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-   -   Spark Connecting Ground on light fixture (http://www.diychatroom.com/f18/spark-connecting-ground-light-fixture-129316/)

RonaldD 01-08-2012 10:38 PM

Spark Connecting Ground on light fixture
 
Hello-

I have wired quite a few things in my days, but I have never seen this one.

I was wiring a large light fixture, connected hot, then neutral, then ground (I know that is the wrong order....ground should have been first).

When I went to connect the ground, I heard a large pop (like a firecracker) and saw a ton of sparks go flying.

I had the switch off, but it is on a timer and I was too slow to beat the timer, so it turned on just as I was connecting the ground.

This is a 3-way circuit with a Leviton 5-wire digital timer switch. This is a brand new house, so I have a neutral, hot, and ground - plus one additional wire for the 3-way.

However, up at the light, I just have a hot, neutral, and ground. There was a super cheap plastic fixture there before (like what you have in a garage closet) that only used the hot and neutral (ground was not connected).

Although the ground wires make a big bang with sparks when touched together, the light appears to work fine now (I turned off the switch, then finished wiring).

I don't want to run the light right now until I hear some thoughts on this. Don't want to burn the house down if this is a sign of trouble.

Does this maybe indicate that the hot or neutral wires could have a short that completed the circuit through this ground?

Thanks for your help!

Ron

TarheelTerp 01-08-2012 11:10 PM

Quote:

Originally Posted by RonaldD (Post 816979)
(I know that is the wrong order....ground should have been first).

I had the switch off, but it is on a timer and I was too slow to beat the timer, so it turned on just as I was connecting the ground.

Learn your lesson?

Quote:

This is a 3-way circuit with a Leviton 5-wire digital timer switch.
This is a brand new house, so I have a neutral, hot, and ground - plus one additional wire for the 3-way.

However, up at the light, I just have a hot, neutral, and ground.
I don't want to run the light right now until I hear some thoughts on this.
Thoughts on what?

Quote:

Does this maybe indicate that the hot or neutral wires could have a short that completed the circuit through this ground?
That is what meters are for. Check.

hth

Jdizzle 01-08-2012 11:14 PM

Never work anything hot.

Missouri Bound 01-08-2012 11:14 PM

...what's a garage closet?

Jdizzle 01-08-2012 11:20 PM

Keyless fixture!

Missouri Bound 01-08-2012 11:25 PM

Quote:

Originally Posted by Jdizzle (Post 817026)
Keyless fixture!


Oh I see...."garage / closet". Punctuation actually means something. You're pretty quick on the answers dizzle.....

Julius793 01-09-2012 12:10 AM

Use an amp meter to check if threre is any amperage on the ground. Spark should never be flying on the ground! Keep in mind if there's a ground fault doesn't have to be by that box it could be else where.

dmxtothemax 01-09-2012 04:57 AM

Whilst in an ideal world there should be no currents on the earth line,
How ever in real life, there quite often is currents.
Some times they are only low currents,
But best check it with a meter,
or even a test lamp.

AllanJ 01-09-2012 08:23 AM

With the two ground wire ends still separated, measure the voltage between them with the light switched on and again with the light switched off. Report back.

To see if the hot wires somewhere in the fixture are shorted to the frame of the fixture.

joed 01-09-2012 08:33 AM

Is this a metal box? Is the ground connected to the box?
Sounds like the hot wire is shorted. Either to the fixture or the box(if metal). Turn off the circuit (at the breaker not the switch) and use a meter to find the short. You should NEVER have current flowing on a ground wire.

RonaldD 01-09-2012 08:19 PM

Thanks to everyone for all the suggestions. I am going to switch off the breaker and do some continuity tests to see if there is a short. I will let you know what I find.

Thanks!
Ron

Speedy Petey 01-09-2012 09:30 PM

Quote:

Originally Posted by RonaldD (Post 816979)
This is a 3-way circuit with a Leviton 5-wire digital timer switch. This is a brand new house, so I have a neutral, hot, and ground - plus one additional wire for the 3-way.

Explain this a little better. What wires are in the switch boxes and how are they connected? Better yet, snap a pic.

I have a suspicion that there is a switch loop somewhere and the timer needed a neutral so the genius installer used the ground for it. This would do exactly what you are describing.

fa_f3_20 01-10-2012 08:58 PM

Quote:

Originally Posted by Speedy Petey (Post 817957)
I have a suspicion that there is a switch loop somewhere and the timer needed a neutral so the genius installer used the ground for it. This would do exactly what you are describing.

Sort of related: Some years ago, I was setting up some workstation computers in a NASA facility. I had a workstation with a 27" CRT monitor positioned next to a pillar in the room, and depending on how I turned the CRT, I got big-time distortion from the pillar. The facilities engineer came by to see how we were doing, and I pointed at the monitor and said "There must be a lot of current running through the wiring in that pillar." He looked at me funny and said, "There's no wiring in that pillar!" :eek: Turned out that in another part of the facility, there were a bunch of old light fixtures where the original electrician had not bothered to run a neutral; he had just connected the fixture neutral to the box ground. There were all kinds of currents running around through the structural steel.


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