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# Connecting different light circuits together

## Connecting different light circuits together

#1
02-04-16, 08:40 PM
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Connecting different light circuits together

Hi,

I have two different light circuits in the same hallways I'd like to connect.

1. Lights controlled by two switches
2. Lights controlled by one switch

I'm not quite sure the right way to connect them. My gut instinct would be to connect one light from each circuit to each other and make sure they are all three way switches, but I'm pretty sure my gut is wrong

Would appreciate any insight.

Thanks.

#2
02-04-16, 08:45 PM
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What else is on those circuits?

#3
02-04-16, 09:25 PM
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I have two different light circuits in the same hallways I'd like to connect.
Do you want to get rid of the single location switch and put them all on the 3-way switches? If so disconnect the switch and power to the light on the single location switch and connect that light directly to one of the lights on the 3-way circuit.

#4
02-05-16, 05:24 AM
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For each light that you want to connect to the other circuit ... Up at the light fixture ...
... disconnect the existing switch and power wiring to the light ...
and and run a cable over to one of the lights on the other circuit and thus ...
... connect that light directly to one of the lights on the ...
... other circuit.

#5
02-05-16, 05:42 AM
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An existing single switch location can become part of the 3 way light circuit. Disconnect it from its existing wires and tape those wire ends. Run a 3 wire cable over to one of the existing 3 way switches. Label the wires of that existing 3 way switch, notably identifying the common wire. Remove that switch and put it where the single location switch used to be. Match the wire colors of the original cable when connecting the new 3 wire cable to the non-common switch terminals. Connect the other wire to the common terminal. Back at the old 3 way switch location you worked on, connect a 4 way switch, putting the original non-common wires on the dark terminals and the new non-common wires (same colors) on the lighter terminals. Connect the other wire of the new cable to the common wire of the original wiring you unhooked.

A fourth switch location can be added but the cable should be run to a 3 way switch, not the 4 way switch.

#6
02-05-16, 01:11 PM
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Thanks for the responses...I think I understand, but still slightly confused. So let me try and recap and please correct me if I'm wrong.

Also, I do want the third switch to be able to control the lights (since it's around the corner of the hall).

Lets name the circuits:

A: Two switches
B: Single Switch

I'm assuming the switches on A are 3-way, so no need to make any changes at those switches.

Steps I'll need to take:
1. Connect a light from A to B
2. Change the switch on B to be a 3-way switch

Number two is where I am a little confused, does this mean I need to run a 12/3 or 14/3 down to that switch? It didn't look like the switches on A has 3 wires (excluding ground) running to them, but I can take a closer look now.

#7
02-05-16, 02:26 PM
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You will need two 3-way switches and one 4-way switch not thre 3-way switches.

#8
02-05-16, 03:15 PM
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Does the 4 way switch need to be in the middle?

Also, can only one switch (one of the ends go up to the lights)?

#9
02-05-16, 04:06 PM
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Does the 4 way switch need to be in the middle?
So long as the wiring doesn't change it can be elsewhere but it would be more complicated to run the cable.
Also, can only one switch (one of the ends go up to the lights)?
That is exactly what the diagram shows so I'm not sure why you are asking. The output of the switch on the far right and only that switch goes to the light. The other lights are fed from that light.

Last edited by ray2047; 02-05-16 at 04:23 PM.
#10
02-08-16, 06:39 PM
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So I gave this a shot today and ran into some problems

I screwed up with my wiring somewhere, but I ran out of daylight to debug it, so would love some helpful pointers in where to look.

Currently all the two switches that don't have the power coming into them (the 4 way and the 3 way that runs to the lights) work as expected if the switch with the power is on. However, if the switch with the power is off, then these switches don't do anything.

I'll take everything out tomorrow and test the connections, but I'm not entirely sure where I screwed things up. Perhaps I didn't connect the right screws to the right cables on the switches?

#11
02-08-16, 07:26 PM
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if the switch with the power is off, then these switches don't do anything.
3-way switches do not have an on or off position. What do you mean? You did use a 3-way switch didn't you?

#12
02-08-16, 08:19 PM
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Yes, I believe both 3 way switches has 3 screws to tie into (excluding ground).

I suppose another way of describing it is when the 3 way switch with the power going into it is switched "downwards" (since there isn't technically an "on"), the other two switches work as expected. However, when the switch is switched "upwards" the lights turn off, and the other switches do nothing.

I just noticed that half the lights don't turn on as well, so something is definitely wrong.

I feel pretty defeated after today as nothing really went my way. Felt like it was one mistake after another. I'll take things apart tomorrow and try to see if I missed a wire somewhere.

#13
02-08-16, 08:57 PM
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Be sure at the first switch you have the black wire of the power in cable on the common. Be sure the 4-way is wired according to the diagram that came with it. Usually two pairs of screws such as two brass two black. Both travelers of the cable from box 1 are on the same color screw pair and travelers from box 3 on the same color pair of screws.

#14
02-09-16, 09:29 PM
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Figured things out.

My wiring was wrong on the 4 way switch (didn't have travellers going to the same color screws). Also, a set of recessed lights weren't working because the white wire came loose in one of the cans.

#15
02-10-16, 07:23 AM
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Thanks for letting us know what the problem was.

#16
02-15-16, 08:55 AM
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Hello, I just got here and I see a serious mistake. Before doing anything like this find the breaker that controls the circuit . Make sure that one and only one breaker turns off what you are working on. If not you run the risk of having 220 volts .

#17
02-15-16, 09:44 AM
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Make sure that one and only one breaker turns off what you are working on.
The diagram uses only one 120v feed to a totally redesigned new circuit. I don't see how you could end up with 240 volts unless you did something very unlikely like instead of using the two wires of a single conductor cable you used ungrounded conductors from two different cables..

Last edited by ray2047; 02-15-16 at 10:00 AM.