Low Voltage Lighting and Building Code


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Old 05-28-06, 07:49 AM
J
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Low Voltage Lighting and Building Code

I was reading a copy of The Family Handyman (magazine, May 2006) about low voltage lighting for your deck. A statement in
the artcile indicated that any lights installed on the house
should be 110V not low voltage as on the actual deck. The article didn't explain why.

Since I had a plan for future low voltage lighting in which some
of the lights would be mounted on an outside house wall, and
some of the low voltage wiring would be routed through the soffit area. I now wonder if there is a building code, or safety issue regarding low voltage wiring in or on an occupied structure. Can anyone enlighten me in this area. (I'm in Florida, but since the magazine is national I'm sure if the remark dealt with a code issue it would be part of the national building code).

Thanks,
Jim
 
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Old 05-28-06, 08:39 AM
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I did not read that article so I may not be answering your question, but I will give you my two pennies on the topic of low voltage lighting.

People seem to believe that low voltage means safer. This is not 100 percent true. In order to get the same wattage from a device, like a light, you need a higher amperage at a lower voltage. Since amperage is the element in an electrical system that causes heat, the higher the amperage the more heat is generated in the wiring system.

For the higher amperage to be safe, a larger size wire is needed.
Three 60 watt lamps at 120v would draw 1 and 1/2 amps
At 12 volts 15 amps is needed to get the same wattage.

If the proper size wires are used and the connections are all made correctly this is not likely to be a problem. The problem is that with the mind set that low voltage is safer people are more likley to take short cuts etc with the low voltage than they would with the higher voltage.

The wattage will also be the factor which determines how much actual light can be produced.

Typicly on a deck the low voltage lighting is just for ambiance. A lower wattage system works fine for this. The lights on the house are for illumination. A higher wattage is more desireable therefore a higher voltage is more practicle.
 
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Old 05-28-06, 10:09 AM
J
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Low Voltage Lighting

Thanks for the quick reply. The article referenced starts on
page 71 and the "NOTE" about using 110V is in the last two
sentences of the article on page 77.

The amperage you stated is startling, but the physics is easy
to calculate to bear it out. Definitly good advice and info to
always keep in mind.

In my application I have a 26 x 44 pool deck bounded on 2 sides
by the house and on the other long side by a block (poured solid) retaining wall. Full illumination is taken care of by a couple of soffit mounted flood lights. I was thinking about lighting for ambiance. Specifically I thought about the small, surface mounted shaded round low voltage lights (7 to 10W?) mounted under the soffit to provide some small pools of light around two house sides of the perimeter of the pool deck.

Sounds like this might not be a safe way to go. I haven't seen 110V, low watt, damp location, fixtures in the same size range.
Do you have an idea where I might find them or a better solution entirely?

Thanks,
Jim Teller
 
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Old 05-29-06, 06:22 AM
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I would go with the low voltage. just be sure to size your wires correctly. and follow the mfg instructions for making connections. If done properly low voltage lighting is safe.
 
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Old 05-30-06, 07:13 AM
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Thanks

Thanks again. I'll check out the low voltage fixtures
I'm thinking of to see if I get the "mood" lighting I am
expecting. If that looks good then no reason not to
get heavy guage wire. The run alone, over 60 feet
would seem to demand it, then your advice would
emphasize it, and the additional cost is well worth the
safety. Appreciate yourf feedback and direction.

Jim
 
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Old 05-30-06, 12:28 PM
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The LV cable cannot be run through the soffit area. You must use one of the Chapter 3 wiring methods like non-metallic cable.

I believe you may also have an issue with the LV lights being too close to the pool. But it is hard to tell your exact setup by your description. Check with your local building department.
 
 

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