Jimmy7
Senior Member
- Location
- Boston, MA
- Occupation
- Electrician
I ran two 12-2 romex cables to a laundry area and I had to change over to emt to a 4" square to get into the room.
These are 120 volt circuits. I believe I have to derate, correct? This would be four current carrying conductors, so I would use 310.15(C)(1) which would be 80%. I then would use 310.16 90 degree column ( I have always been taught to use the 90 degree column. Where is that written?) Anyway, a #12 would be 30 amps at 90 degrees - 30 amps x 80% = 24 amps, so I can use 20 amp breakers, correct?
These are 120 volt circuits. I believe I have to derate, correct? This would be four current carrying conductors, so I would use 310.15(C)(1) which would be 80%. I then would use 310.16 90 degree column ( I have always been taught to use the 90 degree column. Where is that written?) Anyway, a #12 would be 30 amps at 90 degrees - 30 amps x 80% = 24 amps, so I can use 20 amp breakers, correct?