Single switch with red wire?

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Old 09-25-20, 02:15 PM
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Question Single switch with red wire?

I wanted to replace my outdoor floodlight switch with an interval timer so I could run the lights a number of hours at night. I was expecting to find a normal single switch when I removed it from the junction box, but instead found a three wire switch. There is a black, white and red wire connected to the switch. There is no other switch on this circuit nor is there an outlet controlled by this switch. One possibility is that there was a second switch outside of the house at one time and when the previous owners put aluminum siding on the house, they covered the switch up for some unknown reason....but I have no way to know if that is true. And if that is true, I have no idea what they did with the wiring.

I then looked inside the light fixture box to see if there was a red wire. I saw white wires connected to white, black connected to black and then one extra wire which looks white which is capped off...this wire could be red with the color worn as the house was built in the 1940's. So maybe the red wire was just an extra wire which was not used- but if that is true why would it be attached at the switch?

Pics are attached. Wires at the switch are labeled with color names as the pic does not show the colors well (but they are clearly seen in real life).

Any guesses as to what the red wire is about? Is there some way to figure this out?
The timer I want to attach is for two wires only. I am now thinking attaching it to this setup may not be possible.



 
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Old 09-25-20, 02:30 PM
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Welcome to the forums.

There is a chance the other half of that three way circuit got disconnected. There definitely was a second switch. The switch in your picture is a dead end three way switch. That means there is no line or load connection in that box.

You could connect a timer there using two wires from the switch. One would be from the dark colored screw and one of the others. Only two wires will do anything the third will act dead and can be capped off.

Since you don't have neutral in that box..... you must use a timer that specifically says doesn't need a neutral wire.
 
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Old 09-25-20, 03:39 PM
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PJmax, thank you for your reply and explanation!

To clarify, when you say use one wire from the "dark colored screw," do you mean use the black wire (currently connected to the brass screw) and then either the red or white wire with it?

The timer I bought states, "no neutral required" on the box so I am good with that- but thank you for pointing that out as I wasn't thinking about that.
 
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Old 09-25-20, 04:39 PM
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It could be black. There is usually a dark screw and two lighter screws.
Shorting only two of the wires will make the lights come on. You can try experimentally too.
 
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Old 09-25-20, 05:47 PM
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Many thanks again! I will get back to work on installing the timer tomorrow. I appreciate your help.
 
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Old 09-29-20, 11:52 AM
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In case anyone is curious as to the end of this story...

I was able to successfully hook up the timer and it is working. I needed the black and white wires. I capped off the red wire. The location of a possible second switch is still a mystery and probably will remain that way!
 
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Old 09-29-20, 01:14 PM
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Good job. Make a mental note of an additional hidden three way switch.

If I was at a customers.... I'd either put a brief note in the box or
write on the plate.... One of two 3w switches.
 
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