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3 Phase Service Choice?

silencerman

Plastic
Joined
Nov 7, 2011
Location
Pennsylvania U.S.A.
My shop once had 240 high leg delta in it which worked well but at some point prior to me having it the service was disconnected. I'm trying to get service installed but the electric company won't do high leg delta anymore. my only real choices are 120/208 and 277/480. it may seem like a no brainer but i have some equipment that runs on 480v that uses a transformer to step up from 240.
Should i get 480 and run through a transformer all the time or get 208 and shop for a new transformer for the 480 stuff?
 
Depends on your load sizes IMO. If you dont have anything over about 15-20hp, then 208 will probably be cheaper. Especially if you can kill power to the step up transformer when not in use.

480 is nice for larger loads, as the wire sizes are so much smaller. Breakers and disconnects usually cost more, and if you have a step down transformer humming all the time just to power your lights and several smaller machines, it's going to add a few bucks to the electric bill every month.

I have a 40kva step down that is always on and the minimum bill is about $50 more than before I hooked it up.
 
Consider the cost of running the transformer. Specifically, only energizing the transformer when running those 480 tools, vs leaving a transformer on all the time to keep computers and the office fridge powered on.

An acquaintance of mine has shifted to running his cabinet shop part time as he heads into retirement. In trying to see why his electric bill was so high when doing virtually no work, he started killing the transformer on nights and weekends, and found that it cut over 200 bucks from the bill per month. It's a bit of a pain to have to restart computers every morning, but what he's really annoyed about is the 20 years that he's been running that thing all night and weekend.
 
208 service and transform anything up to 480 that isn't field rewireable. 480 is ideal for commercial environments with tons of equipment and relatively low concern for idle costs. You will spend more on the idle costs than the one or two step up transformers to power your current 480 stuff.

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