Two source of power to a Fan Powered Box

[montauk1989]

We've got a problem on a project with a 480V source that has no neutral. The fan powered boxes required 480V 3 phase 4 wire with a neutral. They need 480V 3 phase for the electric heaters and 277V for the fan motors. There's a lighting panel on the floor without enough capacity to supply the fan powered boxes. Can we provide two disconnects one 480V and 277V at each fan powered box if they're properly labeled? I think we did something similar quite a few years ago. The manufacturer refuses to help. Another option would be a single phase transformer downstream of the 480V disconnect for a 277V circuit for the fan but we're having trouble finding a 750Watt 480-277V transformer.
Thanks

 

[retirede]

You can probably find a 480 delta to wye transformer more easily.

 

[kwired]

Limiting yourself to items that are more likely readily available, you are probably stuck with a three phase transformer with wye secondary, or 480x240 single phase plus buck boost to get to 277 volts.

480x 277 is probably going to be something custom made for you, and will be a wait for it to be made plus is likely to cost more then a stocked item of otherwise similar materials and construction.