Shock... Need Advice

[CornDog]

I recently had a 30x50 shop built (pole barn style). I am currently wiring the whole shop. Since I am not a professional electrician, I am keeping it very simple. Even though I took a couple semesters in high school (18yrs ago)... it has been a while... so have been doing A LOT of reading over the last couple months.

I have six 8ft fluorescent light fixtures (each holds T8 bulbs) with residential ballasts... which pull about 1 amp each. I am using #12 wire and they will be on a 20amp breaker. I know that it a bit of an overkill, but I'd rather have plenty of room to expand, than not enough.

I have run all of the wires back into the breaker box, wired up the lights, and wired up the switch.... and kept it VERY simple. Since I am OCD... and can sometimes be impatient, I just had to check behind myself and see how it works. I do not have service to the shop just yet, so I just ran a long extension cord from the house (thats where my impatience kicks in). I know it sounds redneck, but I temporarily added a plug in just to test it out. I plugged it in, turned on the switch, and everything worked as it should... so I was happy. But when I went to turn the lights off, I rested my hand across the switch cover and the metal garage door track... and got a tingling shock. Since my house was built in 1940 and that is where the extension cord was plugged in, I figured that the receptacle was not properly grounded. I checked, and it was... but I found where the extension cord had a broken ground. So I fixed that, and thought maybe that was the problem. I checked it again, and it still shocked.

Now, since I was being impatient... is it okay to assume that I was getting shocked because I still have not grounded the breaker box or the building yet? Or could it be something else... and I should have not been shocked to begin with? Even after I finish the rest of the wiring, should I jump a ground strap/wire from the track frame over to the conduit... since they're so close to each other?

Sorry this is so long and drawn out. Just wanted to make everything clear. Thank you for your advice and for your time!!!

Justin

 

[JoeFin]

Yep - your ckt ground had to run all the way back to the house and to the main panel to find earth - while you were standing on it and touching a grounded metal building


PS: you might want a few more fixtures then that for working on cars

 

[CornDog]

Thanks for the comment. The way you explain it makes sense... And makes me feel a lot better. When I took the pictures of the lights, the camera made it look darker than it really is. It's actually pretty bright. But with plenty more available amps on the circuit (before I hit 80%), I can always add more. Here is a picture of the car in the lights. The black car in the picture does not even have lights over it yet, and it's lit up pretty well.

 

[MrMark]

You shouldn't be getting shocked. There is something wrong. The ground should have nothing on it except fault current.

 

[MrMark]

It is possible that you have significant current literally flowing through the earth (which you shouldn't) from your house panel at the neutral/ground bond. This current is seeking its way back to the transformer. You then interposed yourself between the current flow through the earth and the switch which is in contact with the earth by virtue of the metal building sitting on conductive concrete. You may have essentially been a part of the return path for this stray current.

It's the same reason people pulling water meters sometimes get shocked, although there parallel path return current is flowing on metallic piping. Here, parallel path current would literally seem to be running through the dirt.

I would check the quality of your service neutral.

 

[teamextreme]

MrMark is correct by stating that something is wrong, not just the fact that the ground is missing. If the ground was in place you wouldn't get shocked, but that is because the ground would do it's job and trip the breaker. My guess is you have a short to "ground", ie: building steel, somewhere in your installation. Hook up the ground wire from your temp cord and I bet the breaker trips. You need to start trouble shooting where your short is. Somewhere a hot wire is touching steel on a fixture or box. I would start by looking at the switch as those handy boxes are very tight and getting a ground wire touching the hot is not difficult to do.

 

[Stuart in MN]

My guess is the hot and neutral connections are swapped in the receptacle where you plugged in the extension cord.

 

[Eriehunter]

You may have a pinched hot wire up in one of your light fixtures, in the switch box or another junction box and there isn't a good enough ground to trip the breaker because of the long distance.

 

[Falcon67]

Also check the boxes and make sure than when you folded in the wires a copper didn't work it's way next to a hot screw, either in an outlet or switch box. Been there, shorted that.

 

[JoeFin]

OK guys -

I think we are misinterpreting the Op's message here

But when I went to turn the lights off, I rested my hand across the switch cover and the metal garage door track... and got a tingling shock.

He didn't say "Happy Dance Shock" or "Bounced of the wall shock" he described it as a "tingling shock" which tells me it is more along the lines of induced current rather then a circuit popping current carrying conductor to metal kind of shock.

 

[Gerald O]

Maybe the building and/or outlet box are not properly bonded to the local ground? Does the building have its own ground? I can't tell from what you wrote.

Electrical current will take all available paths, not just the best one. The current will be divided based on the resistance values of each path. In a normal 120 circuit the current path is between the hot and the grounded conductor. If the box is not properly bonded to a good local ground, but is bonded only to the ground conductor going back to the main panel, then if you complete a current path with your body between the box, which has a relatively long and somewhat resistive path back to the main panel, and the building metal which might have a very good local ground, then some of the current has to flow through you. This is why outbuildings are required to have their own ground rods and that boxes be bonded locally to that ground.

 

[zmaxmotorsports]

You may have a pinched hot wire up in one of your light fixtures, in the switch box or another junction box and there isn't a good enough ground to trip the breaker because of the long distance.

Check inside that handy box where the switch is to make sure nothing is touching the box,or anyplace else you used those boxes also.
That's just one of the resons I always wrap outlets and switches any time I use a metal box,I prefer to use the 4 square boxes with a plaster ring myself anyway.

 

[wyliesdiesels]

Agree with JoeFin about what kind of shock the OP experienced. If it was induced voltage, then the OP picked up some static. If instead, it was a 120v fault current shock, then i agree with the others that there is voltage on metal parts that arent grounded and thus it didnt trip the breaker!

We need more info to know for sure!

I got hit by fault current one time when my drill snagged in some lath wire while i was drilling holes for CATV wires in an old house. I couldnt find the cause and i got hit again a few months later touching some HVAC ducting. It wasnt until i had grounded some outlets(old house from the 30's with K+T) that i found the fault. Some of the lath wires were touching the hot terminal on several outlets. A*shole landlord didnt want to fix it, so i took it outta the rent!

 

[sberry]

Or this is missing a neutral bond connection? No pathway for a fault.

 

[Falcon67]

Could be that General Lee car - those seem to generate static sometimes.

 

[CornDog]

Thank you everyone for the advice. Over the last couple days, I have checked over a lot of stuff... in what little spare time that I have during the week. I did want to mention, the screw heads are not grounding out on the metal handy box. I taped everything up when I installed it. I brought my multimeter home from work and started at the switch. With no power connected on the circuit, I checked ohms from the switch cover over to the garage door track and got a reading of about .7 ohms. I removed the switch from the box and, as you can see, I had a reading of .5 ohms from the white wire to the box. This white wire runs to the junction box as a hot wire and is connected to all of the black wires for the lights. So I guess I need to start checking all of these wires to make sure nothing is grounding out to something... correct? Thank you for everyone's help!

Justin

 

[Farmall450]

Nice shop!

 

[teamextreme]

There's your problem. As I suspected, you have a short somewhere between the hot (white wire in your case, which incidentally should, at a minimum, be taped black, if not replaced with black or red altogether). There should be no continuity between ground (metal conduit/box system) and any hot wires.

 

[MrMark]

What teamextreme said. That meter must have been close to beeping with that small amount of resistance, essentially a short to ground. You were getting a full shock there. You need to exercise extreme caution to get this sorted.

 

[CornDog]

I had tape on the white wire and the switch just before I took the picture, but I removed it while I was checking everything. Since there are only six light fixtures and two other junction boxes on the entire circuit right now, the problem shouldn't be too hard to find. Like I said, there is no power to the building just yet, so I won't have to worry about getting shocked until I find the problem. I'll just start checking everything and let you know what I find. Maybe it will help someone else out. Thank you all the help!

Justin

 

[Gerald O]

Taping a white wire black is ok for cable, but it's against code to re-color the white when it's an individual wire run through conduit. You should replace the wire with a black or red.

 

[justsam]

If you are seeing less than 1 Ohm between hot and ground, there should be a breaker being tripped.

If it is not being tripped, I would check the main panel and be sure that the incoming neutral is well grounded. This is IMPORTANT!

 

[CornDog]

I did not know that code says the white wire could not be taped. I will go back and replace it with a black wire. Thanks!!

It was not tripping a breaker because I have not wired it to the breaker box yet. I just had the three wires coming out of the conduit (at the breaker box) and they connected directly to an extension cord. Like I said, it was just temporary to check what I just finished wiring.

Well I found my problem. In my shop, I have conduit along the walls... in case they get bumped, it will protect the wires. Well along the roof, I ran 12/2 romex. With my multimeter, I traced the to a 10ft run of romex between two of the lights. Somewhere within the romex, the black and ground wires were pinched which caused my grounding issue. I replaced the 10ft section and solved the problem. No more shock. Thanks for everyone's help and advice!!
Justin

 

[Eriehunter]

You may have a pinched hot wire up in one of your light fixtures, in the switch box or another junction box and there isn't a good enough ground to trip the breaker because of the long distance.