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# How many can lights can you put on one circut?

#1
02-05-05, 07:00 PM
Sawdustguy
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How many can lights can you put on one circut?

In my girlfriends house, she has one light fixture in her kitchen. I will be doing the electrical work on this too. ::Sigh:: Only one way to learn.

How many can lights can I put on one circut? I believe the only thing on this circut is the light, a few wall outlets and the hall light. "From what I know so far"

I would like to put 9 can lights on a 3 way dimmer. If she has a 15 amp breaker for that circut, should I switch it to a 20 amp?

Thanks

#2
02-05-05, 07:19 PM
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A 15-amp circuit can supply up to 1800 watts. A 20-amp circuit can supply up to 2400 watts.

So if you had a lighting circuit, you could put up to 1800 or 2400 watts of bulbs on it. When the lighting shares a circuit with receptacles (common, but no the greatest idea in the world), you have to factor in what is or might be plugged into the receptacles. If the receptacle might get the vacuum cleaner, you might only have enough left for 300 watts of lighting. If the receptacle might be used for a hair dryer, you might not have anything left at all.

So you can see that the answer isn't simple. It takes careful planning. Remember that when the electrician wired this circuit to begin with, he already put all the loads on it he thought it could handle. So adding anything must be done carefully.

Nine can lights with a 75-watt bulb each is 675 watts. Most dimmers are only rated for 600 watts, but some are rated for 1000 watts. You will need the 1000-watt dimmer, and even then, it will get really warm.

Unless you have really terrific fire insurance, never, ever, ever change a 15-amp breaker to a 20-amp breaker.

#3
02-05-05, 07:26 PM
Sawdustguy
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So the answer would be to run a new breaker with new wires through the existing conduet? 12 Gauge wire? Do you recommend Strand or Solid? Any other recommendations?

If I shut off the main power breaker in the panel, Does that kill ALL power to the house on every circut and through the panel?

The house was built in the 70's

#4
02-05-05, 07:32 PM
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If you have the panel space available, a new circuit is always the preferred solution to new loads.

12-gauge wire is good.

There are two different considerations when adding new wire to existing conduit. Too many wires in one conduit can cause both (1) derating issues, and (2) conduit fill issues. To figure if the conduit can handle it, you'd need to tell me how many wires are currently in the conduit, what size and color they are, how big the conduit it is, and what type it is.

#5
02-05-05, 07:49 PM
Sawdustguy
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From what I noticed. "I would have to look to give you an exact answer" but I think 1/2"

I think there is only 1 black, because the other black is getting power from the opposite side "Hall Switch" which is back to back with the kitchen box. Two seperate boxes. One black wire is tapped off of the hall box to the kitchen box to give the kitchen main light power. The other two wires which are attached to the switch and go to the actual light are yellow. So the pipe going up from the box has 3 or 4 wires going up to the light. "I would have to look"

So knowing this, I assume that I'm good with the wires coming from the panel and could add 2 more.

To give you exact answers, I'll have to get back to you on that, probably tomm.

#6
02-06-05, 07:45 PM
Tim_Paget
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Hey John...when you say never go from a 15a to a 20a, is that assuming the original circuit is run with 14g? Just wondering, thanks.

#7
02-06-05, 08:47 PM
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Location: United States
Posts: 18,497
99.999% of all residential circuits in the U.S. which are protected by a 15-amp breaker are wired with 14-gauge wire. The exceptions are so rare that it's not even worth mentioning.

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