mstrlucky74
Senior Member
- Location
- NJ
Have 120/208 3P 4W 100A being fed from 3P 40A breaker. One drawing asking for 4#6 & another drawing asking for 4#8’s. Conductors should be sized off 40A breakers, correct? So #8’s ok.
Wire Size
- Thread starter mstrlucky74
- Start date
- Status
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
As long as there are no adjustments needed that reduce #8 to less than 40 amps, yes #8 is minimum size needed here per NEC.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Long distance may merit #6 but as kwired stated the #8 is compliant. I would definitely ask the engineer and get this corrected on the drawings
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
It might also be a future consideration; ie 40 A now with a possibility of bumping to 60A later without having to pull new conductors.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Why not install the 60 amp breaker now if that is the case? Especially if is three pole or a 277/480 volt breaker. Your double pole plug on breakers 60 amp and below are usually pretty inexpensive and there is a possibility you put in a 40 now, though I'd still normally put in the 60 now if that was the reason.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Either conductor size is code compliant I would use the #8 unless there is a voltage drop concern.
- Status