number of recessed lights on one circuit


Old 12-13-04, 12:23 PM
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number of recessed lights on one circuit

Would someone please help with the number of lights I can put on a line. I plan to install recessed lights in my living room by pulling the power from a switched outlet currently in the room. I would like to install 10 fixtures. The room is 15' x 17' and plan to use 65W bulbs. I would prefer lower wattage but the big box stores don't carry the larger floods in less wattage and I want to use 6" recessed cans.

Thanks in advance for any help.
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Old 12-13-04, 02:01 PM
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What circuit do you want to pull power from? You are talking about 650 watts, which by itself is not much power. However, if you are talking about a circuit that is already near capacity then you will be in trouble.

My suggestion would be to run a new circuit for these lights.
Old 12-13-04, 06:47 PM
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Have you considered using compact flourescent floods?? You can buy these at any of the big boxes. You can get an 18watt that is coparible to a 75watt
incandescent. With 10 of them, you would only be pulling 1.5A on a 120VAC circuit compared to 10 65watters that would draw almost 5.5A.
Just a suggestion, but its all I use in my house. It also decreases your electrical bill considerably if used in your whole house.
Old 12-13-04, 07:01 PM
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I would not add 10 recessed fixtures to an existing circuit.

Don't forget, the load is based on maximum wattage. It's not what you put in the fixtures, it's what you can put in them. Using 65 watts means nothing if the fixture is rated for 75 or 100. You may not have the best light and need to use larger lamps which may overload the circuit. Not worth it IMO.
Old 12-14-04, 04:41 AM
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more questions.....

Thanks for the feedback. I don't think I can add another circuit to my panel. It's full and has a couple piggyback (i think that's what they call those two breakers in one) breakers already.

I hadn't thought of the flourescent bulbs, that would work although I understand the comment Speedy Petey made about the max rating. Ironically, I doubt most people pay any attention to those "max" wattage tags to begin with.

Is there any harm in adding the fixtures to the existing line. Am I just likely to trip a breaker if overloaded or am I creating a fire hazard? I think I could split the lights somehow and put 5 on one circuit and 5 on another. I'd have to cut some bigger holes (that won't make the wife happy) in the walls to install a second switch/power but it would still work.

Maybe this approach would be better. How many would be "ok" by tapping into the exisiting power at the outlet?
Old 12-21-04, 05:42 AM
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max number of lights I can add to a single circuit

Sorry to ask again but I'm not sure what I'm doing is safe. How many recessed lights would be ok to put on a line that is feeding outlets in a room.

Would I check how many outlets are on the circuit to begin with and use that to determine what my max would be?

How many outlets are allowed by code on a single 20A line to begin with?

Thanks in advance.
Old 12-21-04, 07:24 AM
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Safety of the circuit...

Originally Posted by mkhoch
Am I just likely to trip a breaker if overloaded or am I creating a fire hazard?
Breakers operate as the RESULT of an unsafe condition, not to PREVENT unsafe conditions. If a properly operating breaker trips it's because an unsafe condition already exists. The idea is for breakers to never operate. Breakers are like seat belts, they are there for your protection but don't put one on and drive into a wall.
As for Max Wattage, of course this should be considered when sizing the circuit but more importantly (or at least, just as importantly) it specifies how much heat the fixture can safely dissipate. Putting a 100w bulb in a 75w max fixture is a fire hazard not just because of the greater circuit load but because a 100w bulb produces more heat.
Old 12-21-04, 08:27 AM
Join Date: Dec 2004
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Capacity vs load...

Originally Posted by mkhoch
How many recessed lights would be ok to put on a line that is feeding outlets in a room.

Would I check how many outlets are on the circuit to begin with and use that to determine what my max would be?
Just an amateur's opinion, but it seems to me you have two basic issues. One, what's the capacity of the circuit, and two, what is its present load?

My understanding of how you calculate maximum wattageon a circuit is simply ((Volts)x(Amps))x80%. For a 20 amp circuit, that's 1920 watts.

Your problem is you have a potentially variable load situation. There may be nothing at all plugged into the outlets that are on the circuit you want to use, in which case your 10 can lights are well below the capacity limit. But since something COULD be plugged in to the outlets at any time, you're always exposed to an overload situation. While I can't say for sure that that's against code, I sure it is, and certainly should be.

Better safe than sorry with things like electricity! Best of luck with your project!

Old 12-21-04, 09:04 AM
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I would do a load calculation first to make sure the service is enough for all of the loads in the house. If your panel is already full you probably have a 100A service. If all appliances are gas (including heating and water heater) that should be enough. If however you have electric appliances you may run into problems.

If the service is large enough, you have 2 options. One would be to simply install another tandem (twin) breaker in the panel, if it allows. Second would be more elegant, and would allow for greater flexibility in the future, and it is to add a subpanel. You need to transfer 2 existing circuits to the subpanel to make room for the double pole breaker in the main. They you can easily add the existing circuit.

Going back to the lights, by itself the lights are not a very large load. However, unless the existing circuit is 20A and it only feeds that room (with nothing else "piggy backed" onto it it's not a good idea.

What exactly is that room, and what is on that circuit? You need to map all outlets/lights on that circuit, and plan a worst case scenario. If it is dedicated to the room, and you don't have any large wattage items on it it will probably be ok, with the most annoying side effect being the dimming of the lights when a large watter item (TV, vacuum, etc) is plugged into an outlet.
Old 12-21-04, 09:39 AM
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recessed lights

Thanks all for your comments. I think I'm confusing the questions though based on some of the comments.

What I'm trying to do, is install some recessed lights in my living room which has no lights in the ceiling at all. There is one switched outlet in the room which is where I was thinking of pulling power.

I plan to check to see what size breaker and what outlets that switch/outlet are on but I suspect it is not dedicated to that room alone. I don't know how many outlets are permitted on a single circuit or if lights can also go on a breaker that was wired for receptacles. I suspect it is ok as long as the load on the breaker is within its limits (someone mentioned a % of the total of 120V X 20A) whatever that is for receptacles.

What is the "expected" load on a receptacle circuit to begin with?

What I'm not sure about is the compliance to code of pulling power from that source, and how many would be acceptable. I had originally considered 10 lower wattage fixtures (40-50W) but am now thinking of 8 65W max fixtures (the ones that HD sells for $15 or so).

I don't need a sub panel for this I don't think, and while adding another circuit breaker and dedicated line would be the "best" solution, running wire through my finished basement is no easy task - although I have done it in the past.

My house is all electric (something I wish it wasn't....) and the main is 200A. Much of that is taken up by the heat pump/compressor/stove/water heater...

Your help please.....
Old 12-21-04, 10:04 AM
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I space them 4 feet a apart

I installed some in my house. I space them 4 feet a apart so each light can cover a 7 feet area. You would need to also see how you would set them up. I installed 8 of them. I'm use for dimer switch on a set of 2 in a set of 3 aother set of 3. So all will not be on at the same time. In you can lower the some of them for low lighting.
I use the old work light because it a lot ez when the celling is comepet. Cut your hole put it in.

This is aother way I installed them I ran all my wire way the drywall was down. put some tape on the floor wher the wire was located in where i won't the light to go at. I use a 2x4 to line up the spot. Put my drywall in place. Went back to the tape or mark on the floor with my 2x4 cut my hole out for my can/light there my wire. connect put can in place.
Old 12-21-04, 11:24 AM
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max cans

Originally Posted by mkhoch
Thanks all for your comments. I think I'm confusing the questions though based on some of the comments.

What I'm trying to do, is install some recessed lights in my living room which has no lights in the ceiling at all.
Mkhoch, it's not a question about whether you CAN install new lighting using your outlet as the power source. Absolutely, that can be done. It's a question of whether it's SAFE to do so.

You've said that the circuit you hope to use is a 20 amp circuit. That means that if you load the circuit at 100%, you can run 2400 watts at the same time. But you never want to max out a circuit, so you should design your maximum load using an 80% figure. If you do that, that comes to 1920 watts that can be run at the same time.

OK, you've got 10 cans you want to install using 65 watt bulbs. That's 650 watts. Great, that's way below 1920. So you install your cans and turn them on.

Now someone in your family comes along and plugs in a 1500 watt electric space heater in the plug that you grabbed the power from for the lights. Now you're running 2150 watts, well over the 80% figure, and uncomfortably close to the absolute max for the circuit.

That's your problem. You don't know who might come along and plug in something that will cause the circuit to overload. Also, YOU might plan to use 65 watt bulbs in the cans, but if the can is able to take a higher wattage bulb, someone later may user a bulb with that higher wattage. If the can can take a 150 watt bulb and someone installs 10 150 watt bulbs, that suddenly takes the light load alone to 1500 watts.

So the lights alone aren't really the issue. The issue is that because outlets are part of the equation, you can't reliably control the load that the circuit MIGHT have to sustain.

Old 12-21-04, 11:41 AM
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You need to know what's on that circuit, and if it is indeed a 20A circuit. Most LR circuits I've seen are not 20A. It's not the number of outlets that you have, but what is/will be plugged into those outlets. You need to calculate a worst case scenario. You need to do this using the maximum rated wattage for each light fixture, even though you may not put a light bulb that powerfull now.
Old 12-21-04, 12:17 PM
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I follow you...

I completely understand the comments you've made about what "might" be plugged in but what confuses me, is what is that "might" when running receptacles?

In other words, there is some number of plugs allowed on a 20A line. I don't know if that's how many are on this circuit, I'll have to check this weekend when I'm tinkering around. But let's say there are 10 outlets allowed on the 20A line. Given that I don't want to exceed roughly 1900W on those 10 outlets combined, that would leave me 190W per outlet service. What I'm saying is how do the codes take this into account? Who's to say someone won't plug a heater into every outlet (not likely but possible). Outlets aren't like light fixtures - the fixtures say "XX watts max" (which people ignore as well). No such thing for outlets.
Old 12-21-04, 12:29 PM
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Location: Chicago
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There is no restriction on the number of outlets allowed in the residential "world". You can have 1 outlet or you can have 100 outlets. Outlets don't consume any power, what you plug into that outlets does. Fixtures on the other hand are different, you need to look at them at maximum value. If the fixture says 100W maximum you have to use 100W, even though you may only put a 60W bulb in it.

What you need to do is shut off that breaker, and see what is not working (basically what is controlled by that breaker). After you've done this you need to substract all light fixtures from the 1900W (assuming 20A breaker), including the newly "to be added" fixtures. Then you need to think whether the remaining "power" will be enough to power anything else you may plug into any of those outlets (including the big and powerfull vacuum).
Old 12-21-04, 12:33 PM
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8 x 65 watts = 520 watts

5 hours use x 520 watts = 2600 watts used in one day

$0.20 per 1000 watts Cost

$0.20 x 2600 = $0.52 Cost per day

$0.52 x 30 days = $15.60 Cost per Month 5 hours per day

I never liked recessed lights.
The cheap ones. Like putting a 500 watt heater in the attic.
Old 12-21-04, 12:51 PM
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got it...

TRINITRO - Thanks. I'll figure it all this weekend.

GWIZ - interesting point but SWOMBO likes them so in they go.....

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