Using existing 12 volt source to power string of christmas lights

spencer_electricianNovember 24, 2008

A homes association had me bid installing an outdoor outlet on each side of a street to plug in Christmas lights on the neighborhood signs. There is an outdoor panel 150 feet away for a sprinkler timer outlet. My cost to trench 150 feet to the 1st outlet and horizontal bore under the street to the 2nd outlet came to $4500. So at $2250 an outlet, they got to thinking of alternatives :) At the panel there is a landscape lighting transformer which powers a 20 watt light on each side of the street. So we got to thinking of if there is any way possible to power a few Christmas lights with the source.

I told them that with a single 12/2 feed running 250 feet, the two existing lights is about all you can expect with that kind of voltage drop. I found online many strands of mini lights for 12 volt use, one 26 feet long strand probably uses 20 to 30 watts of power. So I told the idea to the guy from the city and he liked it. They only need to string a set a lights across a 20 feet long sign. Then the kicker, they want c5 bulbs and not mini lights. So are they out of luck without doing it right and installing REAL wiring? Or does such a thing exist, 12 volt c5 bulbs (or anything with a candelabra base) Perhaps something led or rope light (found they still use 2.5 watts per foot). I think using the landscape light feed is a rigged installation but maybe if it is the only way the budget allows, it is worth looking into. They would need a yearly contract to hang the special 12 volt lights because it's not like x-mas installers would understand the installation.

Just thought I would see if one of you has a great idea before I tell them they're out of luck.

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What about a small solar panel and battery?

    Bookmark   November 24, 2008 at 10:00PM
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Well that's similar to already having 12 volt power present, problem is getting lights that are compatible with 12 volts/ restrictions of 250 feet of wire.

    Bookmark   November 24, 2008 at 10:19PM
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Why don't they just buy a small Honda and hide it in someones back yard?

    Bookmark   November 25, 2008 at 9:08AM
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tell them they make battery powered lights. some use AA, some use 9v. they can then go change the batteries eveyr couple days.

    Bookmark   November 25, 2008 at 10:09AM
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Action Lighting has C6, C7, and C9 LED christmas strings, but 110volt. They use very low power, i.e. 25 lamps consumes 4.8 watts. SO you could put an inverter at the end of the 12v line to bump back up to 110 volt. This is sort of backwards, but it will work for your application.

Here is a link that might be useful: 25-lamp LED string

    Bookmark   November 25, 2008 at 1:57PM
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How firm are they about using C5 lights? You can find 12V LED Christmas lights if you do a Google search, but I didn't find any in the C5 size. I think some type of LED lights would be your best bet due to their lower power consumption. As another alternative, it is possible to re-wire a 120V LED light string to run on 12V. I don't think this is a practical solution in your case, but the link below tells how in case you're interested.

Here is a link that might be useful: Battery Christmas Lights

    Bookmark   November 25, 2008 at 2:43PM
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They need these solar power lights. Has a built in solar panel and supposedly runs for 3 mights on one days charging.
solar LED Lights

    Bookmark   November 25, 2008 at 7:11PM
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Remember that 1 watt at 12 volts is 0.0833 amps. 1 watt at 120 volts is 0.00833 amps. For a given wattage, the amperage at 120 volts is just 1/10 of that required for the same wattage at 12 volts. Higher amperage results in greater voltage drop. And a 120/240 multiwire branch circuit really helps with reducing voltage drop for long runs.

    Bookmark   November 25, 2008 at 9:01PM
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Hi! I don't know if they would like that, but do you remember these strings of C6 lights wired in series? Most of them were strings of 10 lights, meaning that the bulbs were 12 volt bulbs. Just do a search on Ebay for "vintage C6 lights" and you'll find all sorts of strings and bulbs. All you would have to do is rewire them in parallel.

    Bookmark   November 28, 2008 at 7:20PM
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