It shocked the #$!%&! out of me. Why? - Woodworking Talk

rocklobster · 08-16-2009, 03:38 PM

I found a small crack in a weld in the cyclone I bought recently so, feeling confident in the 21 hour arc welding class I took two years ago, I decided I would fix that. I installed a 220 outlet for the welder in my shop. The shop has 60 amps running to it and the welder takes 50, so I shut everything off (but I did forget the dusk-to-dawn light out front because it wasn't shining).

I pulled the cyclone out into the gravel driveway in front of the shop.

When I couldn't strike an arc, I remembered to put the ground clip on the work piece. I got it going and proceeded to melt a hole bigger than the crack I was trying to weld. I looked for something to patch the hole with, but couldn't see because of a glaring sunburst in front of my face regardless of which direction I looked.

I switched my auto-darkening helmet to ON.

So I found a small piece of 16 guage steel to match what I'm welding and put that on there. I turned down the amps and turned out some of the most beautiful beads ever seen by someone who has...well... never seen a bead before.

I turned off the welder, left the ground clip on the work piece, left the electrode in the holder and laid it on the driveway. I went into the shop to look for my slag hammer and, when I flipped on the light switch, BAM! I got a good zap. The lights came on but the GFCI switch kicked off all the receptacles.

When I unplugged the machine and reset the GFCI, everything was fine. Why did I get shocked?

I'm a little worried because my dust collector is coming soon and I plan to use that 220 outlet for it. Any ideas?

Thanks,
Rob

woodnthings · 08-16-2009, 05:09 PM

A bam would indicate a live wire touching the switch plate. (You didn't state whether the switch plate is metal or plastic) A zap would indicate a static shock. I don't think the welder has anything to do with it since the ground clamp was still attached and the power was off. However, you should make certain that your neutral wire on your 3 prong 50 amp, is securely grounded in the panel and that your panel has a good connection to the grounding rod outdoors. Also are you using Romex or thinwall conduit to run the wires? Check the switch box for a hot wire touching somewhere, but that would trip the breaker, so that's not likely here. Be careful Bub, what's not seen can kill Ya!

bill
FYI you might post this question on www.DYIchat.com under electrical and see what the master electricians have to say about it.

rocklobster · 08-16-2009, 05:53 PM

A bam would indicate a live wire touching the switch plate. (You didn't stae whether the switch plate is metal or plastic) A zap would indicate a static shock.

Though the switch plate is plastic, it definitely felt like a 110 volt shock. I've felt it before when wiring a light switch and forgetting that I left the power on.

you should make certain that your neutral wire on you 3 prong 50 amp, is securely grounded in the panel and that your panel has a good connection to the grounding rod outdoors.

I'll take a look at that.

Also are you using Romex or thinwall conduit to run the wires?

Romex.

I'll take another look at the wiring, but I took a 21 hour course on that, too, so I'm sure it's in good shape.

rocklobster · 08-16-2009, 06:19 PM

Could this be the problem? I put the breaker on the right side, but grounded it on the left side.

After a second look, I see that the left side is the only place for ground wires. Is the neutral wire for the 220 breaker in the right spot?

woodnthings · 08-16-2009, 06:45 PM

All the neutrals are tied together right and left, or they "should" be!

I guess I'm not understanding how you would get shocked touching a plastic switch plate, unless it was a static shock.
Let's see those welds!

bill

rocklobster · 08-16-2009, 10:19 PM

Quote:

Originally Posted by woodnthings

I guess I'm not understanding how you would get shocked touching a plastic switch plate, unless it was a static shock.
bill

I'm a little confused about that, too, but I did get shocked and the GFCI tripped. It was very humid and I was dripping with sweat, not much of a static-inducing atmosphere. I can't make sense of it.

I already ground and painted the weld, but I'll get a shot of that thing of beauty later. I'm in for the night.

Rob

woodnthings · 08-16-2009, 11:09 PM

On the switch plate. I'd really look at testing the ground on that box. Are they metal or plastic boxes? Also curious as to a GFI on a lighting circuit. Is this a dedicated light circuit or are there outlets?
Is the outlet a 15 amp wired with no 14 wire or a 20 amp with no 12 ? All this should be in proper order, but have to ask anyway. If you do any testing on this switch, turn off the breaker first. Then I'd replace that switch just to be sure. If we rule out the welder and static shock that only leaves the switch and that circuit. Good luck.

bill

Sleeper · 08-17-2009, 12:02 AM

I have many years experience as an electrician, and I'm a little confused as well. For one thing the GFI has nothing to do with this circuit. I think you have another issue going on.

rrich · 08-17-2009, 12:04 AM

Your description of the welder leads laying on the driveway causes me to suspect current from neutral seeping into the ground and causing the GFI to trip.

Sleeper · 08-17-2009, 12:25 AM

Quote:

Originally Posted by rrich

Your description of the welder leads laying on the driveway causes me to suspect current from neutral seeping into the ground and causing the GFI to trip.

The only way this can happen is if the welder is plugged into a GFI. I don’t see a GFI in this circuit.

Sleeper · 08-17-2009, 12:43 AM

It’s not the welder, but you say you were repairing your cyclone, could you have melted a wire in the cyclone while welding and was the cyclone plugged in to a 120 volt GFI at the time?

rrbrown · 08-17-2009, 12:44 AM

First off rob if you are referring to the white wire as neutral for 220V then your wrong. If you had a red, white, black and ground then yes but the way it is the white wire is the second hot leg.

Second thing is the right side where the neutral wire is attached there seems to be a group of bare wires twisted together that look to be aluminum (it may just be the picture) but if they are neutral wires they should be coated until they reach the bar. Even if it's for identification purposes.

As for the shock you got if the switch New or otherwise is shorting out when moved it could shock you and trip a GFCI. I got zapped by a brand new switch last year, they make them cheaper everyday it seams.

Sleeper · 08-17-2009, 12:50 AM

Quote:

Originally Posted by rrbrown

First off rob if you are referring to the white wire as neutral for 220V then your wrong. If you had a red, white, black and ground then yes but the way it is the white wire is the second hot leg.

You do not need a neutral wire for a 220 volt welder. Sometimes a 2 wire cable with ground is used for this and the white wire is not used as a neutral but at a hot. The other wires are from another circuit and not the welder.

The aluminum wires do look like they are being used as the neutral for this panel, but I don’t believe this can cause the problem unless it has a bad connection at the other end. I don’t believe that this panel was originally intended for 120 volt.

Handyman · 08-17-2009, 01:11 AM

Rocklobter First I would move the bare wire to the other ground block. From looking at your picture the box is a secondary panel, Meaning you are getting power from your house and feeding it into the panel in your shop. That would make the house panel the primary and the shop a secondary. With that said the secondary neutral bar and ground bar not bonded. One is attached to the panel and the other sits on 2 black insulated feet. This may not be the cause of your currant problem, but it needs to be done.

Sleeper · 08-17-2009, 01:37 AM

Quote:

Originally Posted by Handyman

Rocklobter First I would move the bare wire to the other ground block. From looking at your picture the box is a secondary panel, Meaning you are getting power from your house and feeding it into the panel in your shop. That would make the house panel the primary and the shop a secondary. With that said the secondary neutral bar and ground bar not bonded. One is attached to the panel and the other sits on 2 black insulated feet. This may not be the cause of your currant problem, but it needs to be done.

If you do this, then that 120 volt circuit will not work anymore, but also it will make that buss bar hot when whatever is on that circuit is turned on. I agree that wire should not be used as a neutral and the 120 volt circuits need to be removed with that wire. You can remove the 120 volt circuits or replace the feeder cable to the subpanel.

rrbrown · 08-17-2009, 02:15 AM

Handyman said it best, I drew a blank while trying to post until he posted. The neutral and ground wires in your main box or bonded. I assumed they were in this box but it looked suspicious. I would still change that switch because of my past experience. Like I said I had a brand new switch within the first week It popped when I turned it on and it shocked me threw the small opening around the toggle. I later had 2 others pop but no shock so I changed all switches. I bought the 10 pack box from Home depot the first time and went to my local hardware the second time. No more problems cost more but not that much more.

Sleeper if you noticed I said he had the white wire as the second leg (hot Wire) because he didn't have the red wire as in some cases. I was concerned about him calling that live white wire a neutral.

I really doubt that the 220 circuit is his problem and I'm pretty sure the switch could be.

woodnthings · 08-17-2009, 05:02 AM

The twisted aluminum is the "neutral" feeding from the house panel on the right side. The copper wire is the "neutral" to the welder outlet. If as was posted, the neutral from the house is floating and not bonded, this may be the problem as well as the switch possibly being faulty. I'd change it just to be sure with a quality one. I'd still like to know what all is on this circuit myself. Maybe Rob will chime in a show a picture of the switch and wiring and the 220v outlet and wiring and the neutral "bond" ?

bill

Sleeper · 08-17-2009, 10:51 AM

I actually do not see a ground wire that goes back to the main panel. This subpanel is definitely a 240V only box. Someone has made it a 120/240 volt panel by connecting the neutral of that `120V circuit to the bare ground. For this box to be legal it needs a 3 wire with ground (4 wires) cable run from the main panel.

I was an electrical contractor for 10 years and I cannot tell you how many times I have seen this. It is not legal but it works. Just do not move that bare aluminum wire without disconnecting the 120 volt circuit that is connected to it. With the neutral wire missing, current can back feed through the 120V circuit. I know a plumber that was killed 30 years ago when he cut a water pipe that was being used as the main ground.

I am concerned that I don’t see a ground wire big enough to be a main ground wire. The only wire big enough is the welder ground, but since its part of the cable we know that is not it. I don’t know what’s going on above the neutral buss in the photo or if there is more wires.

These panels came with either a bonding strap or a screw that would tie the neutral buss bar to the panel when the neutral buss bar was going to be used as a ground, which I suspect is the ground path for the ground bar on the left side.

Oh, Richard, I know you said it right. I was tired last night and falling asleep as I was typing, but I just didn’t want rocklobster to make things worse by moving things around too hastily.

rrbrown · 08-17-2009, 11:01 AM

Rob STOP Bill is right about needing more information and pictures.

1. Is this a separate circuit or a sub panel ?

If this is a separate circuit run to a outside building then the
ground and neutral should be separate. If it is a sub panel it
should have it's own Grounding rod at the panel and the ground
and neutral should be bonded.

2. I only count 4 ground wires with 4 circuits. Where is the 5th
ground to connect back to main panel ? Same thing on the neutral
side I can't tell. There should be 4 neutrals (3 for circuits and
one to main panel) there is no neutral on the 220 circuit.

3. I also noticed the (3) 20 amp circuits, what is the wire size and
what is on the circuit that tripped the GFI?

20 amps should be 12 gage wire?

4. The 220 circuit wire seems to be heavier gage then the feed
wire. What is the wire size and what size circuit is it on in the main
box ?

rrbrown · 08-17-2009, 11:04 AM

Hey sleeper we must have been posting at the same thing at the same time.