Two phase (legs) on 3 phase panel

[lakee911]

Hi all,

I recently came across a situation where a 2-phase feed (120/208 meaning L1, L2, N) is used to feel a 3-phase 208/120 panelboard.

Other than being a little goofy, is there any reason why this isn't allowed?

Should the third phase be kept empty (meaning every 3rd breaker is unused) or can it be tied over to phase 1 or phase 2?

Thx,
Jason

 

[lakee911]

Anyone? I think this might have been discussed before, but I can't find it while searching... anyone have a link? Thx

 

[Jim W in Tampa]

nothing wrong with it other than was a waste of a 3 phase panel

 

[zbang]

I'm sure it's been discussed before, but calling it "2-phase" isn't correct. It's two legs of a 3-phase feed. Real 2-phase would have four hot leads. Do not use the empty bus, that makes it too easy to overload the neutral,

 

[lakee911]

I'm sure it's been discussed before, but calling it "2-phase" isn't correct. It's two legs of a 3-phase feed.

You're right ... I usually correct people on that myself. I don't know how I let that slip.

Real 2-phase would have four hot leads.

Really? Why wouldn't/couldn't it have three hot leads?

Do not use the empty bus, that makes it too easy to overload the neutral.

With a full size neutral, I don't have that concern, but it would make balancing the two legs tough. Thanks.