Can you apply 220.82 optional method for single phase 120/240V 1ph 3-wire high leg delta


Senior Member
I agree with the others.

Other than the Elevator (which would be fed from a separately metered House Panel), water heaters and condensing units are probably the only strictly 240v loads that could safely use the wild leg anyway.

Not worth the risk or the expense of extending the 120/240v 3ph delta to the apartment panels just for those.

You would also loose a lot of space in a 3 phase tenant panel in circumstances like this just trying to avoid the wild leg on the circuits that couldn't utilize it.



Electrical Designer
Thank you guys very much for the good ideas and learning!!! The 120/240V 3-wire service indicate the common 120/240V single phase service 3wire service, where voltage between hot lines is 240V, voltage between hot line and neutral is 120V. There is no 240Y/120V electrical system. The 208Y/120V 3-wire feeder is "A-B-N","A-C-N" or "B-C-N" from 208Y/120V 3ph 4wire system. The "A-B-N" feeder from 120/240V 3ph 4wire delta is not 120/240V single phase 3 wire service, since the voltage between B-N is 208V.

I won't take risk to bring "A-B-N" to units. Will bring "A-C-N" to units and 120/240V 3ph 4wire delta for house.