Size/type of wire for driveway lighting

[s219]

We have a 600 foot driveway at our new place, and I would like to light it. I have a bunch of 50W and 70W high pressure sodium lights from our old house that I can reuse (3-4 lights should be sufficient, spaced out every 150-200 feet). I figured I would trench to run a main cable, then use conduit to run up trees to the lights.

Anybody have suggestions for the type of wire I should use? Solid? Stranded? I can run conduit in the trench or use a direct bury wire if there is one. I'd assume two 50W lights and two 70W lights would be the max load.

thanks,
219

 

[Western]

I cant answer it for you, but I can give you a couple of ideas.

I would go, or call and electrical supply, tell them what your doing and they will let you know what you will need. Thats what I do when I need the correct wire for an underground run, they know, since they deal with it on a daily basis. (not talking about Lowes or HD) I would double the estimate on the power needed, just in-case you end up adding more lights, you will have enough underground to expand.

I do allot of work on big parking lots (walmart size:laughing but I cant say where The large sodium parking light fixtures have long runs, they use individual wires in conduit underground. Usually (from what I've seen) it's Red,Black and Green about 10 gauge.

Wish I could be of more help, I know Most guy's dont like to comment on electric since it is a dangerous topic.

 

[BrandonR]

At 600' you'll need to use heavier wire than if it was a short run.

If you want to have a full 15 amps available at the end of the wire with acceptable voltage drop you'd need #2 copper that's going to be pretty costly. If however you only ever intend to power the 170watts of lights that's only 1-2 amps and you drop down to #10 copper for 120V lights or #14 for 240V (you didn't say whether the lights are 120v or 240V). If you get tempted to add an outlet out at the end of the driveway understand you'll get awful voltage drop if you run anything less than the #2 , even a small 5 amp load (electric drill for example) will cause a drop of 18v (down to 100v or so) with 14ga making it useless for that. Considering the cost of the wire if your lights aren't already 240v units you may be better off not re-using them and purchasing 240v units so you can cut the cost on your wire.

 

[PILOON]

I also have a fairly long driveway.
You might consider doing what I did. I used #12 wire (outdoor bury grade) and installed motion detector flood fixtures into which I used compact fluorescent floods.
The installation is in place for some 4-5 yrs without any problems.
The CF floods are slower to light up but still do a great job. The plus side is I have not needed to change in all the time they have been operating.
Cost of operating is minimal (CF's) and they certainly do the job as well as previous 250w halogens.
Down side is on windy days moving branches sets off the lighting, but hey, CF cost peanuts to run.
The power demand on CF's is so low I could probably have used 14 gauge but I had the 12.

 

[s219]

Thanks guys, appreciate the advice.

 

[JDgreen227]

Thanks guys, appreciate the advice.

If your lights are 120 volt and you don't plan to add anything else such as an outlet at the end of the run, I am thinking 12-2 UF will work fine. The UF type is direct bury, no conduit needed. I use the high pressure sodium lights on my outbuildings and am very happy with the bulb life and low energy usage. Some people don't care for the yellowish tint of the bulbs but I don't care about that. My spec sheet for my 120 volt sodiums says the amp draw is .625 amps for the 50 watt and .90 amps for the 70 watt.