3 Phase on the Farm.....Question

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Booner

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I recently had the local electrical co-op run 480/277 to my farm. (As a hobby I tinker with old machine tools and I wanted the 3 phase for it.)

So hear I sit with two services....A single phase and a 3 phase..including two(2) bills each month. So I am considering supplying the house from this 3 phase service and eliminating the single phase service completely.
I was thinking of purchasing a 480 delta to 208/120 transformer to feed a 208 3 phase panel and then feeding the house off of it.

I am debating what size transformer to purchase. ( I have about 200 amps of single phase load.)

I am planning on doing this work myself........ You gotta love the county.....unqualified electricians and volunteer fire departments.
 
Sorry, but this forum is not allowed to give advice to DIY'ers. The best we can advise is to hire a properly-licensed electrician.
 
I understand/repect your response....I was actually joking about the DIY/Volunteer fire department.


I am researching the purchasing of the needed items. I want to understand my options before I bring in an electrician.

Great site.....I just found it and have been reading on it for hours. Wife is upset....
 
Is your current single phase service 240/120V or 208/120V? If its 240, can you live with those 240 items only getting 208V? Things like water heaters, electric ranges, clothes dryers, and 240V heating will be slower and produce less heat. Some 230V motors or pumps may not be happy.

What size single phase transformer do you have now, and does it apear to be adequate? If so, that should be a clue as to the size of the new one unless you're adding more load for new 208V 3 phase toys.

The tougher question for me would be 208/120 wye seconday or 240/120 delta secondary or 240/120 single phase secondary. I don't know enough about transformers to know if a 240/120 delta secondary is possible given a 480/277 wye primary. If you have three phase 208V tools, then you've got some conflicting requirements. Its going to take a lot of $5/month meter charges to pay for a 25/37.5/50 KVA transformer.
 
Simply use a 480V single phase (2 phases of the three phase service) and step it down to 120/240V to match the existing service.
There would be no advantge to use a 208Y/120V secondary unless you are also needing three pahse at the 208V level as well.

As elluded to by Mark, the payback on this installation to develop low voltage off your 480V service will probably be at least 15 years, if all you are trying to do is elminate the $5 meter charge.

As also stated, this installation is much more than should ever be attempted by a DIY.
 
Booner -

Kingpb's suggestion is good. But you may want to go a little further. Depending on your outbuildings, you may want to go with a couple of 1ph, 240V xfmrs fed from different 480 phases. This could cut down on your house lights blinking when starting bigger machinery loads, like table saws and such.

I think this is closer to an industrial electrician's skill set than a residential electrician's skill set. Hopefully you have someone local that can do it all.

As also stated, this installation is much more than should ever be attempted by a DIY.
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I certainly wouldn't suggest a DIY, but I suspect you already know your own capabilities and limitations.


whoops -hit the submit too soon
 
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