Coppersmith
Senior Member
- Location
- Tampa, FL, USA
- Occupation
- Electrical Contractor
In dryer and range circuits, is the neutral considered a current carrying conductor for derating purposes?
In dryer and range circuits, is the neutral considered a current carrying conductor for derating purposes?
I agree, same appliance generally can be used on either system and neutral will be a CCC if supplied from a wye system.If it's from a 1Ø, 240 volt system then the neutral does not count as a CCC. If it's from a 3Ø, 208Y/120 volt system then it does count. Since you said 240 volts you're good.
If this is in the US of A, most dryers do. The motor, and computer is a 120vac load. The only load internal of the machine that is 240vac is the heater itself, which is typically around 5400 watts depending on brand. Some machines imported from overseas, such as Bosch or a lot of the 24 inch Apartment units, only use 240vac.Does your dryer have a 110 volts load?
Doesn't matter. As GoldDigger said above, any neutral current is current not being carried by a line conductor, so the neutral still need not be counted on 1ph.Seems to me if the dryer needs a neutral connected, then the neutral is a CCC. If the dryer does not have a neutral terminal, then the neutral remains unconnected and is not a CCC.
If dryer needs a neutral connected then yes it does carry current. OP's question AFAIK is whether it needs counted as a CCC when it comes to ampacity adjustment purposes. On a 120/240 singe phase system, it only carries unbalanced current between the ungrounded conductors. In a wye system with only two of the phase conductors as the circuit, it doesn't carry imbalance current and has to be counted as a CCC for ampacity adjustment reasons.Seems to me if the dryer needs a neutral connected, then the neutral is a CCC. If the dryer does not have a neutral terminal, then the neutral remains unconnected and is not a CCC.
You know us - we weren't asked for it.10 replies already and nobody has cited the code section.
You are correct of course. I had a complete mental lapse.Doesn't matter. As GoldDigger said above, any neutral current is current not being carried by a line conductor, so the neutral still need not be counted on 1ph.
Seems to me if the dryer needs a neutral connected, then the neutral is a CCC. If the dryer does not have a neutral terminal, then the neutral remains unconnected and is not a CCC.
You are correct of course. I had a complete mental lapse.
And would still have same heating effects in a raceway or cable. L1 carries heater current plus motor current. L2 only carries heater current. N only carries motor current. (timer is sort of negligible amount of current and can be ignored here).But then you would be sending current down the noddle and not the other hot leg.
And would still have same heating effects in a raceway or cable. L1 carries heater current plus motor current. L2 only carries heater current. N only carries motor current. (timer is sort of negligible amount of current and can be ignored here).
And is no different than a MWBC with similar unbalanced current. L2 runs cooler, N runs a little warmer. Net effect of all three conductors in the raceway or cable is about the same - close enough NEC doesn't think we need to count all three as CCC's for ampacity adjustment reasons. If it were two conductors plus neutral of a wye system however, that current on the N is not unbalance current like it is with split single phase system. Maybe for a dryer it sort of wouldn't really make that much difference, but NEC doesn't single out this sort of thing as an exception to the rule.Yes, but because that current is going down N and not L2, L2 runs cooler allowing for N to add heat without everything in the conduit getting too hot.
And is no different than a MWBC with similar unbalanced current. L2 runs cooler, N runs a little warmer. Net effect of all three conductors in the raceway or cable is about the same - close enough NEC doesn't think we need to count all three as CCC's for ampacity adjustment reasons. If it were two conductors plus neutral of a wye system however, that current on the N is not unbalance current like it is with split single phase system. Maybe for a dryer it sort of wouldn't really make that much difference, but NEC doesn't single out this sort of thing as an exception to the rule.