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8roty 07-16-2009 10:57 PM

wiring basement lighting
1 Attachment(s)
I'm finishing the basement...... I already modified some wiring (separated ceiling lights into 2 separate circuits with their own switches). The utility area is powered back up and working with the newly located switch. The other lights in the finished area have been removed and have been replaced with canned lights. I have return air through floor joists so I can't take the shortest route between the canned lights, rather than run a bunch of wire to a canned light and back to continue to the next, can I branch off 2 or more lights off of 1 light? See attached basic diagram.

Second, I made a half-wall at the bottom of the stairs into the basement. The 3-way switch had a wire going up to a light at the bottom of the stairs, this light is in a finished ceiling area so I cannot remove to replace with a longer length of wire. With the half wall I had to run-out the wire further and now the wire cannot reach the exisiting 3-way switch. It can however reach the wiring box for a new smoke detector so I ran the wire there and then extended it to reach the switch. Is this allowed, I'd rather do this than have a junction box.

Thanks in advance for anyone's advice and help.

kbsparky 07-17-2009 05:42 AM

Too many wires in that first can light.

Yes, you can hide a splice in the back of the smoke alarm box, provided you have sufficient cubic inch volume for all the conductors.

300zx 07-17-2009 07:07 AM

Run 3 wire between the two three ways and then one out to light 12-2 then light to light.And power to switch box not to can to many wires in there.

8roty 07-17-2009 10:14 PM

Do I understand correctly, I need 12-2 wire to go to the first can light from 3-way switch #2? Is 14-2 wire sufficient to run from light to light? And must I run wire from light to light in series or can I branch off from one can light to power 2 different runs of lights connected end to end?

Thanks again!

KeithM62948 07-17-2009 11:55 PM

You use #12 wire throughout the circuit if it is protected by a 20 amp breaker, use #14 throughout if it is protected by a 15 amp breaker.

You should be able to branch from one light to 2 seperate runs if there is room in the attached junction box.

javier 07-18-2009 09:09 AM

your putting power at the light and the three ways are dead end are you ok on that its a little different so im just asking i can tell you how and you look in the box on the can an see how many wires or how many cubic inches it says

8roty 07-23-2009 06:49 PM

I can re-run the wire to have switch#1 to switch #2 to the can lights. However, is the diagram I posted OK??,..... it sounds like from the responses that there are too many wires in that first can light. The interior of the can light reads: MAX OF 8 NO. 12 AWG (4 IN 4 OUT) THROUGH BRANCH CIRCUIT CONNECTORS.
Does this mean that running 2 14-3 and 2 14-2 wires into that box is OK?

javier 07-23-2009 07:04 PM

the truth is no if it holds 8 #12 wire that means that box is 18 cubic inches when calculating 14 wire you multiply by two so you have 2 #14-3 so that is twelve cu in then you have 2 #14-2 witch is 8cu in and then the ground is 2 so you have 22cu in

8roty 07-23-2009 08:01 PM

Thanks for the explanation, at first i was really confused with the numbers and calculation but I think I understand it now. So 3 #14-2 wires in a light (1 incoming, 2 outgoing if I make a branch to 2 separate runs of lights) would total 14 cu in?

8roty 07-23-2009 08:26 PM

1 Attachment(s)
Here is an updated diagram, everything check out OK?

jovingo 07-23-2009 09:38 PM

Much better. The boxes will be less crowded and you will only need one 14-3 cable.

javier 07-24-2009 05:52 AM

looks good and easy

8roty 07-25-2009 10:07 AM

When I use an existing box with enough sq in to make a separate connection to extend another run, do the grounds from both runs need to be connected together in the box? I connected them separately but I think I saw somewhere that they should be connected together.

jovingo 07-25-2009 10:40 AM

Tie all grounds together and make sure the grounding conductor is also bonded to the box if it is a metal box.

DandHJohn 07-25-2009 06:00 PM

For the breaker in a basement application such as this one, should a 15A GFIC be used instead of a normal 15A breaker?

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