Ask Me Help Desk - Hot ground?

I was adding a new switch in a 3 gang box in a newly wired kitchen yesterday. I had not yet switched off the breaker and was prepping the wires that were previously roughed in. I pulled out the grounds nutted together for the 2 already hot circuits and felt a tingle... not a big hit but a shock nonetheless. I put a meter on the ground to the neutral a read 112 volts. The box has the following conductors.
1. 12.2 feed from junction box in attic.

2. 3 way switch for 6 fluorescent ceiling cans, black feeder pigtailed to common, white to white on feed, ground to ground feed, 14.3 2 travelers to other switch, white to feed white, grounds all tied together. Works properly.

3. 3 way switch wired same as above for over sink light. Works properly.

4. New circuit is sp swtch feeding undercounter lights.

I removed the nut on the grounds and separated them. The fluorescent can circuit is the one with the hot ground.
Its only hot when the lights are in switched on. When I disconnect the nuetral the lights go out. I did not measure the amperage on the gound. Is this an issue with one of the transformers or a bad connection? What should my next step be?

Thanks,

Jeff

It seems to me like you got a tingle off the neutral wire. The fact that you got a voltage between the neutral and the ground shows a difference of potential (Voltage), most likely on the neutral. If the ground wire had potential (Voltage), you most likely would have read closer to a "0" reading on your meter because you would not have had a good reference to ground, which is what your meter does when it reads voltage. (120 potential - ground "0"= 120V... / 120 potential minus 120 potential ground = "0" metered voltage) ie: when you meter voltage, you are referencing one point to a potential (voltage) and the other to ground (earth/ zero potential). The only time you will receive a shock off the neutral is when a load is switched on. If you switch off all of your loads, you will find that you will not get a voltage between ground and neutral. This is because both are a zero potential point. They are essentially the same point. The only difference is code says that neutral wire are current carrying, and ground wires are not (under normal operation). I have seen in very rare cases, a ground being used as a neutral, by accident. This was only because the case scenario was incorporating a three wire system with an existing two wire system (old days). The idea of a ground wire is to have all of the metal parts in an electrical system to be "bonded". This would provide a path for current flow uninterrupted until the safety device (breaker/fuse)tripped out the circuit before it could do any harm to a user. If your system ground was not functioning, you would not have anything electrically functioning in your house, so obviously you have a ground.

To put it in a nut shell... you probably touched the bare neutral coming from the light and touched the ground (or the neutral) coming from the feed. That would give you a jolt. If that's the case, every thing is probably wired up right.

In essence, when the switch is in the on (closed) position the unconnected neutral from the light becomes "hot" and is looking for a path back to ground and your hand completed the circuit via the feed ground wire!

Sounds like the switch leg is shorted to ground(greenfield?)open fixture, remove hot from ballast in, if the ground still goes live when you switch back on, that switch leg that goes to light is touching ground, pinched, or a bare spot on the wire, a nail could be touching hot and ground.

This is incorrect:

Quote:

Originally Posted by buzzman

If your system ground was not functioning, you would not have anything electrically functioning in your house, so obviously you have a ground.

If the system neutral was opened, the 120 volt devices may not work, and on the other hand, they may, due to unintentional grounds.

But if the system ground was broken, the home would continue to operate.

Keep in mind, the utility also grounds the neutral out at the pole/transformer, and often run a neutral/ground between pole to pole to insure their neutral is grounded. The home's system ground is supplemental to the utility grounding.

This only affect the operation of the system neutral. There are many homes wired circa 1950 that used a two wire Romex cable, the entire home, every light and outlet, without an equipment grounding wire, and all works just fine.

This is entirely incorrect, under the condition of all wiring is connected properly:

Quote:

Originally Posted by Erich

To put it in a nut shell... you probably touched the bare neutral coming from the light and touched the ground (or the neutral) coming from the feed. That would give you a jolt. If that's the case, every thing is probably wired up right.

In essence, when the switch is in the on (closed) position the unconnected neutral from the light becomes "hot" and is looking for a path back to ground and your hand completed the circuit via the feed ground wire!

There should never be a shock hazard coming in contact between a neutral and an equipment ground, or any grounded surface, in a properly wired system.

However, if the neutral wire at a box is disconnected, for some reason, and the load the neutral serves is energized, 120 volts will be read across the neutral and ground.

This makes the most logical sense, as one possible reason:

Quote:

Originally Posted by Stratmando

Sounds like the switch leg is shorted to ground(greenfield?)open fixture, remove hot from ballast in, if the ground still goes live when you switch back on, that switch leg that goes to light is touching ground, pinched, or a bare spot on the wire, a nail could be touching hot and ground.

Another reason may be you have is a hot neutral, due to a poor connection,or broken.

Or the ballast is defective, and the equipment ground back to the panel is defective also.

What needs to be done is test all the wiring to determine exactly where the fault voltage is coming from.

You can test across any neutral to ground in the home to check for zero volts, or no more than 2 volts.

You can test across the equipment ground, and the neutral, to a known grounded surface, such a metal water line, possibly back at the incoming service or a ground wire at the panel.

Check or change the cable that feeds the light fixture for fault, as Strat suggests.

Get back with the results or any further questions.

Agreed, and if the ground was intact, the breaker should have tripped.
This is only indicating no ground between breaker panel and light. Other grounding is probably OK and would have no affect. I understand ground wire open and that is how you determined a short, without tripping breaker.

Quote:

Originally Posted by tkrussell

This is incorrect:

There should never be a shock hazard coming in contact between a neutral and an equipment ground, or any grounded surface, in a properly wired system.

However, if the neutral wire at a box is disconnected, for some reason, and the load the neutral serves is energized, 120 volts will be read across the neutral and ground.

I don't mean any disrespect kt, you do have much more experience than I do but isn't 120 volt reading between the disconnected neutral wire and ground a shock hazard?

I assumed the neutrals were open cause he said he was adding to an exsiting box, I also assumed that if the ground became energized the breaker would have triped. I guess I assumed some things that maybe I shouldn't have.

Quote:

Originally Posted by jeffrow

I was adding a new switch in a 3 gang box in a newly wired kitchen yesterday. I had not yet switched off the breaker and was prepping the wires that were previously roughed in. I pulled out the grounds nutted together for the 2 already hot circuits and felt a tingle....not a big hit but a shock nonetheless. I put a meter on the ground to the neutral a read 112 volts.

Again, I mean no disrespect Im just trying to save face and felt like my information was regarded as completely incorrect. I can tell you from experience that a neutral (white wire ) can give you a jolt given the neutrals are opened up in a box. I remember the day I got first got bit by a neutral, I was dumbfounded on how that could happen. Maybe I should have said " previously wired correctly" instead of "wired correctly." I digress.

If a neutral is separated, it will only be live if a load is in place to provide a return path through the neutral. Unscrewing bulb or removing load will keep that neutral from being live.

You did not state that this would occur if the neutral was opened, and I qualified your answer with that explanation.

Your answer implied that at anytime there is 120 volts between a neutral and ground at all times, which is not the case.

If something is assumed with an answer the words need to state that to avoid any confusion.

Thanks... you've given me a lot of help here. This weekend I'll start pulling each of the cans for a quick check. I think the ground to the panel is worth checking also. I'll post results

The short is on the wire between the switch and the cans, that is why it only goes live when the switch is turned on, if you have several lights, separate in the middle to see if short is one half of the lights, or one of the other half lights.
You should not have "amperage on the ground", unless there is a short to ground.
If the grounds are not intact to the panel, the breaker may not trip if there is a short between a hot and a ground.