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How To Troubleshoot An Electrical Light Fixture

How To Troubleshoot An Electrical Light Fixture
By Dave Donahue

Basic Light powered by a single pole light switch

Basic Light powered by a single pole light switch

This blog is designed to help anyone troubleshoot a light that is not working. Unfortunately at times, lightbulbs may burn out or in more difficult situations the lighting circuit may not be getting power at all. There are a number of reasons this can happen. Short circuits can cause the breaker at the panel to ‘trip’, or shut off. When this happens the possibility of a break in the wire or a loose wire at the fixture may be the root cause. Breaks in the wire or in the actual wire covering (sheathing) may cause the light to flicker on or off or trip the breaker. This means that the wire supplying power to the fixture itself may be coming in contact with metal inside the walls which conceal the wire. Normally light fixtures are wired using 14/2 NMB (or non-metallic, high temperature) wire.

To troubleshoot a faulty light fixture, first you will need to open up the switch which is turning the light on and off. You will also need to unscrew the fixture and gain access to the junction box which is feeding the light with power. Inside this junction box you should see three wires. One is a ground wire (green), a white wire (neutral) and a black or red wire.(hot) These wires should be connected to the fixture from the junction box. They may be “tailed out’ meaning the wires are connected to other wires inside the box and a wirenut will connect the wires in the junction box which may be supply the light you are working on. The tail is what is supplying power to the fixture you are troubleshooting.

Once you have determined these are connected, go to the switch and using an Ohm meter connect the two wires which are running from the switch to the light. This will be your hot and neutral. If the meter rings then you have continuity. If it doesn’t then you more than likely have a break in the wire and the wire should be replaced. If you are in fact ringing continuity then the problem may lie in the connections between the switch and the fixture. Make sure your wiring is correct. In this case, the green wire(ground) should be attached to the green screw on the switch and the black or red wire should be attached to the brass screw on the switch. Once replacing the fixture and light make sure you have seated the switch correctly in the switch (handybox) and that the terminals are not touching bare metal against the box. This in itself is a common reason many short circuits occur. Once you have wired this correctly go back to the fixture and make sure this is also wired properly.

Single Pole Light Switch

Picture of A Single Pole Lighting  Switch

Picture of A Single Pole Lighting Switch

For a basic understanding of how a single pole light switch is wired, see here. The above link shows you an easy step by step format for wiring up a single pole lighting circuit. Troubleshooting a light fixture which is not working may seem like a daunting task but it is not as complicated as it may seem.  Swartz Electric, a Colorado based electrical company specializes in lighting, receptacle, panel work and more. Last but not least always shut off all power before beginning any repair or installation! If you are not comfortable working on DIY electrical projects yourself, contact Swartz Electric for all your electrical home improvement needs.

Swartz Electric is Colorado Springs highest rated Electrical Contractor and is licensed and insured to perform electrical work throughout the entire State of Colorado. Please see our website for our licenses, insurance, and links to reviews and testimonials. In addition, Swartz Electric provides a 2 year material warranty and a lifetime workmanship warranty.

Swartz Electric – Your Colorado Springs Electrician performs electrical work throughout Colorado Springs, Monument, Black Forest, Fountain, Falcon, Woodland Park, and everywhere inbetween. We are the electricians in Colorado Springs to solve your electrical problems and meet your electrical requirements.

Call, e-mail, visit our website, or stop by our office today, and allow Swartz Electric to serve YOU.

This is an original article written by Dave Donahue for Swartz Electric. This article may not be copied whole or in part without the express permission of Swartz Electric, LLC.

© Copyright 2013. All rights reserved.

 How To Troubleshoot An Electrical Light Fixture

How To Troubleshoot An Electrical Light Fixture was last modified: April 14th, 2015 by Webmaster

31 Responses to How To Troubleshoot An Electrical Light Fixture

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  • Joe says:

    Im not an electrician by any means. I’ve just installed can lighting with existing wiring in the house. i’m adding new lighting to the existing light. We have 3 way switches, and everytime i pull a bulb out, all the lights in the string go out. Can somebody please help my incompitance. Thank you very much for any advice or help you can give me.. Take care Joe

    • Joe,
      I apologize for the delay in response. I would like to speak with you about this. What you are describing is not possible in a parallel circuit, such as can lighting. Things like these happen with Christmas lights because they are wired in series. Please call our office and ask to speak with me, and I will ask you a bunch of questions. Maybe this can all be taken care of over the phone.

      Thank you very much,
      Greg Swartz
      President, Electrical Engineer, Master Electrician

  • I have a light fixture above my dining room table with 5 light bulbs. One of the bulbs will not turn on. I have replaced the bulb with a new working bulb with no success. I then tried pulling the tab down, located inside the light socket, but that didn’t work either. Any suggestions on what I should try next to repair this problem? I also have a lighted ceiling fan with 3 bulbs but only 2 will come on. I have tried the above mentioned techniques with this light fixture too, but I haven’t found anything that works.

    A Fix-It Mom

    • Lisa –

      Thank you so much for posting your question with us! Since this is a very specific set of issues that could go in multiple directions and would require a lengthy and in-depth answer along with some troubleshooting, please call the Swartz Electric office at 719-457-2218 and ask for Greg. He has lots of questions to ask and pertinent information and we do think we can help you!


  • Tee says:


    I have a similar problem as the last individual. I have three light switches on one panel (kitchen, kitchen nook, hallway (floodlight). Two of them have alternate switches on the other side of their respective areas (kitchen and hallway). The nook only has that one light switch. I’ve checked the power to that switch and there is power. I believe that only leaves the light fixture. Any thoughts would be greatly appreciated. Thanks

  • 3 lights in one box is fairly normal.
    The 2 lights that have the ability to be switched in more than one location are called 3 way switches. Again, this is normal.
    If I understand you correctly, the last switch controls the nook area, and you have checked it, and there is power.
    I am not sure of your question. It very well could be that light fixture. I don’t know. However, it also could be an outlet that is switched (or even 1/2 switched), or it could be an unused switch capped off in one of the other lights (perhaps something that was once used as a ceiling fan and light)

    I hope that helps,
    Greg Swartz

  • Bill Bolles says:

    I have a canned lighting system in our kitchen. It consists of 4 lights all on the same circuit. One of the lights burned out, so I replaced it. The new light would not come on and the others did. I took the light down and the stem was hot. I tried the light I took down and the light I replaced it with in another light socket and they both worked. Can you identify my problem?

  • Since we know the circuit is working, I’m inclined to troubleshoot only the affected light (at least at first).
    And since we know the bulb is working, that eliminates another item.
    What the problem sounds like is a thermal overload has started to fail.

    The thermal overload is a very simple device that when gets hot enough springs apart. Over time, this mechanical device fails. Remove and replace. We can buy them at a supply house for $3.00 or so, I’m not sure if your local big box store carries them or not.

    I hope that helps.

    If all else fails, you can purchase a cheap can light and grab the overload from it.

  • James E Beecham says:

    1 of my 2 exterior wall lamps that sits aside my garage door has stopped working and it’s not the circuit breaker and it’s not the light bulb… Any suggestions?

    • Mai says:

      James –

      Consider that most of our service calls are related to loose wires. Check both fixtures to make sure that neither the wiring going out of the first light nor the wiring going to the second light is loose or separated; if all else fails you can replace the fixture itself. Beyond that, you will want an electrician to check for continuity and do some troubleshooting in order to figure out what kind of repairs you’re looking at.

      Sincere thanks,
      Swartz Electric

  • Bill says:

    I have a three bulb ceiling fixture that only two bulbs will work at one time. Doesn’t matter if I switch the bulbs, there’s one socket that won’t light. Not one socket in particular, they all work at a given time, but just two at a time

    • Mai says:

      Bill – I would check the wattage rating on the fixture if you have it available, and if not, then consider what type of lamps (bulbs) you are using in said fixture. Is it drawing too much power for the wiring of the fixture to handle? For example, if the fixture is rated for 190 Watts, that means you could safely plug in 3 x 65 watt bulbs and be fine. However, if you put in 3 90 Watt bulbs, then yes only two of them will get power due to the limitations of the fixtures ability to draw power. It could be a loose wire in the fixture, or loose prong at the socket, or a dozen other things as well. Unfortunately, it’s really hard to troubleshoot something like that from a distance.
      Please let us know if we can be of further assistance!

  • jennifer bender says:

    so i installed a bathroom light yesterday i had to put a junction box in because the previous was just thru a hole in the wall. so hooked everything up and it worked went to bed with it working to wake up and its not coming on, breaker wasn’t tripped Think i should check fixture wires first my only thought is how i did the ground wires i wrapped them around the green screw, was i suppose to cap those too?

    • Mai says:

      Jennifer –
      I highly recommend you hire a professional to troubleshoot this for you. It’s possible the fixture needs to be grounded, and not just the circuit. There’s an old adage – “That which doesn’t kill you makes you stronger – except electricity, that will kill you.” Leaving open wires or circuits inside a wall can lead to arcing, heat-resistance, and put you at risk for a fire so please don’t hesitate!

  • Gretchen says:

    I have a ceiling light fixture that is also set up to a dimmer switch. The 100W bulb blew and when replaced would not work at all.

    • Mai says:

      Hi Gretchen – I would expect that either the bulb overloaded the circuit when it ruptured, or that the new lamp is not good or is not compatible with the dimmer. Do you have any more information to help us troubleshoot this problem for you? Otherwise, your best bet is always to get an electrician in to troubleshoot this entire problem for you.

  • Joell Lynch says:

    I have a 3 light vanity fixture in my bathroom, all of the sudden the middle bulb will go out sporadically for a while, then decide to work again. The bulb isn’t blown. Any ideas on what the issue may be?

    • Mai says:

      Joell –

      I would try tightening the bulb in its’ socket (gently!). It sounds like there is a loose wire – either within the fixture, or in the wiring to and/or from the fixture, or the light socket is just not getting a complete connection. If it is a standard socket, there is a little tab or contact that is kind of springy at the very rear of the socket that might have been compacted by the wrong kind of lamp or too much force and is no longer making full contact. Remember – always deactivate an electrical circuit before working on it to prevent electrical accidents!

  • Joell Lynch says:

    Thank you so much! I will take a look (with a flashlight, haha) I did try tightening the bulb to no avail.

  • Barry Bennett says:

    I have a eln6t5wsnn524 fixture the 2 outer bulbs will not stay on please help. move bulbs and light comes on for just a second then goes back out.

    • Mai says:

      Barry – I am afraid we do not have enough information to help troubleshoot your fixture over the internet. I highly recommend you call a local electrician to troubleshoot and/or repair this issue for you.

  • Teddy Perio says:

    I recently changed all my old bulbs with LED. I have a group of 3 lights that work on the same switch but one of the three is not working after I changed the bulb. I tried replacing the old bulb and still nothing. Any help would be great!!!

    • Mai says:

      Teddy –
      I have to suspect there is something wrong with the fixture, either in its’ wiring or in the inability to support LED lamps (which pull way less power than anything else). I recommend upgrading to a LED-compatible fixture or stepping down to CFL bulbs perhaps.

  • Ryan says:

    Hello, I just installed a new vanity fixture in the bathroom. When I turn the switch on there is a noise in the switch itself, the bulbs come on very dim (there is a buzz while they are on), and then the breaker trips. The other light in the bathroom also dims-which is connected to another switch. Once I put the cover plate on for the fixture, is it possible there is metal inside making contact to the wires? I capped the wire with the provided nuts.

    Thanks in advance!

    • Mai says:

      Ryan –
      It sounds like there is a short or ground somewhere between the fixture and the switch. If I had to hazard a guess, I would think one of the wire nuts came off, or bare metal is pinched against the metal box, or that the fixture was wired incorrectly (reversed polarity, etc.), or something else is causing an open ground fault. If this is not something you can resolve easily or without confusion, then I highly recommend bringing in a licensed electrician to resolve this issue. Thanks, and have a great day!

  • john says:

    a week ago installed a digital programable timer switch in replacing a standard on off exterior light switch. lights program on at night and off at sun up working great.

    So decided to replace the two outdoor light fixtures associated with this light switch. Installation straight forward seemed easy…

    you can turn the lights on and off manually so I turned the lights on, great-feel proud of my job… lights stay on for a minute then click and they go off.

    What? hit manual on- they go on for a minute and then turn off.
    Checked bulbs for wattage in limits for new fixtures, baffled… great full for any ideas, thanks

    • Mai says:

      John –

      First, check to make sure the fixtures do not have built-in photocells for automatically turning on and off from dusk to dawn. Second – it’s entirely possible that when swapping fixtures, your hot and neutral got too close to each other and are arcing and then overloading the switch or fixture. To be honest, this is an almost impossible situation to troubleshoot online. We would definitely recommend calling a local electrician (you’re in Florida?) to help troubleshoot and repair this issue for you.

  • steve says:

    I have 4 ceiling can lights in my kitchen all on two 3 way switches one circuit They have been working fine, all of a sudden none of them turn on.Tried changing both switches and still nothing there is power going to all lights but none of them go on. I checked all the bulbs and they work . I also have a ceiling fan and light on the same circuit and it works fine so it should not be the breaker. Any ideas would be appreciated.

    • Mai says:

      Steve –

      This really sounds like you might have lost continuity – either in the load-bearing wire to the string of cans, or in the first can light. While you can try replacing the first can light to see if this resolves the issue, we highly recommend having an electrician come out to troubleshoot this issue for you since it could be more complex and may involve re-supplying power.

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