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Kevin, Licensed Electrical Contractor
Category: Electrical
Satisfied Customers: 3539
Experience:  30 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License
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I was changing some light switches to a dimmer switches they

Customer Question

I was changing some light switches to a dimmer switches they were working fine then I came to one that isn't like the others. The switch had two black wires and one red. One black wire was pushed into the hole in the back and the other was on the side screw on the same end. The red wire was in the hold on by the other screw. My dimmer switch has a black and green wire on one side and a single black on the other. I originally put the black wire from the push in hole to the black wire on the same side as the green and the other black wire to the green and then the red wire to the other black wire. That didn't work, so I tried putting the black wires to the black wires on the dimmer and the red to the green and that didn't work either. None of my other switches had a red wire and they all were easily changed.
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: So far about two hours.
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: no
Submitted: 6 months ago.
Category: Electrical
Expert:  Kevin replied 6 months ago.

Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) What are the screw colors on the switch that you are changing? How many screws?

2) Does that light switch control a light from 1 location or do you have another switch that can also control the light?

3) Do you have either a 2 wire lead AC voltage tester (a contact type) or a multi meter to check the voltage at the switch?

4) If no tester available, what is the color of the hot wire connection at the light fixture? Black or red?

5) A green wire is a ground wire and only gets spliced to another green or bare copper ground wire. Green wires never get spliced to black or red or white wires.

Customer: replied 6 months ago.
The switch I removed had two silver screws. The dimmer switch I am installing doesn't have screws it has 3 wires, 2 black and one green. The switch is the only switch for that light. I don't have a voltage meter, but I think the hot wire is red. I have two black wires and one red.
Expert:  Kevin replied 6 months ago.

Thanks for the replies.

1) OK, you have a single pole switch and a single pole dimmer.

2) You need to always have a multi meter readily available whenever performing electrical work. Home Depot or Lowe's sell good meters for less than $25.00.

3) Since no meter available, I'm taking a guess that 1 black wire is the hot circuit feed and the 2nd black wire is feeding another wall switch or nearby receptacles. The red is probably the switched loop wire that extends to the light.

4) Splice the 2 black house wires together along with 1 of the dimmer black wires. Splice the house red to the other dimmer black.

5) If the box contains a bare copper ground wire, splice it to the dimmer green ground wire. Or if the wall box is metal, terminate the dimmer green ground wire to the metal wall box using a green ground screw.

Reply back to me and let me know if the dimmer is working correctly. .............Thanks..............Kevin:)

Customer: replied 6 months ago.
Ok thank you. I will get a voltage meter before I go further just to make sure.
Expert:  Kevin replied 6 months ago.

Shown in the link below is a good meter sold at Depot for $23.00. Lowe's also sells similar meters for approx the same price.

Yes, better to have a meter readily available to confirm the hot wire rather than guessing.

Let me know how you make out and we can take it from there if necessary.............Thanks.............Kevin:)

Expert:  Kevin replied 6 months ago.

Hope this helps………If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.


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