Customer shocked by dryer

[zappy]

I tested the outlet and I got 240v. from the Neu. slot and one hot slot. Three prong outlet. So I fixed that, and wanted to see if the Neu. and Grd. were bonded in the dryer. Just looking at where the cord was landed on the dryer, It didn't look like it was. So I opened the whole back panel to make sure. I saw the Neu. and Grd. were butt spliced together inside, where you couldn't see it. So I figured all disconnect the Grd wire screwed to the frame, and cap it off.

Plug the dryer in, and check to see if there was any voltage on the frame. There was like 82V. Ok? I didn't understand why? So in a last ditched effort I screwed the Grd back to the frame like it was. Voltage was gone.

Any ideas? Thank you for your help.

 

[hurk27]

I tested the outlet and I got 240v. from the Neu. slot and one hot slot. Three prong outlet. So I fixed that, and wanted to see if the Neu. and Grd. were bonded in the dryer. Just looking at where the cord was landed on the dryer, It didn't look like it was. So I opened the whole back panel to make sure. I saw the Neu. and Grd. were butt spliced together inside, where you couldn't see it. So I figured all disconnect the Grd wire screwed to the frame, and cap it off.

Plug the dryer in, and check to see if there was any voltage on the frame. There was like 82V. Ok? I didn't understand why? So in a last ditched effort I screwed the Grd back to the frame like it was. Voltage was gone.

Any ideas? Thank you for your help.

Yes, when you floated that green wire you lost the 0 volt reference the neutral gave it, this is one of the reasons the code requires 4-wire dryer hook ups now, the 82 volts you saw was what we call ghost voltage, kind of a capacitive/inductive voltage, which would have gone away as soon as a load was placed across it, the problem is you should have had a EGC connected somewhere to the frame from the cord? does it have a 4-wire cord? is the EGC connected in the circuit feeding the dryer?

If not I would up sale a 4-wire circuit and cord to never allow this to happen again.

 

[ramsy]

1) Neutral should not be bonded to appliance frame, or it can seek other return paths, thru people touching the appliance.

2) If outlet has bootleg grounding, your bare/green wire is really a neutral bonded to frame, where it can shock people touching the frame

3) A high-impedance fault, energizing a gas line or other equipment can also shock people without passing enough current to trip a breaker.

 

[zappy]

Yes, when you floated that green wire you lost the 0 volt reference the neutral gave it, this is one of the reasons the code requires 4-wire dryer hook ups now, the 82 volts you saw was what we call ghost voltage, kind of a capacitive/inductive voltage, which would have gone away as soon as a load was placed across it, the problem is you should have had a EGC connected somewhere to the frame from the cord? does it have a 4-wire cord? is the EGC connected in the circuit feeding the dryer?

If not I would up sale a 4-wire circuit and cord to never allow this to happen again.

This was a three wire cord and plug. There was no ground connection. It was sitting on concrete though.

 

[iwire]

1) Neutral should not be bonded to appliance frame, or it can seek other return paths, thru people touching the appliance.

If it is an existing 3 wire installation the neutral is NEC required to be bonded to the fame.

 

[mcclary's electrical]

I tested the outlet and I got 240v. from the Neu. slot and one hot slot. Three prong outlet. So I fixed that, and wanted to see if the Neu. and Grd. were bonded in the dryer. Just looking at where the cord was landed on the dryer, It didn't look like it was. So I opened the whole back panel to make sure. I saw the Neu. and Grd. were butt spliced together inside, where you couldn't see it. So I figured all disconnect the Grd wire screwed to the frame, and cap it off.

Plug the dryer in, and check to see if there was any voltage on the frame. There was like 82V. Ok? I didn't understand why? So in a last ditched effort I screwed the Grd back to the frame like it was. Voltage was gone.

Any ideas? Thank you for your help.

Why are you going through the trouble to seperate neutral and ground on a 3 wire system? Now you've gone and made it more dangerous

 

[kwired]

I tested the outlet and I got 240v. from the Neu. slot and one hot slot. Three prong outlet. So I fixed that, and wanted to see if the Neu. and Grd. were bonded in the dryer. Just looking at where the cord was landed on the dryer, It didn't look like it was. So I opened the whole back panel to make sure. I saw the Neu. and Grd. were butt spliced together inside, where you couldn't see it. So I figured all disconnect the Grd wire screwed to the frame, and cap it off.

Plug the dryer in, and check to see if there was any voltage on the frame. There was like 82V. Ok? I didn't understand why? So in a last ditched effort I screwed the Grd back to the frame like it was. Voltage was gone.

Any ideas? Thank you for your help.

If you had 240 volt from the neutral to a hot on the receptacle not only would the frame be energized but the 120 volt controls and 120 volt motor would be toasted if they ran it that way.

If not hard to change to 4 wire circuit I would do that. Frame bonded to neutral and a concrete floor will always have some potential between them while in operation. A person standing barefoot on the floor will be vulnerable to that especially if the floor is wet.

 

[growler]

I tested the outlet and I got 240v. from the Neu. slot and one hot slot. Three prong outlet. So I fixed that, and wanted to see if the Neu. and Grd. were bonded in the dryer. Just looking at where the cord was landed on the dryer, It didn't look like it was. So I opened the whole back panel to make sure. I saw the Neu. and Grd. were butt spliced together inside.

Any ideas? Thank you for your help.

If you get 240V from phase to neutral that's not a neutral but the other phase and a good reason that someone was getting shocked. If you hook a hot wire to the frame of an ungrounded appliance that tends to be dangerous. So getting the neutral back to the neutral slot on the plug was a good idea. Always make sure that building power is correct.

Now the dryer. The neutral and the ground should not be butt spiced togather. They should be bonded to togather but the option remains to use this at a location with a 4 wire connection. They really should be bonded at the connection terminals. That way if it's ever sold or moved to a location with four wire it can be seen and seperated.

 

[zappy]

Why are you going through the trouble to seperate neutral and ground on a 3 wire system? Now you've gone and made it more dangerous

I had a brain fart.

 

[mcclary's electrical]

I had a brain fart.

It happens to everybody.:grin: I've had two this morning that really cost me alot of time. Had to go all the way back home to get my pipe bender.

 

[hurk27]

If you get 240V from phase to neutral that's not a neutral but the other phase

Nope it doesn't have to be the other phase or leg in this case, all it has to be is a bad neutral connection and the leg with the 120 volt motor and timer will be at 0 volts but the other leg to neutral will be at 240 volts, this is just like loosing a neutral to a service, but without the other leg having any neutral loads.

 

[LarryFine]

I saw the Neu. and Grd. were butt spliced together inside, where you couldn't see it. So I figured all disconnect the Grd wire screwed to the frame, and cap it off.

The right way to do that, and I've done it, is to separate the white/green splice you found (capping the white), make sure any nuetral-frame jumper is removed, keep the green wire bonded to the frame, and install a 4-wire cord as usual.

 

[kwired]

Nope it doesn't have to be the other phase or leg in this case, all it has to be is a bad neutral connection and the leg with the 120 volt motor and timer will be at 0 volts but the other leg to neutral will be at 240 volts, this is just like loosing a neutral to a service, but without the other leg having any neutral loads.

If dryer is not plugged in and you get 240 volts from line to neutral at the receptacle it is wrong polarity, or there could be neutral problems in feeder or service but you are more likely to not get a full 240 volts if other loads are connected to the feeder or service. If the dryer is plugged in it could be a bad neutral.

 

[growler]

Nope it doesn't have to be the other phase or leg in this case, all it has to be is a bad neutral connection and the leg with the 120 volt motor and timer will be at 0 volts but the other leg to neutral will be at 240 volts, this is just like loosing a neutral to a service, but without the other leg having any neutral loads.

If dryer is not plugged in and you get 240 volts from line to neutral at the receptacle it is wrong polarity, or there could be neutral problems in feeder or service .

Hurk you are right and this could happen with the dryer plugged in to provide a return path. Do you know of anyone that throuble shoots a dryer connection problem with the dryer plugged in? Zappy said that he was checking voltage at the slots and I assume that means the receptacle it's self. That's why I said you should make sure of building wiring first.

If I have a dryer problem I'm going to eliminate either the dryer or the building wiring as the cause and have only one possible problem to trouble shoot.

I guess both the dryer and the building wiring could be bad but if that happens I will deal with them as two seperate problems.

I still say from the description of the problem that he had one of the legs and the neutral reversed and this was putting 120V right to the frame of the machine and that's also why the breaker didn't trip (no return path ).

 

[hurk27]

Hurk you are right and this could happen with the dryer plugged in to provide a return path. Do you know of anyone that throuble shoots a dryer connection problem with the dryer plugged in? Zappy said that he was checking voltage at the slots and I assume that means the receptacle it's self. That's why I said you should make sure of building wiring first.

If I have a dryer problem I'm going to eliminate either the dryer or the building wiring as the cause and have only one possible problem to trouble shoot.

I guess both the dryer and the building wiring could be bad but if that happens I will deal with them as two seperate problems.

I still say from the description of the problem that he had one of the legs and the neutral reversed and this was putting 120V right to the frame of the machine and that's also why the breaker didn't trip (no return path ).

Yea I got a little assuming when I posted, as I was thinking this was a dryer that has been in use being a 3-wire circuit:grin: and if this was the case then the dryer would would have never worked if the hot and neutral were swapped, either it would have not turned on or the timer and motor would have burned up depending on which leg was used.