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nelsonC 05-21-2010 12:18 PM

1-pole switch, multple fluorescents: wiring question
I have a question about how to wire three fluorescent fixtures, switchable by one switch.

I'm looking at this diagram (try to imagine a third fixture in here):

Instead of going from fixture #1 to #2 to #3 in succession, is it possible to divide the wires in a junction box after #1 and go to #2 and #3 individually?

Also, what happens at the end of this circuit? The diagram says "wire out to two more receptacles," but in my case, the last light is the final fixture. Is it unnecessary to run that black wire between fixtures and therefore unnecessary to use 12-3?

Thank you!

Troglodyte 05-21-2010 01:19 PM

The three wire won't be necessary if:

a) it is the end of the circuit
b) you want everything on the circuit to be controlled by the one switch

If you really want everything off the one switch then you don't need a three wire line. You can put in a junction box right after light #1 and run to #2 and #3 separately, or run them with 2-wire sequentially.

However, if you ever want to run another fixture/outlet off that line in the future, it will be controlled by the same switch unless you use the three wire method shown in your diagram.

nelsonC 05-21-2010 01:28 PM

Thanks for the response.

One switch for the three light fixtures is all I need. So, if I use 2-wire only, is this correct:

- Black wire from source to white wire from switch
- White wire from source to white wire on fixture #1, pigtailed and sent to white wires of the next two fixtures (ending at fixture #3)
- Black wire from switch to black wire on fixture #1, pigtailed and sent to black wires of the next two fixtures (ending at fixture #3)

Thank you!

joed 05-21-2010 01:44 PM

1 Attachment(s)
There are so many different ways to do this. It depends on if you bring power to one of the lights first or the switch first. In your diagram you could simply eliminated the black wire to the second light and change the red one to black. The ongoing cable to recepatcles is just not used.

Attachment 20740

nelsonC 05-21-2010 02:02 PM

Very helpful, thank you!

In this diagram, the power is coming to the switch first, right?

Also, if I wanted to put another light somewhere far off that diagram, is it okay to splice the black and white wires that run between those two fixtures and send my new wires to the (not pictured) fixture, to make the routing more efficient?

Troglodyte 05-21-2010 04:09 PM

If you go with the two wire configuration and splice anything after the first switch or fixture and run it somewhere else the switch will control the power to that new outlet/fixture as well.

joed 05-21-2010 04:48 PM

2 Attachment(s)
In that diagram the power is going to the light on the left first. You can add more from any of the light fixture by simply connecting to the black and white that are connected to the fixture. I marked red X where you can connect for additional fixtures. I also cleaned up the white wires a bit. It was confusing looking.
You can't splice in the middle of the cable unless you install a junction box. All connections must be in accessible junction boxes.

Attachment 20746

theatretch85 05-21-2010 07:41 PM

One thing that should also be noted, when using a switch loop (as in the diagrams above) the white wire must be marked to re-identify it as a hot conductor. This is usually best done with a black sharpie, in some cases you can get by with just plain old electrical tape.

nelsonC 05-24-2010 08:04 AM

Thanks for the suggestion. I marked the white wire with electrical tape.

The project went very well this weekend, thanks again for all the assistance.

Two more questions came up, I'm hoping to get a couple more answers:

1. The first light fixture (and the only original one in the project) is in the basement stairwell. It's round and attaches to the face of the beam that goes across the stairwell at the bottom of the stairs (watch your head). The back of the Frisbee-like fixture is just insulation and the wires tuck into the insulation and press against the wood beam. This is the first fixture in the loop, so there are now a few more wires to tuck in there. My question is, is this okay? Or, should I make all my connections in a junction box up in the joist bay and then just run two of the wires to the fixture?

2. There is one fluorescent fixture at the end of the run. It's above the washing machine. Is there anything wrong (or dangerous) about adding a separate switch for this fixture? I figure I can just put another single pole switch in line there. I realize that the light won't work unless the main switch at the top of the stairs is on, but that's okay because it's always dark in our basement and you'll have to turn on the main switch before going down there anyway. We'll always want the stairwell and main lights to come on, but won't always need the washing machine light to be on.

Thank you!

brric 05-24-2010 08:20 AM

All of the wires at the beam should be in a j-box. Easiest thing to do at the other fixture would be to install a pull-chain switch on the fixture.

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