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I need 14 amps at my boat house to run a boat lift on 120v. The boat house is approximately 200' from main panel. I can run conduit and #8 wire and make it work with no problem, but I will need to buy all materials.

I have some 3 conductor #10 w/ground. Can I run this wire off a 30 amp double pole breaker and set a 2 circuit 30amp outdoor panel and pull 1 - 20amp circuit with at least 14 amps for the lift and another for just lights?

Will I have the power I need by doing this?

  • Ecnerwal has most of it covered. We can help some more if we can have the motor size. If the motor/s want a bunch of power, they are going to pull the voltage down, the current draw up, and over the length of wire, it will trip mid-lift or the motor will shut itself off for thermal overload. Modern aluminium is not the Al of 20 years ago. Al makes sense. Quick look at home depot a foot of 2/2/2/4 Al URD is less than 10/3 copper UF. A wise man once said, never max out your current on install, the future will always find a need for more. His son said, dad run 1/2 inch pipe for internet or phone. – Some Guy Mar 25 '15 at 14:20
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    IF the boatlift can be reconfigured to run on 240V (at 7 amps) everything gets easier. – Ecnerwal Mar 25 '15 at 15:26
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Maybe. Depends how sensitive the boat lift is to supply voltage - #10 copper at 14 amps for 200 feet is about 5.8% drop (or 7 volts) - nearly double what is normally designed for. But given 120V at the head end, that's still 113 volts, and many items are perfectly happy with 110-125V.

http://www.electrician2.com/calculators/vd_calculator.html

Is the 3 conductor #10 OUTDOOR wire? If it's indoor Romex, it cannot be used outside, even in conduit - the insulation is not rated for water, and all conduits outdoors are assumed to be wet (and the assumption is usually right.)

If you are buying wire, look at #4 or #6 Aluminum - it may well be a LOT cheaper than #6 or #8 copper, even if you have to buy conduit one size larger.

http://www.electrician2.com/calculators/rf_calculator.html

(not affiliated in any way, just one of the more useful/less-spammy sources of VD & Fill calculators - there are many others.)

When you are trenching for the power, consider dropping another conduit (even 1/2" could work) in case you decide later that you'd like WiFi at the dock area. No need to run wire now, but you'll kick yourself later if you don't, and it won't cost much to add.

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