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12 volt lighting transformers ?

stormando | Posted in Energy, Heating & Insulation on January 23, 2010 12:53pm

I have no experience with 12 volt lighting. Besides charging alot of money for numerous transformers I don’t quite understand why its neccessary when I can buy a 3 light string of 20Watt Xenon Pucks that plug directly into 120V plug. Only other thing I can come up with is that a Pendant can have a thinner hanging cord if it’s 12 Volt rather than 120 Volt. What am I missing about 12 Volt? At any rate I am installing 8 each 20 Watt Xenon Triangle Under cabinet lights that will run off of 3 seperate 12 Volt Transformers on switched outlets. 3 each 35 Watt 12 Volt Pendant lights that each have their own transformer at ceiling box. And 3 each 120 Volt 3″ Halogen can lights AND 7 ea 120Volt 50 Watt 5″ Halogen can lights They operate just fine on a bunch of old extension cords and total Watts is way under 1,000 Watts. Is there any reason NOT to run these off of ONE circuit using 12-2NM on a 15 or 20 amp breaker? Is there anything about 12 Volt Transformers that I need to know and any reason to seperate this out on 2 seperate 15AMP 14 Gauge Circuits? Would adding any dimmer switches in the future change anything? Thanks anyone.

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  1. DanH | Jan 24, 2010 01:14am | #1

    You can't dim a transformer
    You can't dim a transformer circuit unless both the dimmer and transformer are rated for it.

  2. User avater
    kurt99 | Jan 24, 2010 12:48pm | #2

    I have not used the xenon puck lights but I have experience with both the 12V and 120V halogen puck lights. With these lights, the 12V give off a much brigher, whiter light. I was very disappointed with the 120V lights after using the 12V. The packaging didn't help tell me why I would want one or the other so I tried the 120V because it was a little cheaper. I ended up pulling it out and replacing it with the 12V.

    When thinking about it after the fact, I realized that it was a matter of physics that allows the 12V lights to operate hotter and thus whiter than the 120V without making a filament that is very fragile.

  3. Scott | Jan 24, 2010 07:43pm | #3

    >>>Only other thing I can come up with is that a Pendant can have a thinner hanging cord if it's 12 Volt rather than 120 Volt.

    This is a big deal for the marketing and design types. With 12V you can create intricate, light, sexy little connections on tiny wires without fear of electrocuting someone.

    Pendants aren't a big deal to install. You can get transformers that fit inside a standard octagon box, which is the standard box to support most surface-mount fixtures. Typically you cover the box with a dish that has a hole and bushing in the center through which the wire hangs.

    1. DanH | Jan 24, 2010 10:00pm | #4

      It should be noted that, with 12V, the wire actually has to be LARGER, but the insulation can be thinner (or none at all).

  4. pixburd | Jan 25, 2010 06:50am | #5

    stormando,

    You can add up low and high voltage lights on one circuit, with or without dimmers. 100 watts is 100 watts at any voltage. 15amp circuits with 14 ga wire are good for 100w total.

    Note that the output wire from the transformer is NOT 14 ga but rather 10 ga.

    I am currently combining the new G.E. 15w CFL dimmable floods in recessed cans for general lighting with 10w Xenon 12V undercabinet Linear lights. Used one 15 amp circuit for both. Used the same model dimmer for both.

    I like the Linears better since they don't create hot spots or bright spots like the Pucks do.

    1. User avater
      kurt99 | Jan 25, 2010 09:44am | #6

      A 15 amp circuit is good for a lot more than 100W. About 1500W which should give you a little cushion. 15 amps at 120V is actually 1800W.

      1. pixburd | Jan 25, 2010 02:33pm | #7

        Thanks, my bad. I left out a zero.

        I meant to answer Storms question about whether a 15 amp ckt was adequate for up to 1000watts of ltg.

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