310.16

[mstrlucky74]

When sizing conductors and temp ratings at terminals on both ends are 90 degree you can use 90 degree column correct?

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[texie]

When sizing conductors and temp ratings at terminals on both ends are 90 degree you can use 90 degree column correct?

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That's a big maybe. If you are connecting to, say, a breaker, just because it has a 90 degree terminal does not make it a 90 degree device. Very little equipment is rated for 90 degree terminations.

 

[infinity]

When sizing conductors and temp ratings at terminals on both ends are 90 degree you can use 90 degree column correct?

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Short answer is no. You would use the 75° C ampacity. You could use the 90° ampacity for derating purposes.

 

[david luchini]

If the short answer is no, then the long answer is yes. You could certainly introduce 90deg splice blocks into a feeder run to use the 90deg conductor ampacity in the middle section, between the 90deg terminations.

In other words, 75deg ampacity at each end and 90deg ampacity in the middle.

 

[kwired]

When sizing conductors and temp ratings at terminals on both ends are 90 degree you can use 90 degree column correct?

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The key here is whether you truly have 90C terminations. Most 600 volt and less equipment you will be limited to 75C unless you did something like david L mentioned and added 90 C splicing methods somewhere in between original points of termination.

 

[drktmplr12]

If the short answer is no, then the long answer is yes. You could certainly introduce 90deg splice blocks into a feeder run to use the 90deg conductor ampacity in the middle section, between the 90deg terminations.

In other words, 75deg ampacity at each end and 90deg ampacity in the middle.

you would need a larger gauge 75deg conductor at each end

 

[Strathead]

That's a big maybe. If you are connecting to, say, a breaker, just because it has a 90 degree terminal does not make it a 90 degree device. Very little equipment is rated for 90 degree terminations.

Can you show me an example of this? If the breaker has 90 degree terminations it seems like it would be that you would use the 90 degree table of 310.16 per 110.14(C)

 

[augie47]

Can you show me an example of this? If the breaker has 90 degree terminations it seems like it would be that you would use the 90 degree table of 310.16 per 110.14(C)

110.14(C) uses the term "equipment" in limiting the ampacity based on termination ratings. The lugs might well be rated 90° but the equipment is most often not.

 

[Strathead]

110.14(C) uses the term "equipment" in limiting the ampacity based on termination ratings. The lugs might well be rated 90° but the equipment is most often not.

Doesn't the breaker have the termination rating on it?

 

[augie47]

Doesn't the breaker have the termination rating on it?

Everyone I ever looked at did and the two here on my desk do (60-75°)

 

[kwired]

Doesn't the breaker have the termination rating on it?

If it is a removable type of lug, there is pretty good chance the lug itself is marked 90C, but that is a stand alone marking. The breaker itself is going to be rated (and marked somewhere) for 75C. Doesn't matter if you attached a lug with stand alone rating of 150C, it still is only good for 75C when attached to the breaker, and for that matter the 90C conductor landed in it is still only good for 75C ampacity as well, at that termination. You can still make ampacity adjustments based on the 90C insulation rating.

 

[Strathead]

Everyone I ever looked at did and the two here on my desk do (60-75°)

Right so I don't understand the issue. The terminations are rated 75 so that is the column. If it was rated 90 you would use the 90.

 

[Strathead]

If it is a removable type of lug, there is pretty good chance the lug itself is marked 90C, but that is a stand alone marking. The breaker itself is going to be rated (and marked somewhere) for 75C. Doesn't matter if you attached a lug with stand alone rating of 150C, it still is only good for 75C when attached to the breaker, and for that matter the 90C conductor landed in it is still only good for 75C ampacity as well, at that termination. You can still make ampacity adjustments based on the 90C insulation rating.

texie didn't say lug, he said 90 terminal. I get it. My original intent wasn't to be difficult it was to find out if I needed to learn something. I didn't. It is as I understood it, that is fine.

 

[augie47]

As others have pointed out, I think the confusion comes from the fact that a lot of terminals (ie: the actual 'lug' where you connect the wire) are rated at 90° which lead some to feel they are ok with a 90° ampacity.

 

[Dennis Alwon]

Some terminations are 90C however the equipment is rated 75C therefore you have to use the 75C rating. 90C is used for de-rating or as in the case below

 

[david luchini]

you would need a larger gauge 75deg conductor at each end

I think that's what I said.

 

[texie]

Here is what UL says about this in Product Catagory AALZ:
"

A 75 or 90°C temperature marking on a terminal(e.g., AL7, CU7AL, AL7CU or AL9, CU9AL, AL9CU) does not in itself indicate that 75 or 90°C insulated wire can be used unless the equipment in which the terminals are installed is marked for 75 or 90°C."​