How do I get a 240V stinger leg down to 120V?

Question

This is and old system out dated electrical system. Well this is a 120/208v panel and the panel is pretty full. I have three spaces left, a-phase 120v, b-phase 120v, c-phase 240v. how do get the C-phase to 120V. for my swamp cooler?

Answer 1

You would need a transformer to do that. Another solution is to add a small sub panel so you have more breaker space. The panel you have is a high leg 120 configuration that was quite common 60 years ago. Call a qualified professional electrician to add a small sub panel and to tap 2 of the 120 legs and the neutral. Do not try to use the high leg.

Answer 2

If you're talking about 'center tapped delta' you can't

use that C phase for 120V.

If you've got a three phase panel, and are seeing 240V. Phase to Phase,

and 120V.  A-N, and B-N, that's what you've got.

If you're out of circuits, an electrician can give you a sub panel to

supply a few more. - Tell him what you've got.

Cheaper than a transformer.

Messing with this system is not a DIY project unless you know what you're doing.

It's not in most textbooks.

Answer 3

The best possibility is to evaluate the load on existing circuits and free up an additional 120 space, , as the only way to step down from the 208 is via transformer which in this instance is not a cost effective approach. Your swamp cooler quite possibly could be dual voltage and be rewired to run 208 as well. I bet you have a circuit that is very lightly loaded that could share an existing breaker location.

Answer 4

If you are in the US the only ABC phases are for 3 phase which is commercial. Since you have a- phase spare why not use it??