Hi leg delta (revisited)

[ubbogus2]

Down here in TX the 3 phase-to-phase is 240VAC. The building we are in has phase C as the hi leg (213VAC measured). We have half the breaker panel using A & B to wire 120 to offices and the other half A & B for 240 welders and such. As it is the load is severely unbalanced as all the C positions are vacant. The question is - can I use double breakers across B & C or C & A for 240VAC usage?
Thanks,
John in Spring, TX

 

[Lectricbota]

Down here in TX the 3 phase-to-phase is 240VAC. The building we are in has phase C as the hi leg (213VAC measured). We have half the breaker panel using A & B to wire 120 to offices and the other half A & B for 240 welders and such. As it is the load is severely unbalanced as all the C positions are vacant. The question is - can I use double breakers across B & C or C & A for 240VAC usage? Thanks,John in Spring, TX

Yes you can---just make sure to use 240 volt straight rated circuit breakers, and not the slash rated 120/240 breakers.

 

[texie]

Yes, you can do this, and as lectricbota indicated you must use fully rated breakers, not slash rated IE 120/240. Couple of caveats though. Don't do this to any load that also requires a neutral such as a dryer or similar. Also keep in mind that most 240/120 3 phase PoCo transformer banks are not built for a balanced load as most are built as open delta with just 2 transformers. Usually the 2nd transformer is smaller and provided just for minimal 3 phase loads and they expect you to have most of your single phase load on the larger transformer.