3-phase 4 wire 100 amp subpanel feeders

[jglavin427]

110.14(C)(1) tells me that for equipment rated 100A or less I need to rate the conductors at 60C, no?

 

[Dennis Alwon]

110.14(C)(1) tells me that for equipment rated 100A or less I need to rate the conductors at 60C, no?

Yes and No.. Read further in that section. If the equipment and conductors are rated 75C then you can use the 75C column.

 

[Dennis Alwon]

Check this out

(a) Termination provisions of equipment for circuits
rated 100 amperes or less, or marked for 14 AWG through 1
AWG conductors, shall be used only for one of the following:
(1) Conductors rated 60?C (140?F).
(2) Conductors with higher temperature ratings, provided the
ampacity of such conductors is determined based on the
60?C (140?F) ampacity of the conductor size used.
(3) Conductors with higher temperature ratings if the equipment
is listed and identified for use with such conductors.
(4) For motors marked with design letters B, C, or D, conductors
having an insulation rating of 75?C (167?F) or
higher shall be permitted to be used, provided the ampacity
of such conductors does not exceed the 75?C
(167?F) ampacity.

 

[roger]

Yes and no, see 110.14(C)(1((a)(3) for the no part.

Roger

 

[roger]

Or what Dennis already said.

Roger

 

[curt swartz]

Just wondering, when using #2 AWG instead of #3 AWG do you use a larger EGC or are you using a metallic raceway as the EGC?

I think I'll plead the 5th.

 

[GoldDigger]

I think I'll plead the 5th.

Pass the 5th and a glass and I will plead with you.
.

 

[jglavin427]

Yes and No.. Read further in that section. If the equipment and conductors are rated 75C then you can use the 75C column.

Thanks for jogging my memory. I'm not sure how I missed that sentence when re-reading the section. As an engineer I don't explicitly require 75C terminations on all equipment, so for <100A I always just size according to the 60C column. Sometimes you do something a certain way for so long that you forget the original reason you did it that way.

 

[Dennis Alwon]

Thanks for jogging my memory. I'm not sure how I missed that sentence when re-reading the section. As an engineer I don't explicitly require 75C terminations on all equipment, so for <100A I always just size according to the 60C column. Sometimes you do something a certain way for so long that you forget the original reason you did it that way.

Almost all equipment today is rated 75C. I have not seen a 60C piece of equipment that is new. Basically we just assume 75C unless there is an old panel that we are dealing with.