12 volt lights on line voltage (110V)

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Old 09-07-05, 11:12 AM
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12 volt lights on line voltage (110V)

I just installed a set of 12volt lights using the supplied transformer. They work just fine. Here's my question, I know folks that have wired their 12 volt light strip directly into the house voltage bypassing the transformer. They tend to glow very dimly. I understand that the reason they stay dim has to do with the laws of electricity and I'm curious to know what that law is.
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Old 09-07-05, 11:25 AM
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12-volt lights connected to 120 volts would not glow dimly. They would burn very brightly for their very brief lives. OF course, they would then be really dim.
 
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Old 09-07-05, 03:21 PM
Sparky375
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what you may be seeing is they use 14/2 wire to the point of attachment and they hide the transformer in a cab.
 
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Old 09-07-05, 08:08 PM
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Anyone remember series wired Christmas lights?

joeperi, the problem is that your light strip is wired in parallel. One contact of each bulb goes to one side of the power source (transformer ) and the other contact goes to the other side of the power source. For 12V bulbs you need a 12V transformer.

If you could find a light strip where one side of the power source went to one contact on the first bulb, and the other contact was wired to one contact of the next bulb and so on until, at the last bulb in the string, the final contact was wired back to the other side of the power source, you would have a series circuit that could be plugged directly into a 120 V recept. The number of bulbs at 12v would be 10 or the number of bulbs at 3 V would be 40. The downside is that one bad bulb breaks the circuit and the whole string goes out. Modern miniature Christmas lights have a shunt at each bulb, so that one can go out while the rest still burn.

To get dim with the series ciruit, you just add more bulbs. Twenty 12V bulbs in series would add up to 240 V. Since you only have 120 V available, they would glow at half brightness - or less.
 
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Old 09-09-05, 05:22 AM
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Dear all, thanks for all the comments and suggestions. It never occurred to me that the strip could be wired in series. We have searched in every nook and craney and can find no transformer. So either it's buried in a wall or it is line voltage connected. Next step is to throw a voltage meter on the strip.
Again, thank you all for your feedback.
 
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Old 09-09-05, 06:32 AM
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Are you talking about the new set of lights you installed, or some other set of lights? If the latter, what makes you think it's a low-voltage lighting?
 
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Old 09-09-05, 06:45 AM
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These two statements seem to contradict each other...

"We have searched in every nook and craney and can find no transformer."

"I just installed a set of 12volt lights using the supplied transformer."

Care to clarify...
 
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Old 09-09-05, 09:00 AM
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I thought that he was referring to a friend/neighbor who has the direct feed 120 lights, while the one's he installed use the 12 V xmfr.
Clarification would be good.
 
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Old 09-09-05, 09:44 AM
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Dear all, sorry 'bout the confusion. Goldstar's understanding is correct. The problem is exclusively my neighbors. He asked me to look at it because I had just installed one successfully. In reply to John Nelson: because the neighbor said that is what he had requested so he assumes that is what the electrician installed (electrician no longer reachable). We have looked EVERYWHERE for a transformer but cannot find one. Furthermore, the bulbs are the type you typically see in low voltage situations: pins on both ends and the bulb holders are set into a strip of wire laid into a channel. So, yes we are making the assumption that it is a 12v system.
 
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