wire for the terminations, and then splice these stubs to smaller wire sized by the 90 degree column, assuming the splicing device and wire is rated for 90 degrees?

I would think so. I once spliced copper onto aluminum SE cable feeding an air-handler labeled for copper only.

(Okay, I mean I hope so.)

 

[electrofelon]

I would think so also, just wondering if I was looking over something. It seems like this option never comes up in an undersized wire situation.

 

[jim dungar]

Circuit breaker and fused switch terminations are tested with 4 feet of conductor. So, can you infer that after 4' the temperature rating is not a problem?

 

[buck33k]

I was under the impression that the rating of the enclosure would restrict this.

For instance, many lugs are rated 90 degrees but a can or j-box would only have a 75 degree rating limiting the ampacity of the conductor.

 

[jwelectric]

What is the weakest link of this circuit? Would it be 75 degrees?

 

[buck33k]

What is the weakest link of this circuit? Would it be 75 degrees?

Mike
I'd say yes, 75 degrees.

 

[bob]

For a given size OCPD, can one use 75 degree sized wire for the terminations, and then splice these stubs to smaller wire sized by the 90 degree column, assuming the splicing device and wire is rated for 90 degrees?
Example: The situation in the "#2 AL feeders" thread (http://www.mikeholt.com/code_forum/showthread.php?t=82086) where 310.15(B)(6) was used in a commercial application. Use a 1 foot piece of #1 AL on the 100A breaker and splice it to the #2(100A, 90 degree column), then do the same on the other end?

If you have a continuous load of 100 amps the #2 is going heat up to 90C. That may heat the #1 (1 ft long) to a temp over 75C.

 

[jim dungar]

I was under the impression that the rating of the enclosure would restrict this.

For instance, many lugs are rated 90 degrees but a can or j-box would only have a 75 degree rating limiting the ampacity of the conductor.

Actually the rating of the lug is irrelevant. In fact very few if any, "lugs" have been rated less than 90 for almost 15 years.

What counts is the rating of the device termination, which includes the enclosure among other things.

 

[electrofelon]

So It looks like 110.3(B) (install per manufactures instructions) is the only potential deal breaker for this weasely act, however I dont recall ever seeing a temperature limitation for the 'general areas' of equipment (well pvc but thats 90 degrees anyway). I would assume that a few feet of wire between the splice and the breaker/termination would be sufficient to keep the termination below 75 degrees.