480 volt singe phase system changeover

[Mark huybrecht]

I have a 480 volt single phase system at an auto dealer that uses a single pole 240 volt line lead and a neutral to power their hoists and air compressors.The service is being changed to 240/120 volt single phase.How do I wire the hoists with 2 pole,240 volt,single phase?The motors are 208/230 volt only.Thank you.

 

[ActionDave]

That's a weird system for a building. How are the 120V loads handled? Transformers or is there another service?

The motors won't care is the voltage is line to line or line to ground as long as it is 240V.

 

[mbrooke]

I have a 480 volt single phase system at an auto dealer that uses a single pole 240 volt line lead and a neutral to power their hoists and air compressors.The service is being changed to 240/120 volt single phase.How do I wire the hoists with 2 pole,240 volt,single phase?The motors are 208/230 volt only.Thank you.

Simply place them on a double pole breaker. Make sure the wire color is other than grey or white, if its part of a cable assembly you can remark them with tape. I would also check that no inadvertent ground faults exist on the neutral going to the equipment. If a ground fault took place at any point over the years it would've gone unnoticed, until it becomes a hot leg.

That's a weird system for a building. How are the 120V loads handled? Transformers or is there another service?

The motors won't care is the voltage is line to line or line to ground as long as it is 240V.

I would venture to say its in place for the exterior light poles. If the lot is large enough I can see 480 volts adding major wire savings especially if voltage drop was a concern. Bringing in 480 would then look like a smart idea.

FWIW, 480 volt single phase, corner ground delta and 3 wire Y, is often used on DOT lighting projects.

 

[Mark huybrecht]

Thanks for the info,I really appreciate your help.The 120 volt loads are fed from a sub panel,stepped down with a transformer.Thanks again!