[hollycrj]

We had a fluorescent light fixture in our kitchen that needed replaced. The original one had 2 ballasts and the new one has 1. When the original one was taken down we did not mark what wires were connected to what (won't do that again ). Now when attempting to install the new one it keeps tripping the breaker.

There are 3 sets of wires coming out of the box on the ceiling. All three contain 1 black, 1 white and 1 ground. We have 3 light switches in our kitchen so we assumed that each switch has 1 black, 1 white and 1 ground. So we took all 3 black and connected it to the 1 black from the new fixture and did the same for the white and the ground. Now when we turn on the breaker the light will come on but when we flip a switch it goes out. Also when it goes out the light in our adjacent living room goes out.

We've been able to connect it so the living room light stays on, however the new kitchen light does not go off.

We have not yet took out the switches to take a look what wires are there...I was hoping that someone has come into a similar situation and could lead me in the right direction.

Any help would be great!

 

[mpoulton]

One of those cables in the box is a switch loop. You'll need to figure out what those cables actually go to. Turn off the power and disconnect everything. Leave the black wires in a safe position with wire nuts on them. Turn the power back on and use a non-contact tester to determine which black wire is hot, then turn it off again. That cable is your incoming power. Now use a continuity tester to check between the black and white wires in each of the two remaining cables. One of the cables should show continuity between black and white only when the switch is turned on, not when it's off. That cable is your switch loop. The remaining cable probably goes to other lights or receptacles. We will call it "outgoing power".

Now, connect the incoming black wire to the outgoing black wire and also to the white wire of the switch loop. Connect the black wire of the switch loop to the fixture's black wire. Connect the incoming, outgoing, and fixture white wires together. That should work.

 

[kbsparky]

You have managed to take your switch loop, and connect it as a hot feed. Turning "on" any of the switches is now a dead short circuit, and will trip out your entire circuit!

You will have to disconnect all 3 sets of wires, and then determine which ones are the:

Power feed in
Power feed out
Switch loop

Here is how to do it without using any testers:

Separate the 3 bunches of wires, and then pick one and connect it to your light. Only one of them will cause the light to work.

Once identified, then pick another set and connect it together with the first set and see if the rest of the circuit is restored. IF so, then proceed with the next step, if not, then switch to the remaining set so that your entire circuit is operational again.

That leaves one set of wires remaining which is the switch loop.

To connect it properly, take the WHITE wire and connect it to the other 2 black wires with a wire-nut. Do NOT connect any of the fixture wires to this bundle.

The black fixture wire connects to the LONE black wire of the switch loop. The white fixture wire connects to the other 2 white wires of your feed-in/feed-out bunch.

That should restore all to as before.

 

[AllanJ]

(snip)

Here is how to do it without using any testers:

Add here: Flip the switch to the off position and leave it off until the wiring is reassembled.

Separate the 3 bunches of wires, and then pick one bunch and connect it to your light. Only one of them will cause the light to work.

Once identified, then pick another set and connect it together with the first set and see if the rest of the circuit (not counting the new light) is restored. IF so, then proceed with the next step, if not, then switch to the remaining set so that your entire circuit is operational again.

That leaves one set of wires remaining which is the switch loop.

(more; snip).

(I made a note in red. This is to keep the breaker from tripping again.)

 

[joed]

The cable you have left after getting the two lights on is the switch loop. Remove the black for the fixture from the other black and connect it to the black for the switch. Take the white for the switch and connect it to the black where the fixture was. Take the white from the fixture and connect it to the remaining whites. It might already be connected there if the light was on.

 

[Brandon99212]

One of those cables in the box is a switch loop. You'll need to figure out what those cables actually go to. Turn off the power and disconnect everything. Leave the black wires in a safe position with wire nuts on them. Turn the power back on and use a non-contact tester to determine which black wire is hot, then turn it off again. That cable is your incoming power. Now use a continuity tester to check between the black and white wires in each of the two remaining cables. One of the cables should show continuity between black and white only when the switch is turned on, not when it's off. That cable is your switch loop. The remaining cable probably goes to other lights or receptacles. We will call it "outgoing power".

Now, connect the incoming black wire to the outgoing black wire and also to the white wire of the switch loop. Connect the black wire of the switch loop to the fixture's black wire. Connect the incoming, outgoing, and fixture white wires together. That should work.

Thank you for your step by step instructions. I fixed my problem