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Old 07-10-2011, 02:50 PM   #1
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How many wires can be tapped into a light fixture?


Greetings,

I want to install one recessed light at the bottom of my stairwell. I can easily tap into another light fixture in the ceiling of my basement. My question is, is it safe to run the wire from my new light and tap into an existing light. The existing light already has two wires coming from it which I assume one is from the next nearest light and then another feeding the next light. Basement ceiling has about 8 ceiling lights.

So basically if I tap into the light I want to, it will then have 3, 14 ga wires into it. Will be be an overload? The light fixture box has 4 slots allowing wires to enter it and only two are being used.

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Old 07-10-2011, 03:10 PM   #2
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How many wires can be tapped into a light fixture?


When you say "two wires" do you mean exactly "two wires" or do you mean 2 cables? If the latter, we need to know how many wires are in those cables.


Last edited by sirsparksalot; 07-10-2011 at 03:10 PM. Reason: spelling
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Old 07-10-2011, 03:39 PM   #3
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How many wires can be tapped into a light fixture?


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Originally Posted by sirsparksalot View Post
When you say "two wires" do you mean exactly "two wires" or do you mean 2 cables? If the latter, we need to know how many wires are in those cables.
I'm sorry, 2 cables. Appear to be 14/2....one black, one white and a bare. To wire in the new light I will be also using 14/2 that has one black, one white and a bare (ground).
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Old 07-10-2011, 09:45 PM   #4
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How many wires can be tapped into a light fixture?


Overload here has to do with size of the box and number of wires, not the kind of fixture or the number of amperes or watts. You need 2 cubic inches for each 14 gauge wire end entering the box, however count 2 ci just once for all the ground wires. Add 2 more ci for all of the wire clamps that protrude into the box. Add 4 ci for each switch or receptacle unit inside the box. Nothing needs to be counted for short lengths of wire (pigtails) completely in the box and for wire nuts.

Most recessed "can" ceiling lights have a small box for connections off to the side of the "can". The small box usually cannot accept more than two cables each with a hot wire and a neutral wire (and a ground wire).

Just because the box has 4 slots for cables to enter does not mean you can use all of them. The 4 slots are for such situations as cables entering from the top versus entering from the bottom.
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Last edited by AllanJ; 07-10-2011 at 09:49 PM.
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Old 07-11-2011, 01:41 AM   #5
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How many wires can be tapped into a light fixture?


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Overload here has to do with size of the box and number of wires, not the kind of fixture or the number of amperes or watts. You need 2 cubic inches for each 14 gauge wire end entering the box, however count 2 ci just once for all the ground wires. Add 2 more ci for all of the wire clamps that protrude into the box. Add 4 ci for each switch or receptacle unit inside the box. Nothing needs to be counted for short lengths of wire (pigtails) completely in the box and for wire nuts.

Most recessed "can" ceiling lights have a small box for connections off to the side of the "can". The small box usually cannot accept more than two cables each with a hot wire and a neutral wire (and a ground wire).

Just because the box has 4 slots for cables to enter does not mean you can use all of them. The 4 slots are for such situations as cables entering from the top versus entering from the bottom.
So will my situation get me burned up wires, breaker tripping, or blown bulbs?
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Old 07-11-2011, 06:51 AM   #6
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How many wires can be tapped into a light fixture?


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So will my situation get me burned up wires, breaker tripping, or blown bulbs?
Box size versus number of wires is a code requirement.

You won't have blown bulbs and you almost certainly won;'t have breaker tripping.

If you draw the full 15 amperes with the box overcrowded y ou could get the wires to overheat although tis is very rare. More likely you would have great difficulty stuffing the wires into the box, and if you had to change something later the wires may have been bent sharply enough that they break when you unstuff them and restuff them. If the wire insulation broke when you were stuffing the wires in then you could have breaker tripping. You would then unstuff the box and run into the preceding problems.
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Old 07-11-2011, 02:44 PM   #7
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How many wires can be tapped into a light fixture?


I hooked everything up. There really wasn't an issue with room in the box, although if another cable was added there wouldn't be much room and stuffing the wires would be tough.

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