When can you use the ampacity from the 90 Degree wire column?

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stuartdmc

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I just looked up in our electrical buyers guide under lugs and it appears that they offer "All" lugs rated for 90 degrees. If this is so and all terminals are rated for 90 degrees than why cant I use the wire ampacity from the 90 degree column for my feeders?

Thanks.
 
You could, but I wouldn't. The burden of proof would be on you to show that all terminations on both ends of the feeder are rated for 90C. Unless there is a great deal of money at stake, I would not want to have that discussion (argument?) with the AHJ.
 
When can you use the ampacity from the 90 Degree wire column?

My understanding is that lugs are always rated equal to or greater than the insulation, but UL doesn't list terminations at 90 degrees - only 75. But if that's not the case anymore, I'd be interested in hearing that.
 
stuartdmc said:
I just looked up in our electrical buyers guide under lugs and it appears that they offer "All" lugs rated for 90 degrees. If this is so and all terminals are rated for 90 degrees than why cant I use the wire ampacity from the 90 degree column for my feeders?

Thanks.
Click to expand...

In a general sense, you should plan on terminations for 75C, and if using 90C wire, you can use the 90C column for your ampacity bundling adjustment and temperature correction calculations. Termination ampacity requirements apply before you include derate calculations. Wire ampacity applies after bundling and temperature derate corrections. This is the most common reason why you would use the 90C column of the NEC.

It is rare that you are able to use the 90C column of the NEC for terminations. Both sides need to be listed and labeled for 90C.

While it may be very true and very common, that lugs appear to be listed and labeled for 90C, if the lugs are on manufactured product (switches, panelboards, breakers, etc), then it is very rare (if ever) that you will see the entire manufactured assembly listed and labeled for anything higher than 75C. It is only when you use separately installed connectors on both sides, that you can take credit for the connectors' 90C rating. Split bolts, splice reducers, insultaps, insulation piercing connectors. And it is best if these are in separate enclosures from any manufactured product.

Here is a white paper that describes this in more detail:
http://static.schneider-electric.us/docs/Power Management/0110DB9901.pdf
 
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Almost all equipment is rated for 75° C even if the terminals you install are rated for 90° C.
 
infinity said:
Almost all equipment is rated for 75° C even if the terminals you install are rated for 90° C.
Click to expand...
Agreed but I thought many of the terminals today were rated 90C.. The equipment seems to be rated 75C but the terminals on some equipment is 90C--I may be wrong but that is what I thought....Guess I'll have to check
 
By the way here is a graphic that shows the lug ratings.

ry%3D400
 
Dennis Alwon said:
By the way here is a graphic that shows the lug ratings.

ry%3D400
Click to expand...

You couldn't just remove that lug that rated for 75° C and replace it with the one rated for 90° C and expect to use the 90° C rating of the conductor. The equipment that the lug is bolted to would also need to have the 90° C rating which isn't likely.
 
infinity said:
You couldn't just remove that lug that rated for 75° C and replace it with the one rated for 90° C and expect to use the 90° C rating of the conductor. The equipment that the lug is bolted to would also need to have the 90° C rating which isn't likely.
Click to expand...


I agree. I was just stating that there are 90C lugs out there.
 
Yes, there are plenty of 90°C lugs, but very little equipment that you are permitted to install those lugs and use them at 90°C, as the equipment that the lug is connected to has the 75°C restriction.
 
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