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I am a newbie with anything electrical so please forgive my ignorance. All of a sudden, my front porch light fixture stopped working. Changing the light bulb didn’t work so I’m trying to figure out if it’s the fixture, the switch or the wiring. I tried installing a new fixture but got a pop and flash and it didn’t work (it’s possible I connected it wrong since I was having trouble getting the wires connected with the wire nuts). So I just put the old fixture back in for now (nothing looks corroded on the fixture).

The box that contains the switch for the exterior light also contains a 3 way switch for my foyer light. The only thing i noticed on the switch is that the ground wasn’t connected- is that an issue? I just replaced the switch (hot, neutral and ground) and bought a multimeter. When I test between the hot and the ground on the new switch, I’m getting 120V. When I test between what I believe to be the neutral and the ground when switch is off I get 0...when switch is on, it reads 120V. When I test between the neutral and the hot, I’m always seeing 0V. I thought this was odd- isn’t there supposed to be voltage when touching the probes to the neutral and hot? Can someone clarify this for me? Thanks in advance. Should I turn off the breaker, pull off the fixture outside and flip the breaker back on and test the wires outside to see if it’s making it outside?enter image description hereenter image description hereenter image description hereenter image description here

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  • @Harper I should clarify - I did shut off the circuit breaker when I was installing the fixture. I only heard the pop when I flipped the switch on after the installation was done.
    – Dave
    Commented Dec 12, 2018 at 16:59
  • oh! Well your technique was fine then, my apologies. Visible arc flash inside a switch is disconcerting, it indicates a dead short somewhere, what event "took out" the light originally?
    – Harper - Reinstate Monica
    Commented Dec 12, 2018 at 17:09
  • I may be overstating what happened when I flipped the switch - I just don’t have any experience to know if that was significant or not. I added some pics to my original post. Thanks
    – Dave
    Commented Dec 12, 2018 at 17:19

2 Answers 2

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My obligatory "get well-rounded knowledge" statement: the scenic way is to find an accessible-feeling book on the subject and read it through. Google is dangerous, that will leave you with swiss cheese knowledge. It only answers questions, and you need a well-rounded primer to know which questions to ask.

Anyway you are on the right track. Your measurements at the switch are valuable, and normal. The reason the readings surprise you (especially re: neutral) is that switches don't use neutral. That wire is not neutral. They connect (or don't) two wire functions: always-hot, and switched-hot. Neutral is not in play on a switch, unless it's a modern smart switch.

Voltage will always be zero (ish) across a switch with a broken lamp. If the switch is on, the two terminals are both 120V. If off, always-hot is 120V and switched-hot is unconnected/isolated becuse the lamp is broken, so no voltage between them. If the lamp was working, it would pull the switched-hot line toward neutral, so you'd see 120V across the open (gapped) switch.

Powering back up to check the voltage across the bare wires outside is a reasonable next step, just be careful. 120V across them would indicate a fixture fault, 0V would reveal a wiring fault.

* most authorities think changing a light switch, receptacle or light fixture is too small a job to justify pulling a permit, so I interpret that as "too small to justify hiring an electrician", hence, handyman.

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  • Thank you for your input - much appreciated. I’m just trying to learn a few basics but you’re probably right that Google can be dangerous in certain respects when it comes to this. I added some pictures to my original post
    – Dave
    Commented Dec 12, 2018 at 17:16
  • I mis read the question, was thinking OP was measuring at the fixture not the switch.+
    – Ed Beal
    Commented Dec 12, 2018 at 17:27
  • just tested the voltage of the wires outside and they read 0V
    – Dave
    Commented Dec 12, 2018 at 17:28
  • @Dave oh dear. If breaker and switch were on at that time, that indicates a problem witheiring, possibly at a splice which is accessible. Was any recent construction done that might've put a nail through the cable?
    – Harper - Reinstate Monica
    Commented Dec 12, 2018 at 17:29
  • @Harper nevermind...I just flipped the switch on and tested the outside wires (one on the white and one of the black) and got around 120V. So does that mean there's a problem with the fixture? It looks like I'm getting 120V outside?
    – Dave
    Commented Dec 12, 2018 at 17:32
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edit - I don't think I am following the description of the problem in the question and deleted previous answer

A much more detailed description of the problem - probably with pictures - would be necessary to make any suggestions. Might be best to call in someone to look at this for you.

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  • The switch has a black and a red wire going into it - does that mean anything? So I don't have a neutral wire on the switch? I wired it the same way that the previous switch was. Should I do any additional tests? Does it seem like I have voltage going into the switch properly?
    – Dave
    Commented Dec 12, 2018 at 15:29
  • @Dave - I am afraid I may not be clear on your original description. I am going to edit my answer.
    – batsplatsterson
    Commented Dec 12, 2018 at 16:20
  • I just added some pictures
    – Dave
    Commented Dec 12, 2018 at 17:05

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