neutral derating
- Thread starter jumathum
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Are you asking about the feeder to the panel?
- Location
- Illinois
- Occupation
- retired electrician
If you are using a neutral with 2 ungrounded conductors of a 3 phase wye system, it is always a current carrying conductor. If you are using it with all 3 ungrounded conductors it is a current carrying conductor only if the majority of the load is non-linear.
ohmhead
Senior Member
- Location
- ORLANDO FLA
Well i maybe incorrect please correct me , but 3 phase its the unbalanced load on that neutral of the 3 legs meaning it has to be counted and that is feeder or branch circuit if A B C is connected to a neutral then it has current flow thur it which effects temp in conduit . comments ? best to ya
- Location
- New Jersey
- Occupation
- Journeyman Electrician
A 3 phase, 4 wire Wye feeder to a panel would be 3 CCC's unless the majority of the load on that feeder were non-linear. IMO that's not very likely.
The neutral carries the imbalance of three possible line currents. For the neutral to carry current, at least one of three line conductors has to be conducting more or less current than the other two (consider a three-wire circuit as being a four-wire with one line turned off). The heat generated by current through the neutral conductor is offset by the heat not being generated on the lesser conducting lines... and vice-versa. All said and done, a 3?, 4W circuit cannot generate more heat than the maximum current through just three of its conductors, except of course, when most of its load is non-linear.
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