What's going on here? (electrical)

[Theb]

I'm wasting my Saturday replacing the light switches and outlets in our 1960 house. Things have been going relatively well until I got to this one. The left switch has been pulled out. It was a three way switch that controlled our porch light. I don't know why it was a three way switch. The right switch controls an outlet.

I'm going to replace the three way switch with another three way switch and replace the other one with a regular switch. Let me know if this is a bad plan.

Red is the hot line in my house so I was surprised to see two red wires on one switch. Can someone break this down for me?

 

[DrPizza]

If you do exact replacements, you probably don't have to worry.

Re: two red wires. The color means little, but that's how switches work. You also have black and white, let's assume that the white wire is neutral - no way of knowing for certain without testing. Anyway, imagine you had a straight run from your breaker box to the light bulb - a white wire and a red wire. Now, you decided you didn't want the light on 100% of the time, so you wanted to insert a switch into the circuit. You would cut the red wire in half, and put the switch in the middle, so that the electric goes to the switch on the first half of the red wire, then if the switch is on, it comes out the switch and goes into the 2nd half of the red wire leading to the bulb.

That thing you're wondering about is called a wire nut. Again, there's no way to know for certain what you're working with, without testing the wires to see what's hot and what's neutral. But, if I had to guess, one of the wires going to that nut is bringing your electric into the box. It's the hot wire, not the neutral wire. And that nut is to split the current in two: some goes to one switch, some goes to the other switch.


[note: I tried to keep the terms understandable for the OP; yes, I realize that the wording isn't technically correct, e.g., whatever the hell "electric" is.)

 

[stormkroe]

Nooooo!!! Hehe
In this instance, the white wire (along with the black wire) is a 'traveller'. The red wire is constant power, that's why it is shared with the single pole switch.
The shared red will go on the black screw of your new switch, the black and white will go on the brass ones.
You'll notice the black and white are part of a 3-wire, the 3rd is tucked back in the box undoubtedly spliced to a black wire that goes up to the light.
Unless this is part of a 4 way switch circuit (more than 2 control points), you can verify by going to the switch on the other end and it should be a stand-alone 3 wire terminated to the switch with NO other splices. Red to the black screw, black and white to the brass screws.
As to your question about the black wire, it is constant power, either coming in or going out to another device.

 

[stormkroe]

Also, those 3 way wire look like they were just stabbed into the quick connects of the switch. Those suck, bend some hooks and put them under the screws.