Dock Wiring Advice

Kevin77May 10, 2011


Looking for some advice on running wire to our pier. The distance will be around 425' with about 175' in the ground and 250' under the pier walkway. I mainly want to be able to install a few lights at the end and be able to charge some batteries. I want to make sure I run enough power for a future boat lift (will probably have 1-1.5HP motor) and a gazebo which might have a light and fan.

In addition, I'd really like to add some lights to the long pier walkway. I'd prefer to be able to turn them on/off from a switch inside the house. The guys building my pier are not licensed electricians but have done quite a bit of wiring building docks for a long time. Here is what they tell me. Please let me know if this makes sense.

Basically they want to run a size 10 wire inside 1/2" PVC conduit all the way to the end of the pier. They say this should be enough to handle future boat lift expansion etc. For the walkway lights to be able to be operated from inside the house, they tell me we should run a second line (size 12), in its own conduit and then basically just tie the lights into this wire. If we put a light every 8 feet on one side only we are potentially looking at about 30-35 lights.

I welcome any and all input!

Thank you, Kevin

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Ron Natalie

That seems like an entirely reasonable way to do it. That's a rather long run, so the larger wiring is probably advisable. With the 1.5HP lift you will need it as well. Actually, my lift is solar powered.

You might be able to direct bury things but you'll have to trench down lower.

    Bookmark   May 10, 2011 at 8:25AM
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Thanks for the input! I think the lift motor will draw about 10 amps at 230V and 20 amps at 115V. The thing that concerns me most is the wire size and picking the right one, plus trying to get wire inside the house for the light switch.

    Bookmark   May 10, 2011 at 8:39AM
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My best advice for wiring to and on a dock is to hire a licensed electrician. DO NOT allow the dock builders to wire this up.

    Bookmark   May 10, 2011 at 12:53PM
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"I think the lift motor will draw about 10 amps at 230V and 20 amps at 115V."

Depending on the type of motor the starting surge can be significantly higher than the runing current.

!00% higher (double the running current) is not all that uncommon) especially for a motor that must start under load.

If the voltage sags during start up the motor will take longer to start, may not even start, and will run hotter with a shorter life.

You need to identify some typical lifts and determine there starting surge needs, then select the wire size based on that.

You may need to deliver 30 or 40 amps during starting without sagging the voltage more than 3-5%.

    Bookmark   May 10, 2011 at 3:59PM
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