How Many Wires Can Be Tapped Into A Light Fixture? - Electrical - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum How many wires can be tapped into a light fixture?
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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.

07-10-2011, 03:10 PM   #2
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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

07-10-2011, 03:39 PM   #3
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Quote:
 Originally Posted by sirsparksalot 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).

 07-10-2011, 09:45 PM #4 Member   Join Date: Nov 2007 Location: Nashua, NH, USA Posts: 7,971 Rewards Points: 1,548 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. __________________ The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit. Last edited by AllanJ; 07-10-2011 at 09:49 PM.
07-11-2011, 01:41 AM   #5
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Quote:
 Originally Posted by AllanJ 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?

07-11-2011, 06:51 AM   #6
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Quote:
 Originally Posted by JayBird 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.
__________________
The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

07-11-2011, 02:44 PM   #7
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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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