dana1028
Senior Member
- Location
- San Francisco Bay area
Scenario: after derating, some #12 THHN conductors have an ampacity rating of 17.5A
What is the maximum OCPD permitted?
No, this is not a test question. My understanding is the conductors cannot be protected above their [derated] ampacity...which would be a 15A breaker.
But I thought I read a comment here from someone [it's been awhile] indicating you could use the 'next higher breaker' rule [240.4(B)] and thus put a 20A breaker on these conductors.
Which is it? Thanx
What is the maximum OCPD permitted?
No, this is not a test question. My understanding is the conductors cannot be protected above their [derated] ampacity...which would be a 15A breaker.
But I thought I read a comment here from someone [it's been awhile] indicating you could use the 'next higher breaker' rule [240.4(B)] and thus put a 20A breaker on these conductors.
Which is it? Thanx