Electrician Talk banner
1 - 5 of 5 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter · #1 ·
I am looking for some clarification. I was given conflicting information at work today. It revolves around picking the right size wire from table 310.15.B.16.

110.14 (c)(1)(a)- States "termination provisions of equipment for circuits rated 100 amps or less, or marked for 14AWG through 1AWG conductors, shall e used on only one of the following".
(a) Conductors rated 60 degrees C.

110.14 (c)(1)(4)B)- Stats " Termination provisions of equipment for circuits rated over 100 amps or marked for conductors larger than 1 AWG shall be used only for one of the following"
(1) Conductors rated 75 degrees C.

The following has been my understanding of table 310.15.B.16:
90 degree column is used only for derating and ambient temperature correction or both

75 degree column is used only for the conductors with an insulation value of 75 degrees above the column. Or if both ends of the termination are rated at 75 degrees

60 degree column is used only by the conductors with the insulation value listed above the top of the column. It is the "worst case scenario" column. It is also used for when both/ one end of the termination temp rating is unknown.
(for example an 8awg THWN conductor would normally get its value from the 75 degree column. But one end of the termination rating is unknown. Therefore we would have to use the 60 degree column.

The 60 degree column is only used for conductors rated 100A or less. (no matter the insulation value)
The 75 degree column is only used for conductors rated over 100A.( no matter the insulation value)

The above is what I have been taught.

If this is incorrect can you please clarify for me the right way to go about picking a wire from the table? And the specific scenarios in which you would use each column? Thanks.
 

·
Registered
36th year apprentice & Floor Sweeper
Joined
·
1,483 Posts
Sounds correct to me, but there are other rules that supersede the basic rules. Like rules for Romex, and tap rules.
 

·
Administrator
Retired EC
Joined
·
23,358 Posts
The 60C and 75C are only used when the temperature rating at the terminations are not known. For example you are working on an old panel and the rating of the panel isn't known. In this case you would use 60C for 100 amps or less or 1awg and smaller.

75C is used for larger than 100 amps or larger than #1 awg
 

·
Registered
Electrician
Joined
·
1,759 Posts
Just as Dennis stated. 75c column is perfectly fine for 100 amps or less if the wire and termination points are all known and your adjustments aren't to much. However 60c will be used for all nm cables(romex) final value but you can still use 90c for nm adjustments.
 

·
Administrator
Retired EC
Joined
·
23,358 Posts
Just as Dennis stated. 75c column is perfectly fine for 100 amps or less if the wire and termination points are all known and your adjustments aren't to much. However 60c will be used for all nm cables(romex) final value but you can still use 90c for nm adjustments.

Do you mean 100 amps or more?
 
1 - 5 of 5 Posts
Top