ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Solar PV Wiring Errors
by renosteinke - 03/02/24 08:12 PM
Do You Wrap Your Receptacles?
by gfretwell - 02/20/24 10:48 PM
Cable Chase Code Requirement
by renosteinke - 02/16/24 07:00 PM
Do we need grounding?
by gfretwell - 02/16/24 10:37 AM
Cordless Tools: The Obvious Question
by gfretwell - 02/08/24 07:28 AM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
0 members (), 23 guests, and 32 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#75226 02/17/07 07:44 PM
Joined: Dec 2004
Posts: 78
C
Cinner Offline OP
Member
If you are derating wire due to conduit fill(example - 4/0 derated to 3/0 ampacity) should the circuit breaker be sized to protect the new derated amapacity of the 4/0?

Joined: Feb 2003
Posts: 231
R
Member
No, stay with circuit breaker size and just increase the awg of the wire when you have to derate.




[This message has been edited by RobbieD (edited 02-17-2007).]

Joined: Mar 2005
Posts: 1,213
S
Member
The derated ampacity cannot exceed the overcurrent protection. So, you either have to downsize the breaker or upsize the cable. Normally, it's the latter since the original breaker size is chosen for a reason, but using a smaller breaker is OK if circumstances allow.

Joined: May 2005
Posts: 984
Likes: 1
G
Member
Huh?
Are you saying that I can't feed a 15 amp load with a 20 amp breaker using #8 wire???
...or did I read your post wrong?


Ghost307

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5