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#### lyngo

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I am designing a new home and would like to wire all of the lights on a 12 volt LED system. Where can I find if this will pass a electrical inspection. I will have custom plug ins for the lights and I want to run all the lights from a single 110v to 12v converter near the electrical box. most led lights you buy have a 110v to 12v converter built in and they are more expensive. This way I'm only running the wires to the lights and all lights are running off that one converter. Does anyone know if this will pass an inspection??

Thanks for looking!

#### joecaption

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Trying to figure out why this would be a good idea. Converter goes bad and you lose all the lights at once. It's going to limit you on styles of lighting fixtures drasticly.
Better to wire nomaly and use LED light bulbs. Oh by the way LED bulbs will cost about 5 times as much.

#### AllanJ

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At 12 volts, voltage drop can be a significant thing you have to plan around. You do need to add up the wattages of all of the lights to figure out the number and size of cables. Most likely the junction box from which separate cables branch off to different areas in the house needs to be very close to the transformer.

At 12 volts you need ten time the amperes compared with 120 volts for a given number of watts.

For a given piece of wire the voltage drop in volts (not percent) depends on amperes only, not volts.

Losing one volt out of 120 is miniscule whereas losing one volt out of 12 is significant. Also, if the number of watts is enough to lose half a volt out of 120 then the number of amperes representing the same number of watts at 12 volts will result in losing five volts out of 12 at the far end of the same cable.

#### a_lost_shadow

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Both AllanJ and joecaption bring up good points that you'll need to consider in your design. Also, think about how hard it will be for you or others to find replacement light bulbs in the future. If you decide to sell the home at some point, this may actually lower the value of the home. Finally, by custom plugins do you mean something you'll make or a custom product you've found?

Now if you still want to go ahead with this, I suggest you read articles 720 and 725 of the NEC. They deal with low voltage and power limited circuits. I've been doing some reading in these articles for a home automation idea I have. Unfortunately, there isn't nearly as much information on these outside the NEC as regular 120 ac.

Also I'd suggest having one transformer per light circuit. That way if one transformer dies, or one circuit gets tripped, you don't loose all the lights.

#### AllanJ

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You can actually string a circuit to 120 volt standards and energize it with 12 volts, subject to wire size needs for the length of the run. Someone wishing to convert it to 120 volts need only replace the light fixture and extend the end down in the basement directly to a panel breaker.

Low voltage wiring standards do not require outlet boxes but joints and splices still must be accessible. They make (usually orange colored) bottomless boxes to put on the studs to hold switches, etc. and their covers.

#### Julius793

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a_lost_shadow said:
Both AllanJ and joecaption bring up good points that you'll need to consider in your design. Also, think about how hard it will be for you or others to find replacement light bulbs in the future. If you decide to sell the home at some point, this may actually lower the value of the home. Finally, by custom plugins do you mean something you'll make or a custom product you've found?

Now if you still want to go ahead with this, I suggest you read articles 720 and 725 of the NEC. They deal with low voltage and power limited circuits. I've been doing some reading in these articles for a home automation idea I have. Unfortunately, there isn't nearly as much information on these outside the NEC as regular 120 ac.

Also I'd suggest having one transformer per light circuit. That way if one transformer dies, or one circuit gets tripped, you don't loose all the lights.
I believe he would need to look at article # 411 but I'll double check

#### dmxtothemax

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Why dont you use existing mains wiring,
Then use a 12v plugpack at each light fitting,
12v plugpacks can be sourced quite cheaply,
And so to can LED lamps.
This way you dont have to change any wiring !

#### theatretch85

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I could see this being a good idea only if the thought was to provide power via a battery bank and recharge circuit via solar power or other alternative energy. The idea of running a 12 volt low voltage system converted down from 120 doesn't make any sense. Like others have said the voltage drop would be a significant issue and finding bulbs for the special lighting may be difficult if and when manufacturing of them changes and if you ever want to change your style of lighting fixtures.

#### ddawg16

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I would not suggest doing this.....besides all the points noted above, there is a good chance that your 12v LED bulbs will not be around that long.

Lighting is sort of a hobby of mine....and while LED's have come a long way, I do not think they are the holly grail of lighting....I think the ideal lightbulb is still waiting to be invented....and when it is, it will most likely run on standard house wiring of 120Vac. Any voltage conversion will be done in the bulb.

If you wire everything up for 12V...you don't leave yourself very many options if you want to change it later.....in other words.....your locking yourself in a corner.

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