Out door - Low voltage lighting installation


Old 02-24-11, 12:12 PM
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Join Date: Apr 2008
Location: Florida
Posts: 37
Out door - Low voltage lighting installation

Need some advice on an out door lighting project I need to do at sons house in CA... Thanks in advance for reading through this...

I would like to run low voltage lighting for an approximately 70 foot run with lights at (let's say) every 6 feet. I believe I can tap into (need to check out what else is on line - not sure if it is on a GFI breaker in box) an unused outside 15 amp (14-2 wire) connection. This connection is aproximately 6 foot away from a new retaining wall above which I want to run the lighting. I have allready installed a gray 40 PVC pipe in the wall and have access to it at the base of the wall and at he top for drawing wire through. I will want to run 3 of the lights to the right of the pipe and the re maining 9 to the left. What I need help with is :
ideas on running the wire from the outside connection (type of wire, gauge, how deep to bury the pvc which it will be in), the best type of external outlet box to use, the type/size/voltage rating of the transformer and wiring, the type of outlet box to use for spliting the run of lights and best way to split it. And of course what is the best way to ground the installation... Anything else you care to share would also be greatly appreciated.

Thanks again...
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Old 02-24-11, 01:31 PM
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Join Date: Feb 2005
Location: Near Lansing, Michigan
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Originally Posted by williammartin View Post
an unused outside 15 amp (14-2 wire) connection.
You can use this circuit as long as it doesn't feed a dedicated appliance, the kitchen, bath or laundry. Splices must be made in accessible junction boxes with enough slack. That usually means if you're cutting into an existing cable that you will actually need to install two junctions boxes about 16" apart. The outdoor receptacle will need to be GFCI protected.

the best type of external outlet box to use
If the box is inside building but opens to the outside, any standard box will do provided that you install a weatherproof in-use cover and seal/caulk it appropriately. A siding block may be necessary to get a good seal if you have tapered or vinyl siding. If the box is entirely outside the building you need to use a die-cast aluminum or plastic outdoor "bell" box with in-use cover. The wiring method must also be waterproof. The most common method would be UF-B cable.

the type/size/voltage rating of the transformer
Depends on the wattage of the lights you want. Add up the wattage of the fixtures and add 10-20%, then get a landscape transformer rated for at least that size. The LV cable should be #14 or #12 landscape light cable -- they sell this and all the accessories for it at the home center stores.

spliting the run of lights and best way to split it.
I would run two separate pieces of low voltage cable and twist them together on the transformer screw terminals.
Old 02-24-11, 09:21 PM
Join Date: Apr 2007
Location: Near Buffalo, NY
Posts: 4,239
Check the transformer. Many are not rated to be used indoors.

Also, if you're using nine 20-watt lamps over that 70-foot run you may need to use 12awg landscape wire instead of 14 or the lamps at the end of the run will be noticeably dimmer than those closest to the transformer.

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