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# Low voltage outdoor lighting

#1
11-04-10, 07:48 PM
Member
Join Date: Sep 2010
Location: MN
Posts: 55
Low voltage outdoor lighting

Hi all-

I have a question about low voltage lighting. On Saturday I plan on installing some low voltage deck and step lights. I purchased a 200w transformer, 17 lights (plan on using 4w bulbs), and 100ft of 16/2 wire. I know that the 16 gauge wire should be sufficient for this but am wondering if down the line if I want to splice (or add on) to this 100 feet of wire is it okay to do so? I read the back of the wire and it states to only use a maximum of 100 feet of 16/2, 100 feet of 14/2, or 125 feet of 12/2. That can't be right, can it? I know that 16/2 is pushing it.

So I guess the question comes down to this. Can I splice and have 2-100 feet total run of 16/2 wire or would it be better to have 2-100 feet of 14/2. If I do add on light they would probably be around 10 lights w/ 7 watt bulbs (total wattage of 138).

Thanks,
Sean

#2
11-04-10, 08:40 PM
Member
Join Date: Oct 2005
Location: Milwaukee WI
Posts: 1,338
Originally Posted by SeanJ
Hi all-

... 200w transformer,
...17 lights (plan on using 4w bulbs)
...100ft of 16/2 wire.
...if I want to splice (or add on) to this 100 feet of wire is it okay to do so?
...Can I splice and have 2-100 feet total run of 16/2 wire or would it be better to have 2-100 feet of 14/2.
Largest reasonable gauge is better. On a 12V system via 16 AWG you may find a somewhat lower voltage at the end of the cable. That means your bulbs out there will be drawing more current.

Some transformers have multiple taps so you can set the voltage a bit lower or higher to compensate for distance.

At any rate, with longer cables and higher total wattage you want larger AWG. So 14 AWG gives you more flexibility and current-carrying capacity than 16 AWG. But whether that's significant depends on the transformer, the quality of the splicing and light connections, and the current draw of the bulbs.

I use 12 AWG for all the long runs, and then splice in 14 or 16 AWG in the garden beds where the underground 12 AWG pops out.

Also pay attention to the quality of the connections. I am not a big fan of the cheapos that just pierce the insulation on zip cord. They corrode easily. That increases current draw and ultimately the connection is lost, which increases the voltage to the other bulbs. Then the bulbs can die prematurely.

12V systems can be high maintenance. Just so you know.

#3
11-04-10, 10:28 PM
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,046
You might want to consider placing a 120v AC receptacle at the 100 foot mid point and either use two transformers or a transformer with connections for two runs. That way none of the LV runs arelmore then 100 feet.

#4
11-05-10, 03:47 PM
Member
Join Date: Sep 2010
Location: MN
Posts: 55
thanks guys for the responses. I think what the new plan is is to use 12/2 wire. I think it will be the best solution and probably less problems.

My other concern is is it okay to have about 30 feet of unused wire in the middle? I will be starting with fixtures on the deck (13 fixtures x 4 watts) then down to the stairs (4 fixtures x 4 watts) then there will be about 30 feet to wrap around the house to the driveway where those lights will start. Is this going to be an issue?

Thanks again,
Sean

P.S. I noticed I posted this in the wrong forum so if a mod wants to move it please do

#5
11-05-10, 06:23 PM
Member
Join Date: Oct 2005
Location: Milwaukee WI
Posts: 1,338
Originally Posted by SeanJ
...new plan is is to use 12/2 wire.
...is it okay to have about 30 feet of unused wire in the middle?
I don't see a problem with that. For a long time I ran a 12 AWG line that had three lights about 10' from the transformer, then a 50-foot run to four more lights. I never had issues with bulbs blowing or anything too bright or too dim. That was a little cheapo transformer, too.

#6
11-05-10, 06:55 PM
Member
Join Date: Sep 2010
Location: MN
Posts: 55
Originally Posted by ArgMeMatey
I don't see a problem with that.
Sounds good. Thanks ArgMeMatey. I really didn't want to buy they 12/2 because it's twice the price as 16/2 but I suppose if you're going to do it, you might as well do it right.

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