3 black wires to light switch

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  #1  
Old 03-31-20, 07:50 AM
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3 black wires to light switch

I have a light switch in a closet that did not work. It had the plug in attachments in the back and I had to cut the wires to get them out. The old plug had no identification as to which wire was supposed to go in which hole. Unfortunately, I did not mark down which came from which hole.

There are 3 wires - all are black, with nothing attached to the ground screw and no ground wire coming from the box. When I attached them the way it seemed proper (the fixture has 2 screws on 1 side and 1 on the other) the light worked properly but when I turn it on the other lights in the same region turn off so the wires are not attached the right way. I tried to switch 2 of the wires - but now the light itself does not turn on.

How do i tell which wire goes to the top and bottom on the right side and which goes to the left sdie so the light works and the rest of the circuit also works?

thanks,

Eric
 
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Old 03-31-20, 08:32 AM
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You need a single pole switch that will only have two screws on it. It sounds like you have a three way switch.
Two of the wire connect together and to one of the screws. The other wire connects to the second screw.
What you have is power coming in and power going out another part of the circuit and switched power to the light. You need to determine which two wires to connect to get other part of the circuit live. Then the third wire is for the lights.
 
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Old 03-31-20, 01:33 PM
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are you sure all 3 are actually black?
One of them may be white but with black tape over it....
 
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Old 04-01-20, 06:08 AM
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Hi, do you have a multimeter? you must determine which conductor is hot all the time, there must be a bundle of white conductors in the box, connect one test lead to that and the other lead to each black, one at a time, the constantly hot one will be your feed, touch it to each of the other 2 conductors, one will turn the light on, that one will go onto one terminal of the switch, the remaining one along with the feed will go onto the other switch terminal, use a pigtail for this connection.
Geo
 
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Old 04-01-20, 08:12 AM
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Joed

How do I connect the 2 wires?

I have 1 wire that is the hot wire connected to the common screw. What specifically do I do with the other 2?

thanks,

Eric
 
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Old 04-01-20, 08:40 AM
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You need a short piece of wire and a wire nut.

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There is no common screw on the single pole switch. You need a single pole switch not a three way switch.
 
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Old 04-01-20, 08:43 AM
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Take one of the other black wires and touch it to the hot wire, the one that lights the light will go on a switch terminal by itself, the other wire will get pigtailed and go on the other switch terminal.
Geo
 
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Old 04-01-20, 09:41 AM
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You have apparently a 3 way light switch “in the closet” and other lamps “in the region”??

Does the closet have a lamp?
is there a switch in the closet?
How many light fixtures are involved here?

Joed’s first paragraph tries to understand this also.
 
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Old 04-01-20, 01:28 PM
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1 switch in the closet - 1 ceiling light in the closet

The other lights are in the next room and in the hallway on the same breaker. All of the lights on the same breaker turn on individually but when I turn on this light switch the lights on the rest of the circuit go off.
 
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Old 04-01-20, 02:20 PM
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Almost enough info here to make a guess.

Guessing anyway; the closet switch should be a single pole switch, and two of the black wires should pigtail to the switch and the 3rd should wire to the switch directly. The trick, of course, is to know what two blacks should wire nut together.

I take it the current status is the inside closet light turns on the closet light, and at the same time, turns off the hall lights??
 
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Old 04-02-20, 05:09 AM
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"I take it the current status is the inside closet light turns on the closet light, and at the same time, turns off the hall lights??"


exactly
 
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Old 04-02-20, 05:25 AM
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Optimally, the closet switch needs to be changed out for a single way switch. BUT, even a 3 way switch could be wired to use only 2 screws. Your challenge will be to figure out which black wire needs to wire nut to another black wire. That will solve your issue.
 
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Old 04-02-20, 06:33 AM
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Why would a light switch have 3 black wires ?
 
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Old 04-02-20, 06:39 AM
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3 wire on a light switch, 1 is the feed in, 1 is feed out to another part of the circuit, these 2 should be spliced to a pigtail, but not always, some guy’s put 2 conductors under one terminal, wrong way to do it.
3 rd conductor would go to the device that is switched, ie light fixture or receptacle.
Geo
 
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Old 04-06-20, 04:48 AM
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add outlet

Related question:

If I am going to change to single pole switch is it possible with this wiring to change from 3 way switch to combination switch outlet with switch on the top and outlet on the bottom?

Thanks,

Eric
 
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Old 04-06-20, 05:03 AM
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It should be possible but it will require removing and rewiring the other three way switch.
Depending on the configuration it may also require some rewiring at the light fixture.
 
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Old 04-07-20, 10:27 AM
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this is the switch/outlet

Will my current wiring work with this item?

https://www.lowes.com/pd/Legrand-Whi...Outlet/3586610
 
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Old 04-07-20, 01:34 PM
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Post 1 indicated only 3 black wires in the box. So, no, you cant put in a receptacle without a white wire/neutral.
 
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Old 04-07-20, 02:02 PM
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Three black should be accompanied by three white wires. It should be possible to put a receptacle there.
Connect the black pigtail to the COMMON screw.
Connect a white pigtail to the silver screw.
Connect the switch black to the other screw.
 
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