I am replacing a few switches in my kitchen. I am a bit confused on a couple of my switches. I attached a picture that hopefully can help. This is a 4 gang box with 2 3-way switches on the outsides, and 2 single pole switches in the middle. My question is on the 2 single pole switches, they each have 3 black wires going to them. One switch turns on an outside light, the other is a mystery to us, we have tried to figure it out for years but no luck. I'm assuming 1 is the hot wire, and 1 goes to the light, but the third black wire is connecting to the adjacent switch. Can anyone explain this to me? On my new switches i'd rather just use the two screws and not any of the pushins. Why are 3 wires being used?

 

Welcome to the forums.

It's proper to connect the two wires together and run a tail out to the switch.

However, many people find it easier to grab power where they can and that means just connecting to the available terminal at the device.

In your case.....there should be a single tale left for each device.

 

The switch is being used to connect the two wires instead of a wire nut and a pigtail. One is power in and the other is power out to the next switch.

 

So your saying the switch that was in question as to what it operated, is basically a dummy switch and supplying power to the other switches? Just to clarify if it isn't clear from the picture, the switch in question is the 3rd from the right, and it has one black wire going to the switch to the right of it, 1 to the left of it, and the third is coming from panel I assume. Should I correct this when replacing the switches? Thanks for your help.

 

No. It is a functioning switch providing power to whatever is connected to the screw that has a single wire. Take the two wires on the same terminal off and connect together and to a six inch length of black wire(pigtail) and connect the pigtail to one screw of the new switch.

 

The black wires that are by themselves are the loads. One is the outside light and we don't know what the other one is.

Of the two black wires that are together on each switch, one of the wires in each pair is the switch-to-switch jumper. The other wire on one switch is the power in from the panel. On the other switch, it is power out to another load.

Tag the two load wires and remove them. Remove the other four wires. Stick the jumper wire in your pocket for a second. Cut and strip a new black pigtail, from wire that is the same gauge as the wires on the switches now. Splice the two wires that are still in the box, the new pigtail and the old jumper in your pocket together. That will give you two pigtails off a power-in power-out splice. Connect each pigtail to one of the terminals on each of your new single-location switches. Connect one of the tagged load wires to the second terminal on each of the new switches.

You will still have a mystery switch.

Tech Note: This is a 4 gang box with 2 single-pole double-throw switches on the outsides and 2 single pole single-throw switches in the middle.