How many #12 ccc in a conduit add still terminate on a 20 amp breaker.

Status
Not open for further replies.

nolondant

Member
I have 4 # 12 THHN phase conductors each has a netural conductor, these conductors are dedicated to computers. After ampacity adjustment factors have been applied to these conductors, will I still be able to terminate these conductors on a 20 amp breaker.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I have 4 # 12 THHN phase conductors each has a netural conductor, these conductors are dedicated to computers. After ampacity adjustment factors have been applied to these conductors, will I still be able to terminate these conductors on a 20 amp breaker.

What do you think. Let's see a little math then we will help you out.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
The answer has appeared here numerous times. Like Dennis asked, what do you think the answer is?

Welcome to the Forum. :)
 

480sparky

Senior Member
Location
Iowegia
>3, <100.
themot-roflolmao.gif
 

nolondant

Member
6 CCC is all you can have because of the 75 degree terminals on the breaker. 7 CCC would only be good for 17.5 amps after derating. You would not be able to terminate a conductor rated for 17.5 amps on a 20 amp breaker. The contractor wanted a more professional opinion. Please help.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
6 CCC is all you can have because of the 75 degree terminals on the breaker. 7 CCC would only be good for 17.5 amps after derating. You would not be able to terminate a conductor rated for 17.5 amps on a 20 amp breaker. The contractor wanted a more professional opinion. Please help.
Look at T310.15(B)(2). You can have 9 conductors with a 70% reduction. You can use the 90C table for derating. 12 @ 90C is 30 amps. 70% of 30= 21 amps.
 
Status
Not open for further replies.
Top