Changing Service from 240v 3ph Delta to 1ph 120/240v

[StreamlineGT]

I have a very large industrial building that has changed hands. The building used to be a manufacturing facility, very old, brick, 3 story factory. It has a very large 240 Delta 3ph service. The people that purchased the building is a non-profit, and has no need for the 3ph, and would get more use out of more 120v loads.

My question is this, what would really have to change in terms of wiring? The grounded "phase" used the neutral bar, and 3 phase loads use 2 pole breakers. Would all I have to do is look into changing 3ph loads to single phase? There are some HVAC equipment that would need to be addressed, but other than that, nothing. All the machinery has been removed.

Would it be in their best interest to have it changed? There are a "million" tiny transformers feeding small panels everywhere to get their 120v, and the available power is dwindling fast without adding more transformers and panels. The non-profit is an youth art organization, running stage lighting, audio, video, photo programs, etc.

Thanks for your input.

Brendon

 

[kwired]

Depending on total load you may be better off having supply changed to 120/208 then you can still use three phase panels that may be existing and can use 1.73 times ampacity vs single phase per conductor (125 amps of three phase can supply approximately same power as 200 amps single phase, 400 amps three phase equates to about 700 amps single phase. This can make a big difference on cost of conductors, raceways,switchgear, etc.

sorry I didn't read careful enough - appears you have corner grounded B phase and no 3 buss panels right? If so not much should need changed. just remember that you will now have less total capacity without the third phase.

 

[don_resqcapt19]

The only way to get more 120 would be to change the service or add more transformers. If the utility would supply you with a single phase service that is large enough for all of your loads that might be the easiest way, but many utilities won't supply large single phase services. If they won't supply a service that is large enough, you could install a 240 to 120/240 transformer after the service disconnect and use that to supply the existing distribution system. You would have to make sure that there are no 3 phase loads on the part of the system that you are supplying via the transformer.

 

[hillbilly1]

Some POCO's will give a cheaper KWH rate for single phase, I had a customer that had three phase available at the street, but wanted single phase because the per KW charge was less. Built a 1200 amp single phase service, the poco underestimated their load and blew the transformer out in a couple of months. They changed to a larger transformer, and it's been that way for about 25 years now. The store is out in the middle of nowhere, so they just moved all of the residental services to the other two phases to balance the load.