Multiple switches and lights on one circuit

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  #1  
Old 05-26-05, 02:57 PM
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Multiple switches and lights on one circuit

I want to have 3 switches in a box that each control two flourescent lights. I'd like to do this on one circuit.

Can this be done (properly), and how do I wire it? I started sketching out a diagram, but I'm just confusing myself.
 
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  #2  
Old 05-26-05, 03:16 PM
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PR = Power Romex
RL1 = Romex supplying power to first pair of lights
RL2, RL3 = same as above to 2nd/3rd respectively
L1A = First light in the first pair of lights
L1B = Second light in the first pair of lights
Then there's L2A, L2B, L3A, L3B...You get the picture
SW1, SW2, SW3 = Switches 1, 2, & 3

Wire runs:
1. PR comes from the breaker box, into the three gang box.
2. RL1 is ran to L1A. A romex is also run from L1A to L1B.
3. RL2 is ran to L2A. A romex is also run from L2A to L2B.
4. RL3 is ran to L3A. A romex is also run from L3A to L3B.


At the switch box, wirenut ALL whites together.

Make 3 bare pigtails (4 if box is metal) and wirenut them together with all the bare wires. Connect one pigtail to the box if metal, then one pigtail to each switches green screw.

Make 3 black pigtails. Wirenut the three of them to the black wire from PR. Connect each of these pigtails to one of the screws of each switch. Connect the black of R1A to the other screw of SW1. Repeat for R2A and R3A to SW2 and SW3 respectively.

Now you are done @ the switch boxes...


At L1A, you will need a black, white, and bare pigtail (two if box is metal). Wirenut the black pigtail with the two blacks, white with whites, bare with bare. Connect these pigtails to the fixtures black, white, and ground wires (and box if metal).

Repeat for L2A and L3A.

At L1B, L2B, and L3B, simply connect your colors...Be sure to pigtail the ground wire to box if it is metal.

All Romex is 12-2wg if on a 20A breaker, 14-2wg if on a 15A breaker. If you have to something other than Romex, just substitute as needed.
 
  #3  
Old 05-26-05, 04:06 PM
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lol Holy crap, I'm giong to have to draw that out to understand it. Thanks!

What do you mean exaclty by "pigtail"?
 
  #4  
Old 05-26-05, 04:09 PM
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Originally Posted by chirkware
Connect the black of R1A to the other screw of SW1.
Wait, what's R1A?
 
  #5  
Old 05-26-05, 05:27 PM
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You are only allowed to put one wire under a screw. When you have more than one wire that needs to connect to the same screw you connect them all together with a six inch piece of wire with a wire nut. Connect that six inch pigtail wire to the screw.
 
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Old 05-27-05, 07:54 AM
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Cool, I got it figured out now, after I sketched it all out.

One question about boxes for the flourescent lights - what is required? Do I need to cut thru the sheetrock to expose the entire box, or can I just drill a hole big enough for the wires to go thru? I'd like to limit the size of the holes I drill, in case I decided to relocate or remove a light.

Can I wire-nut the wires inside the fixture, or is that against code?

Can I just install a box that does't go thru the sheetrock, and just feed the wires from the fixture(s) and the switches into the box, and wire-nut inside the box?
 
  #7  
Old 05-27-05, 08:22 AM
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Because almost all fluorescent fixtures provide a wiring compartment as part of the fixture, and because the fixture does not mount to the box, electrical boxes in the ceiling are optional. You can just poke the cable through the drywall if you want.

You can (and must) use wire nuts inside the fixture.

If you want, you can use a box that is recessed behind the drywall, but if you do so, you cannot make any splices in it--the splices must be in the fixture. That's pretty much the same as leaving the box out completely since the box is serving no purpose.
 
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Old 05-27-05, 08:52 AM
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Awesome. I'm going to wire up about 10 8' flourescents between two breakers, so I'll pick up a couple 15A breakers and some 14-2 tonight. The only reason I'm splitting it into two circuits is b/c I think the wiring will be easier. (There will be three switches in one box, two switches in the other.)

Edit: On the other hand, I suppose I *could* wire all 5 switches from the same breaker. Would 15A and 14-2 be sufficient here?
 
  #9  
Old 05-27-05, 09:16 AM
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Originally Posted by Weez
Wait, what's R1A?

Sorry about that...I goofed on my owned terminology.

That would be RL1.


Since you are talking 10 total fixtures, and questioning use of one 15A circuit, and since you have to buy the parts...just go with 12-2 and 20A to be safe...


I'm headed out of town, so I won't be able to check back for a few days. John, joed, and others here are WAY more knowledgeable than me anyway, so you won't miss me. lol
 
  #10  
Old 05-27-05, 09:41 AM
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A 15 amp circuit can easily handle ten fluorescent lights.

There might be reasons for two circuits, however. If you would want to be able to work on one circuit while the other is shut off, or if you need lighting in the event that the circuit for some reason trips the breaker. Neither of those are, in my opinion, strong reasons for a second circuit.
 
  #11  
Old 05-27-05, 10:24 AM
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Originally Posted by racraft
A 15 amp circuit can easily handle ten fluorescent lights.

There might be reasons for two circuits, however. If you would want to be able to work on one circuit while the other is shut off, or if you need lighting in the event that the circuit for some reason trips the breaker. Neither of those are, in my opinion, strong reasons for a second circuit.
Cool. I have 12-2 on hand, but I'll use most of it for the receptacles. I'll go buy some 14-2 and one 15A breaker for my lights.

I'll just wire up my first switch box as described above, then pull another Romex from switch box 1 to switch box 2 (I'll tie in the white/black/bare to the pigtails in box 1 that are already wire-nutted) and wire up box 2 and the associated lights the same way.

Thanks for the help, everybody!
 
  #12  
Old 05-27-05, 10:37 AM
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It's just a function of wattage. A 15-amp circuit can handle up to 1800 watts, so add up the wattage of your bulbs. Some people like to limit themselves to 80% of the 1800 (i.e., 1440), but you don't have to in a residential unless it will be typical that all these lights will be left on all day. And some people like to leave room to add more later.

It's easier in the future to combine two circuits into one than to separate one circuit into two.
 
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