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-   -   Installing ceiling fixture with a metal junction box (http://www.diychatroom.com/f18/installing-ceiling-fixture-metal-junction-box-98949/)

Romanuke 03-20-2011 08:01 AM

Installing ceiling fixture with a metal junction box
 
I am installing a ceiling fixture after having removed the old fixture. The old fixture was a fluorescent fixture with no junction box. I installed a metal junction box and then installed the new fixture (which has a metal base). I keep getting faults when I turn the power back on. I have tried different things to ground the arrangment. First, I connected the bare ground wire from the ceiling to the junction box using the green grounding screw provided in the junction box and I connected the fixture ground wire to the bracket using the green grounding screw. That did not work. Then I tried tying the two ground wires together and connecting both to the bracket using the green grounding screw. That also resulted in the circuit breaker being tripped.

I tested the fixture before connecting the ground wire from the fixture and it worked fine (with the light fixture NOT connected to the bracket -- just hanging from the ceiling). It is when tried to ground the bare wire from the fixture, that I ran into the faults.

Can someone point me in the right direction?

Do I have to do anything different since both the fixture and junction box are metal?

BigD9 03-20-2011 08:21 AM

Quote:

That also resulted in the circuit breaker being tripped.


Is the actual breaker tripping or is it the GFI tripping? It would seem to me that if the actual breaker is tripping, then there is a short between the black and white wires. Maybe when you were installing the metal box the wires got scraped while being pulled through the box?

Romanuke 03-20-2011 09:22 AM

Thanks for the reply.

There is no GFI on that circuit nor at the fixture.

When I just hang the fixture (not attached to the bracket) and try the light it works fine. If the wires were damaged, I think that would cause a short as well, but it does not.

Romanuke 03-20-2011 09:36 AM

also. the wires look ok

Doc Holliday 03-20-2011 09:55 AM

New ground wire from the panel to the fixture and the ground wire connected directly to the ground wire of the fixture, removing the box from the equation.


That's what I'd try at least.

Romanuke 03-20-2011 10:06 AM

Quote:

Originally Posted by Doc Holliday (Post 613063)
New ground wire from the panel to the fixture and the ground wire connected directly to the ground wire of the fixture, removing the box from the equation.


That's what I'd try at least.

so you are saying just connecting the the two grounds together with a wire nut. Do I have that right?

BigD9 03-20-2011 01:53 PM

Please excuse me for being so dense sometimes. But it looks like to me that if the light hanging works OK, but when you touch it to the metal box it trips the breaker then one of two things is going on here. Either the box is hot, or the fixture is hot. Be VERY careful. Electricity has the nasty habit of jumping out there and "touch someone"...YOU. It seems to me that anyone who has ever worked around electricity has at least one screwdriver with ark marks on it!

I would check both items to see if either is hot before you do anything else. Good luck and report back, OK?

Romanuke 03-20-2011 02:12 PM

I just attached a very simple fixture with no ground wire itself and it is working fine. I checked the wires and the box with my voltage detector and only the black line is live.

Still confused...

Chevyman30571 03-20-2011 02:31 PM

I am guessing that when you mount the fixture to the box that you are pinching the wires on the bracket causing a dead short. that's why when you mount the fixture make sure you are not pinching the wires.

Romanuke 03-20-2011 02:40 PM

Thanks again for replying. I will try that. It is possible that there is problem with the fixture?

BigD9 03-20-2011 02:49 PM

Quote:

Originally Posted by Romanuke (Post 613238)
I just attached a very simple fixture with no ground wire itself and it is working fine. I checked the wires and the box with my voltage detector and only the black line is live.

Still confused...

Check the white wire and box with a voltage meter, Then the bare ground and box. Reading should be "0". Now check the fixture body and a known good ground. There should be no voltage.

Chevyman30571 had a good suggestion also. And yes, it very well be a problem with the fixture. If the fixture is touching the black hot wire it will make the fixture hot. When you touch it to a properly grounded metal box and it trips the breaker and is saving your life.

This setup wouldn't be controlled by a 3 way switch by any chance is it?

Romanuke 03-20-2011 03:35 PM

Before you replied, I checked the new fixture at another location where there is a ground and I know the existing fixture worked. I attached the new fixture with the ground to ground connected, and as soon as I turned the power back on there was a short and the ground wire from the fixture got zapped and broke. It was only the very thin bundled wires and not a normal copper wire. I am pretty sure its the fixture.

Romanuke 03-20-2011 03:37 PM

and to answer your other question, no it is not on a 3-way switch


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