2500 foot extension cord?

[Shiftman]

All,

I am looking to electrify my in-forest pump house. This will increase reliability and production as I currently run of a generator. Current draw in the pump house is 22 amps at 240V. (5hp vacuum and 2hp in pumps)

I can either run a 240V cable or 600V cable with a transformer at each end. Has anyone heard of this being done before? Any suggestions? Looking to get this done for $5k.

Thanks

[Biz]

I don't have any experience running AC power for that distance, but a quick look at wiring tables for resistive losses says if running 240 volts you are going to need really heavy gauge wire, or double up on smaller, either of which which is going to be very expensive. At 22 amps, 240 volts, assuming a 10 volt loss in the wiring (5000' round trip) you would need at least 0 gauge wire or double up on 4 gauge. The additional AC losses might mean you should upsize even further. Even then I don't know if it will work for motors due to startup currents. Gut feel is a transformer at each end would be cheaper since you could use wiring half the size or a little less, but an expert should weigh in. Interesting problem though, let us know what you find out

Dave

[maple flats]

you can't just figure the running amps, you need the start surge amps. 240V at that distance will cost more than the $5,000 limit, but using step up and step down transformers you might make it. See how high you can step up and down first, then use a voltage drop calculator for the right size wire. If you can go higher than 600V the wire will be less costly. That is why the utilities run high voltages roadside and much higher on high tension lines. You will need to know the surge amps when the pumps are cold and try to sequence the on cycle. You will do best if the 5 HP kicks in a few seconds before the 2 HP.

[Tmeeeh]

We ended up running a 2" vacuum line 2,000' to the 3/4 hp electric releaser and pumping the sap back with a two horse 3 phase pump controlled by a Variable Frequency Drive. The VFD soft starts the pump nearly eliminating the start surge. The 2" vacuum line is less expensive than the wire that would have been needed if the vacuum pump was at the far end of the wire.

[Bricklayer]

You can get a pretty nice generator for less then $5000. Even a quiet propane fired generator would be less then $5000. Sounds like a lot of money to get power. I went to a saw mill a couple weeks ago and it was probley the same distance out in the bush. He had one of those Back up generators designed for houses and it ran off 2 big propane tanks 400 pounders. But what he did was run the low voltage wire in a conduit back to his garage at his house. This way he can turn the generator on and off without having to go out there. I didn't ask hike he long the propane lasted. But I would assume that 800 lbs of propane or even 400 lbs would almost last a sugaring season. If it's just running a vacuum pump or 2 the generator won't be running full throttle. And you have propane at your shack for heat at night for the RO.

[Hubbert]

I did almost the exact thing this past year. Cost however is an issue. I went to 600 volts then 2800 feet and back down to 240 with 30 amps. It was very expensive with the cable at $7,500. I use the electricity to run lights, heat and two piston pumps to transfer the sap 5400 feet to my sugarhouse. The vacuum pump itself remained at the road where the hydro comes from and works the remote release via a 3 inch air line. I can talk to you more about it at the summer tour if you wish.

Bill Hubbert

Sundridge

[Shiftman]

Thanks all for the input. I'm currently taking to a few electricians and the idea is achievable. Most motors can handle a 10% voltage drop and with a 600v transformer it may be achievable for under 5k. To save costs I would ground the pump house on location and run a 2 conductor wire down. I'll let you know where the final design stands.

Bill, I look forward to talking about it at the maple tour. Thanks

[BAP]

Be careful about the voltage drop. Even though the motors can take it, they run hotter and will burn out much quicker costing money.

[Maple Man 85]

If you use aluminum 2 gauge it is roughly 1.06 a foot and more economical than copper roughly somewhere in between you are going to need a capacitor of some sort to compensate for the voltage drop.