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hot ground?

Posted by mom_in_wv (My Page) on
Wed, Oct 21, 09 at 0:02

I'm replacing a bathroom light/fan. I pulled the old one and found it wired with 2 pieces of 12-2 w/gr, one for light and one for fan. At first, that was all I could see. I got continuity tester. All white wires were in contact, all ground wires in contact. So far, so good. Black wires not continuous. Had son operate switches. One switch connected one black wire to either ground, the other switch connected the other black wire to either ground.

Got to the junction box nearby in attic. Very tight, old fixture box that they've packed full, no fittings where wires pass through sides. I carefully mapped all connections and moved the whole setup into a large square box with bushings to protect my wires. Kind of hoped that, if there was a short, that I would find it or relieve it.

The only change I made to the original configuration was to run light and fan off 12-3 w/gr. Got it all hooked up, power still off, and tested. Sure enough, one switch connects my red wire to the ground, the other connects the black wire to the ground.

My son is disgusted that I don't just stick the fixture into the ceiling and be done. The house was built in 1960 and it "hasn't messed up yet." I am afraid to leave two switch connections that both seem to run through my bare ground wire.

The box had 3 "regular" connections, I guess "power in" and 2 lines out. There are 2 switch lines and there were 2 fixture lines. I've changed it to one fixture line with the 12-3.

Switches are wired properly, bl & wh to poles, w/ grounds connected to green screw on each switch.

There were small wood splinters in the box that were not scorched. They looked like construction debris.

Is this safe? If not, what do I need to do? Please help!!!!

Thank you!


Follow-Up Postings:

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RE: hot ground?

I was going to tell you how dangerous using the grounding wires for other than grounding, but I'm confused. If the switches are wired properly, how are things being connected to ground. Somewhere in this circuit someone has to have connected a ground wire to a current carrying conductor or terminal on a switch. That should be easy enough to find.

Just how did you determine that the switches are connecting you to ground?


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RE: hot ground?

Maybe I'm wrong about it (I would really like to be wrong!). Looking at just one part of the original setup, there would be a black, white and copper wire sticking out of the ceiling, say for the light. I connected the continuity tester to black and white and turned on the light switch. Nothing happened, light on tester stayed off. I connected tester to black and ground. When I turned on light switch, tester lit up.

The same thing happened with the black/white/ground for the fan. The switch seemed to close the connection between black and ground, not black and white.

I did go ahead and hook up the fixture and try operating the switches. It worked perfectly. I turned the breaker back off until I could learn if this was something that requires further attention.

The connections are correct at the fixture and at the switch, and the fixture operates properly. The ONLY reason that I am worried about this connection is that turning on each switch appears to make the connection between black and ground, but not between white and ground (based on continuity tester).

I can't see the entire length of wire, so I don't know if there is another junction box between fixture and switch (seems unlikely, and both have one "old" line and one "new" line for switches - woven versus vinyl insulation on outside).

Does that make sense?

Thank you for any thoughts you might share.


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RE: hot ground?

Oops, mistake in 4th paragraph (correction in CAPS):

The connections are correct at the fixture and at the switch, and the fixture operates properly. The ONLY reason that I am worried about this connection is that turning on each switch appears to make the connection between black and ground, but not between BLACK and WHITE(based on continuity tester).


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RE: hot ground?

"I connected the continuity tester to black and white ..."

Exactly what are you using for the "continuity tester"?

A voltmeter?

A continuity tester is a small tool with its own batteries that lights up when its two leads are connected together.


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RE: hot ground?

mom: Did you connect the light black-black and white-white or did you use the ground-white? Showing voltage black-ground and not black-white is indicative of a loose neutral (white) connection.


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RE: hot ground?

"A continuity tester is a small tool with its own batteries that lights up when its two leads are connected together."

This is what I used, with 2 AA batteries. Instead of house current to light my CFL, I thought battery power would light continuity tester, but that switch would operate the same way for either.

"Did you connect the light black-black and white-white or did you use the ground-white?"

Definitely black-black and white-white. I don't hook ground wires to anything but other ground wires, or to green screws. I thought (and I'm SO obviously not an electrician!) that I never wanted to actually PLAN for current to run through a bare ground, it was a "just-in-case" (better to run through bare ground than through me!).

I'm pretty sure my hall light is one of the other lines off this bathroom fixture. I can pull it and see if it shows the same "black-ground" connection through the switch.

Sounds like I might need to check the panel for a loose neutral.

Disclaimer: I've read wonderful advice here about safety (thank you). I am a true coward about opening the panel, but have done it safely before. I kill all power to the house and wear my son's headlight, and STILL try not to touch any bare wires or metal! And nobody is allowed to touch anything electrical when I flip the power back on . . . need to leave a moment to watch for sparking/smoking before anyone makes "contact." I've added some circuits with no problems, except that I am very nervous until I see that it is all done right. I've also helped a professional electrician who worked on larger projects a couple of times here, and he seemed to feel that I had a bit of sense.

That said . . . if you think this is too big for a homeowner, please feel free to say so. But I am willing to open the panel with great caution, if that is the next logical step.

Thanks!


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RE: hot ground?

A continuity tester should not light when testing between black and white or black and ground, and if the circuit was hot when you did the test, you were lucky the tester did not blow up in your hands. My guess is you fried the tester and are getting a false reading, but if you are concerned, hire someone to check everything out.


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RE: hot ground?

IF there was any other devices (lights, motors, etc) on the circuit and turned on, you will get continuity to white and ground from the black. You are measuring through the device out its neutral wire and back to the ground connection in the main panel.


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RE: hot ground?

"A continuity tester should not light when testing between black and white or black and ground, and if the circuit was hot when you did the test, you were lucky the tester did not blow up in your hands. My guess is you fried the tester and are getting a false reading, but if you are concerned, hire someone to check everything out."

Circuit was OFF when I tested. I was looking for continuity between the wire that went out to the switch (from fixture) and came back to fixture. When switch was in "on" position, I got continuity between black and ground at fixture end, which I understood to mean that the line out to switch and back was continuous, but not on black and white, only on black and ground.

"IF there was any other devices (lights, motors, etc) on the circuit and turned on, you will get continuity to white and ground from the black. You are measuring through the device out its neutral wire and back to the ground connection in the main panel."

I have to think through this and draw pictures. I thought that measuring black and white would give me the circuit, but have to remember that switch wire goes from fixture out to switch on white, returns to fixture on black, allowing me to use THAT black wire to connect to black on fixture.

Sounds like maybe I should just test the black/white loop out to the switch and back?

Thanks!


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RE: hot ground?

IF there were bulbs in the fixtures of course there was continuity when the switches were turned on. The bulbs have a relatively small resistance (240 ohms lets say for a 60W bulb). To neutral and ground.


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RE: hot ground?

So . . . the way I was testing continuity, I effectively had TWO switches in my circuit . . . the breaker and the wall switch. When I turn on the wall switch, a circuit could be completed between black and ground; white is still separated by the breaker.

If I turn on the breaker, the circuit between black and white is complete, and the fixture operates (I just DON'T put the continuity tester up against it when its live!).

So it sounds like it is correctly wired. I feel dumb, but I was actually hoping I was mistaken about my concerns, so I'm really relieved.

Thank you for helping me sort this out!


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RE: hot ground?

The only change I made to the original configuration was to run light and fan off 12-3 w/gr. Got it all hooked up, power still off, and tested. Sure enough, one switch connects my red wire to the ground, the other connects the black wire to the ground.

This should definitely not be happening. You're only going to get limited help here based on what is understood from your description. You really need to have an electrician look at it to see for himself what is mis-wired.


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RE: hot ground?

If the circuit between the black and white was completed by the breaeker you would have ahort circuit. The hot and neutral are directly connected at any point.
White is not separated by the breaker. Only the black is opened by the breaker.

Sounds like do not even have a basic understanding of how electricity works. Maybe you not doing wiring. Sorry to be so blunt but some people just need to call an electrician.


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RE: hot ground?

"This is what I used, with 2 AA batteries. Instead of house current to light my CFL, I thought battery power would light continuity tester, but that switch would operate the same way for either."

I would strongly advise you to stop what you are doing.

Using a continuity tester in the manner you are is likely to get you burned or zapped pretty badly.

Continuity testers are not really very useful on AC power wiring, and can give all sorts of results that appear strange if you do not know exactly what you are doing.

The continuity tester can light up between black (hot) and neutral (grounded) conductors depending on what loads are also on the circuit between the two wires.

You are well past your knowledge level and are liable to be hurt.


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RE: hot ground?

I have obviously not explained my thoughts nearly as well as all of you have explained yours!

As I noted twice, I did not apply a continuity tester to a live circuit. The only reason I got it out was to identify which wire pair was associated with which switch. Having worked for years as an ER nurse, I am aware of at least one situation in which someone DID put a tester on a hot circuit. I will not fry the tester or myself!

When I checked and found black/ground continuity, I was confused. Joed's first message helped me to realize that I had a misconception about the loop I was actually testing. I would NOT find continuity between white and black, because I would NOT use the tester on a live circuit.

That was a great help, and allowed me to better evaluate the situation. Clearly, the fixture was satisfactorily wired initially. My change from a couple of 12-2 wires to one 12-3 wire IS ok, I know that.

I appreciate your concern for my safety. I will see if I can run my question past one of the electricians who has been renovating the office building we just started moving into, to confirm my understanding.

I wish I were better able to explain myself, but I am very pleased to know that the wiring that I've been living with since 1995 is probably in pretty good shape. I'm actually pleased that the old wiring includes the bare copper ground wire . . . my parent's old house was knob-and-tube!

Thanks again.


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RE: hot ground?

"I would NOT find continuity between white and black, because I would NOT use the tester on a live circuit."

Depending on what the LOADS on the circuit are (even if the circuit is OFF) you can easily find continuity between a black and a white wire.

After 40+ years working on wiring, I do not even have a continuity tester in my tool bag, and would be hard pressed to even find one in the 'junk drawer'.

Continuity testers are only useful in finding shorts and opens in clearly defined circuits.

As noted above, you tester may even light on a circuit that has a light bulb present between black and white.

You are WAY over your head. (sorry)

Go purchase 'Wiring Simplified' (Black & Decker) and read it carefully.

There are regretfully only a very few ways to do wiring correctly, and hundreds of ways to get it wrong.

Troubleshooting wiring is one of the places that even experienced electricians and engineers get things wrong.

There are all sorts of 'sneak paths' present in circuits even when they are turned off like the night light in the upstairs hallway on the off circuit.

EVERY load plugged in and connected on the circuit is between the black and white wires.

You can try and search for every one and unplug them, but Murphy never sleeps and you WILL miss one.
It might even be the one that has either no on/off switch (a door bell transformer) or the one with a broken switch.

When real trouble shooting is required a volt-ohm meter and an extension cord are common aids to figuring out what is connected to what after disconnecting the wires from the circuit.


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RE: hot ground?

"Go purchase 'Wiring Simplified' (Black & Decker) and read it carefully."

Would this be a better choice than "Advanced Home Wiring" (Black & Decker)? That's the one I have.

I appreciate all the advice and cautions. I opened this can of worms by attempting to learn something using a continuity tester. Had I not done that, I would have pulled an old fixture and hooked the new one up to the existing connections.

Given the unanimous lack of confidence in my understanding of the wiring, it seems that this would have been the best thing for me to do. There had been no problem with the wiring to the fixture; the unit was just unattractive, outdated, and missing a cosmetic part. So the project was not to troubleshoot a wiring problem, it was to replace a fixture with a comparably wired new fixture.

Next time I will know better than to consider a continuity tester to be helpful.

Again, I appreciate all the advice and concern. It seems that the basic issue here is not to use the continuity tester if I am not able to understand the results. I very carefully mapped all the connections and transferred them to a bigger box. I turned on the circuit and the fan and light operate as expected, so I did manage to put it back the way I found it. I turned it back off because I could not fully appreciate what the continuity tester showed. Obviously, an abundance of caution, however misguided.

Continuity tester to garbage, turn on circuit, quit using flashlight for nighttime trips to bathroom.

Thanks again!


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RE: hot ground?

Even a low cost volt-ohm meter would be far more useful.

The digital units have their own problems ('phantom voltage' from the extremely high input impedance) but are very handy once you understand the phantom voltage issue.

Wiggies are a little more expensive, but load circuits enough to eliminate almost all phantom problems (unless you get to higher voltage than residential).

I was not trying to be hard on you, but would hate to have anyone get hurt using the wrong tool for the job.

The 'non contact' voltage detectors are also a waste of time.


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RE: hot ground?

Just to bring this to a bit of a conclusion, I did talk with one of the electricians here. I'm probably better at explaining when I can use gestures . . .

Anyway, he said I was OK, so I will go ahead and flip the power back on.

Thanks again . . . certainly better to be safe than sorry!


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