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# how many lights on one breaker??

#1
02-07-04, 07:43 AM
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Join Date: Jan 2003
Location: Michigan
Posts: 131
how many lights on one breaker??

How many lights can I put on one breaker?? I know there is an equation for this(something to do with breaker amperage vs. total wattage of lights) but I can't think of it.

And is it possible to use one breaker to control different sets of lights....what I mean is, I have three "areas" in my basement. I want each "area" to have its own light switch. Is threre a way to wire them all together so all I need is one breaker(Provided the total wattage is ok)? If so, could someone give a pretty detailed explanation? I'm assuming all you need to do is have the hot wire jumper to each switch.

Thanks for any info..if you have questions cuz I didn't explain myself well please yell.....

Ron

#2
02-07-04, 08:56 AM
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Join Date: Sep 2002
Location: welland ontario
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A 15 amp circuit can handle a maximum of 1800 watts. You only load it to 80% for calcultion purposes. You can have a maximum of 1440 watts on a 15 amp circuit.
That could be 144 10 watt bulbs or 14 100 watt bulbs. Use the maximum wattage rating of the fixture not the actual bulbs you are going to use for the calc.

A 20 amp circuit can handle 2400 watts loaded to 1920 watts.

#3
02-07-04, 09:43 AM
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The 80% figure for residential lighting is a recommended guideline, not a code rule. You should in general follow it, but it won't hurt much if you go over it a bit.

The instruction to use the fixture maximum is also a recommendation. If you're sure that you're never, ever going to use more than a 40-watt bulb in a 60-watt fixture, you can use the 40 figure.

All this usually isn't an issue anyway, because it's not very common to overload a lighting-only circuit.

Yes, you divide up a single circuit into lighting controlled by multiple switches. Although there are countless ways to do this, the most straightforward is to run the power from the breaker to switch1 to switch2 to switch3. At each switch, connect the power black wires to each other and to one of the screws on the switch using a pigtail. Once you've done this, then you can wire the switch to light cables, connecting the black wire from these light cables to the other screw on the switch. All white wires connect to each other in each box.

#4
02-07-04, 10:19 AM
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Join Date: Jan 2003
Location: Michigan
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John,

I failed to mention that these are dimmer switches....Does this make a difference?? Also, I'm putting ALL switches in one 4 gang box........the box will have 5 14/2 wires going into it. It is the deep style box. I believe this is ok??

Thank you all for your help,

ron

#5
02-07-04, 09:04 PM
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Four-gang switch boxes are generally a poor idea from a human-factors standpoint. Four dimmers in one box makes the idea even worse because of the thermal problems. That box will get pretty dang hot and the dimmers will likely not live to a ripe old age. But if you do the derating calculations provided by the dimmer manufacturer correctly, it is allowed.

Connect one wire from all four dimmers to the power cable black wire.

#6
02-08-04, 09:28 AM
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Location: welland ontario
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Check the rating on the dimmer switches. It might be 1000 watts but only 700 when ganged with others in the same box.

#7
02-09-04, 12:30 PM
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Join Date: Jan 2003
Location: Michigan
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Ok, I lied. There will be 2 dimmers and 2 regular switches. I'll just seperate the dimmers(one at each end of box).....Thank you all for your advice....I love this place!

ron

#8
02-10-04, 03:57 PM
imjerry
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Let try it this way

The Code says in residential occupancy 3 watts per square foot, for lighting but this is a minimum, I used 5 watts to be safe!! That includes all general purpose receptacles and general lighting!! However if you decide to go hog wild with OH lighting (High Hats) then a good rules is 6X150 Watts per circuit!! 12 Highhats in a ceiling I would feed with 1 3 wire 15 amp circuit 14-3
2 15 amp circuits!!! Watch out for dimmers and bulbs 6 X 15 = 900 watts, a 1000 watt dimmer!! Lutron Dimmers 1000 watt hum with 900 watt loads, and bulbs use Phillips not GE ( Ge's sound like bees) ( they cut costs by eoliminating 2 filament support wires!!!) The electrical code purposely did not specify the number of receptacles or light on a circuit to prevent poeple from not putting receptacles in needed places!!! So just use 3 or 5 watts per square foot plus any special circuits for appliances etc and you should be fine Jerry

#9
02-11-04, 07:58 AM
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Join Date: Jan 2003
Location: Michigan
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Jerry,

HUH?? No offense, but I got NO IDEA what your post means. Ya got to dumb it up a bit. The dimmers are 600w rated. Most watts that will be on one dimmer is 450w with my setup going with the highest rated bulbs for the cans.

ron

#10
02-11-04, 02:45 PM
imjerry
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Simply Put

There is no specific number of lighting devices on a circuit!!! size of the area example 10 X 20 ' 200 SQ feet X 3 W per Square ft = 600 watts Maximum loading for 15 Amp circuit is 1650 watts less 10% or 1500 watts approx!!! So a 10 X 20 area is more than adequately served by 1 15 amp lighting circuit!! Hope I made this clear !!!

Sorry if I didnt, but I tried!!! Jerry