Sub panel

[D-Nice]

I am a residential man so I don't work with 3-phase and haven't in 4 years. It's a 120/240 high leg system and I need to install a sub panel. Can I come off of the two "normal legs" and install a 1-phase 3-wire sub?

 

[rrc14]

Sure, I don't see why you couldn't.

 

[Dennis Alwon]

I am a residential man so I don't work with 3-phase and haven't in 4 years. It's a 120/240 high leg system and I need to install a sub panel. Can I come off of the two "normal legs" and install a 1-phase 3-wire sub?

Yes .

 

[dnem]

I am a residential man so I don't work with 3-phase and haven't in 4 years. It's a 120/240 high leg system and I need to install a sub panel. Can I come off of the two "normal legs" and install a 1-phase 3-wire sub?

Just keep in mind that you can't load up the transformer to its full kva on just 2 legs. . The rated kva is the result of multiplying I x E x 1.732. . It's that 1.732 that will get you in trouble if you try to load that full kva on just 2 legs.

 

[LarryFine]

I am a residential man so I don't work with 3-phase and haven't in 4 years. It's a 120/240 high leg system and I need to install a sub panel. Can I come off of the two "normal legs" and install a 1-phase 3-wire sub?

As above, yes. The two 120v lines an the neutral, without the high leg, are exactly, and I mean exactly, the same thing as a 120/240v 1-phase service.

In fact, the high leg service started out as a 3-phase conversion to an existing single-phase system. The open Delta merely adds a single transformer to one.

 

[charlie]

If it is an open delta, 1? load goes on to the transformer with the center tap ground at 100% and no load goes on the high leg transformer.

If it is a closed delta, two thirds of the load goes on that transformer while one third goes on each or the transformers that go to the high phase (yes, I know that that adds up to four thirds). :smile: