NEC article 220.82

[Mostafa]

article 220.82 says that the optional method applies to a dwelling unit having the total connected load servedby a single 120/240-volt or 208Y/120-volt set of 3-wire service or feeder conductors with an ampacity of 100or greater.

does it mean that i cannot use the optional method for a dwelling unit supplied by a three phase - 4 wires feeder ? or it is applicable also in this case.

 

[Dennis Alwon]

The section does not say that 3 phase is allowed however you can use the optional to each unit which I assume is single phase just not for the service

 

[Mostafa]

Thanks.

the problem i has is to apply the optional method in my design and the unit is fed through a three phase - 4 wires supply. i would say it is against the article.