Voltage drop solution

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ggibbs

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I need to run power to an existing structure (barn) on my property. The problem is that it's about 1700' from my service to the barn. Total electrical load will be very small; likely not over 10 amps and realistcally more like 5 amps or so (just a few 60w incadescent light bulbs).Extending the utility companies poles to the barn would run close to $10,000, so that's out.
According to my voltage drop calculation a 5 amp load would require #2 copper wire (also quite expensive).
I had an idea to aquire two 240/480 to 120/240 stepdown transformers, hook one up at my service backwards , stepping the voltage up from 120/240 to 240/480, then running the 1700' circuit and stepping it back down to 120/240 with the second transformer. If this would work, it would decrease my required wire size for a 5 a load from #2 to #8 thus creating a substantial savings in wire costs.
Will it work? Any comments or suggestions appreciated!!
 
Re: Voltage drop solution

you could run aluminum, 4/0/ 4/0 2/0 is a very common size so the price will be less. I helped install a circuit for a small pump at a golf course where it was 2,000 feet and we installed a step up and step down transformer. we used 12 AWG copper in 3/4" pvc, look at using aluminum, 8 wag is the smallest I would use
 
Re: Voltage drop solution

Yes, I think that would work (when you say you will "connect one to the service", I assume you mean a branch circuit with a 15 or 20A breaker.).

But if you ran 2 hot wires from different phases, and one neutral and ground, you could put half the lights on each phase. For #8 wire, I calculate the voltage drop for 10 amps at 25.5 volts. That's only about 10% for 240V. Not very efficient, but it should be ok for a few lights.

If you live in a warm area, I would consider fluorescent lights.

STeve
 
Re: Voltage drop solution

In theory you would be able to run your transformers as you described. However, check with your transformer manufacturer some of them may have concerns of backfeeding small tranformers.

Some other areas of concern would be:
1) The inrush on the "backfeed" transformer may be very high and therefore requiring oversized overcurrent protection. This oversizing may require an overcurrent device on the secondary.
2) You will need to provide overcurrent protection for the 480V primary transformer. If this is kept to 125% it can serve as the secondary protection required by condition #1.
 
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