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Kevin, Licensed Electrical Contractor
Category: Electrical
Satisfied Customers: 3591
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 have two lights that operate on two switches on either

Customer Question

I have two lights that operate on two switches on either side of the stairway. After I replaced both light fixtures - one is operating and the other is not. I've checked bulbs, breakers, etc. What am I missing? It worked fine before I replaced them.
Submitted: 2 years ago.
Category: Electrical
Expert:  Kevin replied 2 years ago. name is ***** ***** I will be happy to assist you with your electrical question. My goal is to exceed your expectations on Just Answer!
1) How is the 2nd light fixture wired? Is it wired in parallel to the 1st light or are both lights wired together at one of the 3-way wall switches?
2) What type of lighting fixtures are these? Incandescent or Fluorescent or LED's?
3) Are the two 3-way switches regular ON/OFF snap type of 3-ways or is one of them a dimmer switch?
4) Both lights could previously be turned ON or OFF at either one of the 3-way switches, is that correct?
Customer: replied 2 years ago.
1) Both fixtures have the standard white/black and ground.
Both switches have 2 blacks, 1 red, and 1 ground.
*Is that what you meant?*2) I'm not sure what type of light fixture the working one is (I just painted that one and reinstalled), but the non-working fixture is a Project Source fixture #0280102. They require standard incandescent bulbs.
3) They are both regular ON/OFF snap types.
4) Yes, both lights could be previously turned on at either switch at the top or bottom of the stairs.
Customer: replied 2 years ago.
Are you still there Kevin? This is my first time using this system so I'm not sure what type of delays to expect in between messages.
Expert:  Kevin replied 2 years ago.
Thanks for the replies.
1) The two switches are 3-ways. They will have 1 black screw and 2 brass screws as well as 1 green ground screw.
What is the wire color on each 3-way for the black screw?
2) Depending upon which 3-way is the switched loop (the black screw), is the wire that extends to the lights black wire. Sounds like you have a loose wire connection or a faulty splice.
3) The 2 lights can be wired in one of two different methods. The 1st light can be wired to one of the 3-ways on the black screw and then the 2nd light can be wired in parallel to the 1st light. Or the 2 lights can be wired directly at one of the 3-way switches.
4) How many house wires and the wire colors in each of the lighting fixture boxes?
Customer: replied 2 years ago.
Can you tell the answer to your questions from these photos?
Expert:  Kevin replied 2 years ago.
Thank you for the pic's
1) Both switches have a black wire located on the bottom. One of these is the hot circuit feed on 1 switch and the other switch is the switched loop wire that leaves the switch and connects to the lights. I noticed that each switch wires are terminated using the back-stab insert holes. This is not recommended as the back-stab insert holes are prone to come loose over time. It is always recommended to install wires to the side terminal screws.
2) I am unable to determine from the pics if the 2 lights are wired directly to one of the 3-ways or if 1 light is wired to the 2nd light at the 1st light fixture box. Usually, the 2nd light is wired to the 1st light. Double check the wire splices at the 1st light box. This is the most common method of wiring 2 lights. In other words, they are daisy chained from the 1st to the 2nd light. If a loose splice at the 1st light, then the 2nd light will not function. You will need to temporarily pull down each light fixture from the boxes and determine how they are connected.
3) If you can obtain an AC voltmeter or a 2 wire lead AC voltage tester, this can easily confirm the problem?
Customer: replied 2 years ago.
I should check behind the light fixture box that is working first to see if there are any disconnected wires? I just returned a voltmeter to my uncle the other day and don't have one handy.
Expert:  Kevin replied 2 years ago.
1) For now, lower each light fixture and count the quantity of house wires in each light fixture box.
If one box contains 2 blacks and 2 whites which are all spliced to the fixture black and white, then that box is daisy chained to the 2nd light fixture. Double check those splices in that box.
If the other light fixture box only contains 1 black and 1 white, then it is an "end of the run box" or the 2nd fixture. Check those splices as well.
Customer: replied 2 years ago.
Both light fixture boxes only contain 1 black and 1 white and 1 ground.
Customer: replied 2 years ago.
Could they all be spliced together at the 3 way that is working?
Customer: replied 2 years ago.
Here are some additional pictures.
Expert:  Kevin replied 2 years ago.
1) OK, then they are either both spliced together in one of the 3-way switch boxes or possibly spliced in another junction box.
2) Somehow, the 2 lights black and whites need to meet together and be spliced to form a parallel connection.
3) One of the 3-ways will contain the hot circuit feed that will have a constant 120 volts on the bottom black wire near the black screw whether the switches are ON or OFF. The other 3-way will contain a similar connection on it's black screw and that is the switched loop wire that the 2 light blacks are connected to.
4) I always recommend having an AC voltmeter readily available whenever doing electrical work. The volt meter is your best friend and most required tool whenever performing any electrical work. Working on electrical projects without a meter available is similar to a doctor not having their stethoscope readily available. Ever seen a doctor not wearing their stethoscope? Get a voltmeter from Home Depot or Lowe's as they are cheap.....around $25 and will last a lifetime:)
Customer: replied 2 years ago.
Can I go buy one and talk to you on here later?
Expert:  Kevin replied 2 years ago.
Of course, your question remains open and you can reply back to me anytime.
I'm logged on the web site every day and I can easily walk you thru the troubleshooting process if you can obtain an AC voltmeter. No need to create another question, just reply back to me like you have been doing.
Shown in the link below is a good AC voltmeter sold at Home Depot for $22. Will last you a lifetime and it is a well known brand.
Customer: replied 2 years ago.
Great. Thanks!
Expert:  Kevin replied 2 years ago.
No problem, just reply back when you are ready and I will be here.