UL internal wiring

[LMAO]

I was wondering if anyone here is familiar with UL 508A (control panels)? It requires internal wirings to be 90?C; then it directs you to table 28.1. But the problem is that there is no 90?C column in table 28.1; only 60?C and 75?C!

really confusing...:?

 

[templdl]

http://www.armstrongssupply.com/wire_chart.htm

 

[SG-1]

It may be telling you that the wire must be rated for 90 degrees C, but to use the 60 or 75 degree column to determine the gauge. There are not any device terminals I know of that are rated for 90 degrees C.

 

[Jraef]

It may be telling you that the wire must be rated for 90 degrees C, but to use the 60 or 75 degree column to determine the gauge. There are not any device terminals I know of that are rated for 90 degrees C.

That's exactly what it means. The insulation must say 90C, but you size it based on the 60 or 75C ratings. Mainly it's to be extra conservative, but another reason is that generally terminals are not rated above 75C.

 

[templdl]

Take a look at the latest edition of NFPA 79, Electrical Standard for Industrial Machinery section 15, Conductors. I have an old 1997 copy which obviously must have been updated by now.