sizing the neutral conductor on 120/240V services
sizing the neutral conductor on 120/240V services
(OP)
What factors should be considered when sizing the neutral conductor on a single phase 120/240V service? A lot of utilities use a reduced neutral (ie Aluminum 4/0 for the two hot legs and a 2/0 neutral), but I understand harmonics from electronics can require a neutral at least as large as the hot legs. Anyone have any comments on this?
K2ofKeyLargo






RE: sizing the neutral conductor on 120/240V services
#2AL, 1/0 AL, and 4/0 AL. The 120/240 volts does not have as much problem with harmonics because the hot legs are 180 degree out of phase and the triplen harmonics cancel.
RE: sizing the neutral conductor on 120/240V services
WRT harmonics, as already pointed out, the triplens DO cancel.
So if the phase wires are 1/0, the neutral will be #2. If the phase wires are 3/0, the neutral will be 1/0.
After the utility/facility demarcation, the NEC or CEC (or OESC) applies.