I am no electrician by any means but I have ran thousands of feet of wire, hooked up receptacles, lights, hot water heaters, breakers, etc... the average things with never an issue. I ran some new recessed lighting in a old basement. 4 lights 2 switches to be exact. I first ran a wire to each switch from desired ceiling location of first can and then the same with the other switch. Each switch is running 2 lights. 1 located in back of room one in front (so they can dim lights separately). I then ran a wire from each switch to a junction box in ceiling from hallway from here I ran a home run to main box and added a new 20 amp breaker.

I went to go hook up dimming switches and the first set I hooked up no problem... walked to the other side hook up my neutral, hot and then while I hooked up my ground it popped the breaker. I sat there dumbfounded for the better of 30 minutes trying too determine what went wrong. I hooked everything up excluding the ground and it all works but the moment the ground from the 12/2 going to light touches the ground going to the junction box it fails me. I then started further testing and found that my chirper will go off anywhere on that side of the room if near the drop ceiling rail. I know this is quite scary! Its not until I touched an old junction box in the ceiling with my hammer at the same time as the drop ceiling rail did I realize it was actually live. Ive spoke with a few knowledgeable electricians and they said it was most likely an old issue sending residual current back through the ground.

If this is in fact a great possibility then how and where do I start too look and solve this grave issue? If not, what is the next plausible issue?

Note: In new junction box I just connected black/black white/white ground/ground. In breaker there is a shared bar with both ground and neutral wires connected. Inside the can lights there is quick connectors that I cut and used wire nuts but I have rechecked this several times and everything seems correct.

  • The breaker for the circuit you were working on was off, right? Do you think the problem is with previous work, or do you think the problem is with the work you did?
    – Tester101
    Commented Aug 21, 2015 at 9:41

2 Answers 2


It sounds like there's an ungrounded (hot) conductor shorted to ground somewhere. Finding the short is likely going to be a tedious task.

Check your work

Did you install grommets or clamps, where the wiring passed through knockout holes in boxes? If not, start by inspecting the wiring where it passes through the knockouts. The edges of these holes (especially on thin recessed lighting boxes) can be quite sharp, and can easily damage cables and wires as they pass through the hole.

Check all your connections, making sure nothing came into contact with ground or non-current carrying metal. This can sometimes happen when wires are pushed into boxes, so check for loose or pulled out wires.

Inspect cables/wires where they are supported, especially where supported by metal staples or clips.

Check existing work

Start by turning off each breaker in the panel one at a time, while monitoring the voltage on the drop ceiling rails with your non-contact voltage tester. When the voltage goes away, you've found the offending circuit.

Once you know which circuit is causing the problem, it's time to start the tedious task of locating the fault. Do your best to trace out the circuit, and determine all the equipment on it. Open up all outlets and equipment, and inspect the wiring inside.

It may help to move along the circuit, and disconnect the load conductors (the conductors feeding the next junction) at each junction. Then energize the circuit, and check for the voltage again. This can help you isolate the problem, and will help you focus on the problem wiring. Once you find the offending part of the circuit, methodically inspect the wiring. Checking for damaged wiring, loose connections, improper wiring, etc.

Unless you get really lucky, you're likely in for a long tedious search. Good luck.

  • 1
    I did use grommets for each knock out hole in junction box and can lights, I know those can become sharp and cut right through a wire. I can not say for sure but I would like to say it is an old wiring issue but that might just be my pride getting in the way. I will most certainly start with turning off each breaker and seeing which one cuts off the problem which will narrow it down and help find the culprit. Thank you for your time I will report back when solution found! I appreciate your expertise!
    – FreeAppl3
    Commented Aug 21, 2015 at 13:20

Hook up your grounds FIRST

That's where you went wrong. Because it led you into "viewing the problem from the wrong perspective", thinking of your lights as having worked until you grounded them. No no, grounds are essential and a light that doesn't work with a ground is a light that doesn't work... and in fact is very dangerous.

I work in steel conduit so hooking up grounds first is mandatory by nature. This keeps me honest!

In this case you would have hooked up your grounds, turned power back on and BAM circuit breaker trip. This would reveal that part of your old circuit had a ground fault, and you could proceed forthwith to troubleshoot that, without any of your new lights being a factor.

...Or, that would pass and you'd hook up your new lights and BAM. Then you would simply divide and conquer from there: unhook half the lights, test, unhook half of what remains, test, until you narrow it down in no time!

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