220v dryer outlet wired wrong, wtf?!

[Leros]

I moved into a house a few weeks ago and my new washer/dryer showed up a few days ago. The installers wired up a cable and plugged it in. The outlet sparked and started smoking so they removed the cable.

I assume something is wrong with the dryer because I had seen the previous resident's dryer running when I checked out the house. So I called LG and they sent a technician out to look at the dryer.

The LG guy probed the dryer outlet with a multimeter and told me I had bad voltages on the outlet. He wasn't authorized to go past the outlet, so I called an electrician.

The electrician came out this morning. After looking at the outlet and the breaker, he determined the whole thing was just wired totally wrong. The wrong voltages were going to the wrong pins on the outlet. Not only that, but the wiring was used incorrectly (the exposed ground wire was live!!!!). They had it hooked up wrong at the breaker.

He wired everything up right and, miraculously, my dryer still works. I feel like I'm lucky this place didn't burn down.

The WTF thing is that the previous resident's dryer worked. Which leads me to believe that they wired their dryer cable wrong and fixed it by messing with the 220v dryer wiring instead.

Since this thread has been revived, I moved it from OT.
admin allisolm

 

[cerebusPu]

goodness. this exact same thing happened to me except 1) my old dryer worked for a few months and started getting not as hot 2) my new dryer blew up immediately after turning it on 3) i determined myself that the outlet was wired wrong with a multimeter

i have no idea how the old dryer continued to work with the ground pin being hot.

 

[mmntech]

It's a wonder they didn't electrocute themselves with the ground pin being hot. The entire metal case would be electrified!

 

[Modelworks]

This is going to be happening to a lot of people unfortunately.
There was a code change on dryers and the wiring. Previously they used 3 wires. Two hot wires and neutral+ground were combined with a strap that attaches to the screw on the back of the dryer near where the cord attached.

Now the code is changed so that you have 4 wires. Two hot wires , neutral, ground, and that strap has to be removed from the dryer or you get neutral and ground being connected together, which in some homes actually carries voltage due to poor wiring.

 

[Leros]

This is going to be happening to a lot of people unfortunately.
There was a code change on dryers and the wiring. Previously they used 3 wires. Two hot wires and neutral+ground were combined with a strap that attaches to the screw on the back of the dryer near where the cord attached.

Now the code is changed so that you have 4 wires. Two hot wires , neutral, ground, and that strap has to be removed from the dryer or you get neutral and ground being connected together, which in some homes actually carries voltage due to poor wiring.

Yeah, I have a 4 pin outlet but only a 3 wire cord in the wall.

The electrician just connected neutral and ground together and called it a day.

 

[disappoint]

All I know is , the black wire is black because it stands for death.

The red one just means bloody death.

 

[NutBucket]

Gas dryer would have eliminated the problem

 

[SphinxnihpS]

This is going to be happening to a lot of people unfortunately.
There was a code change on dryers and the wiring. Previously they used 3 wires. Two hot wires and neutral+ground were combined with a strap that attaches to the screw on the back of the dryer near where the cord attached.

Now the code is changed so that you have 4 wires. Two hot wires , neutral, ground, and that strap has to be removed from the dryer or you get neutral and ground being connected together, which in some homes actually carries voltage due to poor wiring.

FTFY

 

[pcgeek11]

This is going to be happening to a lot of people unfortunately.
There was a code change on dryers and the wiring. Previously they used 3 wires. Two hot wires and neutral+ground were combined with a strap that attaches to the screw on the back of the dryer near where the cord attached.

Now the code is changed so that you have 4 wires. Two hot wires , neutral, ground, and that strap has to be removed from the dryer or you get neutral and ground being connected together, which in some homes actually carries voltage due to poor wiring.

I have seen where not removing the ground strap will cause the neutral wire to be very hot! On more than just 220 dryers. That is where the issue is most of the time.

 

[BoomerD]

This is going to be happening to a lot of people unfortunately.
There was a code change on dryers and the wiring. Previously they used 3 wires. Two hot wires and neutral+ground were combined with a strap that attaches to the screw on the back of the dryer near where the cord attached.

Now the code is changed so that you have 4 wires. Two hot wires , neutral, ground, and that strap has to be removed from the dryer or you get neutral and ground being connected together, which in some homes actually carries voltage due to poor wiring.

We bought a new dryer 3 years ago. It came with a 4-wire cord...my house has the older 3-wire plug. I went to Home Depot to buy a new pigtail...the guy in electrical tried to convince me that I had to have the plug re-wired...until I showed him the manual that explained how to connect a 3-wire pigtail for the dryer. "Huh. I learned something new today. I've been telling everyone that they have to have a new outlet installed."

http://www.ezdiyelectricity.com/?p=445

 

[ShawnD1]

I have seen where not removing the ground strap will cause the neutral wire to be very hot! On more than just 220 dryers. That is where the issue is most of the time.

The only thing I can think of that would cause this is if the wiring inside the dryer tied the neutral and ground together. If neutral and ground are also tied together at the receptacle, this creates a closed loop that would allow "circulating current" to happen. That's an effect seen when two or more wires are tied together at multiple points but the wires are different lengths or different sizes. This is why the electrical code states that wires connected in parallel must be exactly the same size and length of wire. This is also why devices are not allowed to have multiple ground points.

You can easily test if your dryer's wiring internally connects the neutral and ground together. Unplug the dryer then use a multimeter to check resistance between the neutral and ground connections of the dryer plug. 0 resistance = common. can't measure resistance = isolated.

The dryer should still work even when it's not grounded at all. The grounding has nothing to do with the actual operation of the device. It's only there to protect you against shocks. Leaving the device ungrounded just means you could potentially get a 120V shock if you touched the case of the ungrounded dryer then touched something that is grounded like a refrigerator or a water pipe. Actually I have a fun story about that. In my parents house, you will feel a very mild tingling in your fingers if you touch the door of the refrigerator and touch the oven at the same time. Both devices are grounded, but bonding the two together allows circulating current, and that circulating current passes through you.

General info:
Red and black are your live wires and carry the bulk of the current.
White carries the unbalanced load between red and black (10A on black and 5A on red would mean 5A go from black to white).
The ground wire has absolutely nothing to do with the load. The ground wire connects to the case of the electrical device and should never have current passing through it.

The electrician came out this morning. After looking at the outlet and the breaker, he determined the whole thing was just wired totally wrong. The wrong voltages were going to the wrong pins on the outlet. Not only that, but the wiring was used incorrectly (the exposed ground wire was live!!!!). They had it hooked up wrong at the breaker.

So.... the ground pin was actually hot, then the neutral was probably still neutral, and the two might be tied together inside the dryer itself. Power would go from the wall's ground wire (actually wired as hot instead of ground) --> into the dryer's ground wire --> internally connected to the neutral wire --> goes back to the wall's neutral wire. A dead short and it runs right through the dryer.
Worst case, you would probably just need to replace the neutral and ground wires leading up to the point where they connect. The brains of the dryer were probably not touched. This likely all happened at the case of the dryer, away from the motor, away from the heater, away from the electronics.

 

[olds]

220 takes an ounce of skill to wire correctly.
A couple of years ago I sold a guy a 220v air compressor. A couple of days later he said that it wasn't running right. I was going to refund him but I took my dmm just in case. He had wired an outlet for the compressor incorrectly. I rewired it and the compressor was fine. He said thanks, I figure I should have charged him for a service call.

 

[olds]

It's a wonder they didn't electrocute themselves with the ground pin being hot. The entire metal case would be electrified!

I can see it now, leaning on the dryer and reach over to turn the hose bib off....

 

[ShawnD1]

I can see it now, leaning on the dryer and reach over to turn the hose bib off....

OP said the thing smoked as soon as it was plugged in, so presumably they would only lean over the dryer when it was not plugged in

 

[consolibyte]

We bought a new dryer 3 years ago. It came with a 4-wire cord...my house has the older 3-wire plug. I went to Home Depot to buy a new pigtail...the guy in electrical tried to convince me that I had to have the plug re-wired...until I showed him the manual that explained how to connect a 3-wire pigtail for the dryer. "Huh. I learned something new today. I've been telling everyone that they have to have a new outlet installed."

http://www.ezdiyelectricity.com/?p=445

The problem with this solution is that it can *void the warranty* on the dryer.

Our new LG dryer mandates that we use a specific 4-wire plug (I forget if it's the one with the L shaped prong or the one without). If you don't use that exact plug and configuration, your warranty is void. If you swap the pigtail on the dryer, your warranty is void.

 

[Modelworks]

A little history on the whole 3 vs 4 wire plugs . If you go back about 20 years dryers contained parts that were a mix of 240VAC and 120VAC items. Things like the heating element would be 240VAC while the timer would run from 120VAC. To get the 120VAC for the timer they connected the timer across one of the hot wires and the white neutral wire. This wasn't a problem until grounding for safety became part of the law. Now the neutral wire was also used for grounding the appliance because most homes didn't have a dedicated ground.

Using the neutral as ground worked fine unless the neutral wire worked its way loose in the outlet or the homes wiring, if that happened you would now have the 120VAC items like the timer looking for a return path, which now is also the metal frame of the appliance. A temporary solution was brought about that made it against the code to use 120VAC items within some appliances due to the shock hazard they created but not everyone, in fact not many, followed that code.

Enter the 4 wire system. The 4 wire system added a dedicated ground wire that would attach to the frame of the appliance , while the neutral would now become the dedicated return wire for anything that needed 120VAC inside the appliance.

If my home had a 3 wire system I would consider getting it rewired for 4 wire due to the shock hazards on 3 wire systems. At the very least consider double checking the tightness of the wiring inside the outlet and the connections on the dryer. If that neutral loosens then shocks can result.

This is just the industry playing catch up. 120VAC outlets used to be the same way without ground and using the neutral for a ground. That is why you still have outlets where one slot is wider than the other. That is to accommodate older items that still use the neutral for grounding and keeps the user from plugging in an item and connecting the hot to the items frame.

 

[ShawnD1]

Using the neutral as ground worked fine unless the neutral wire worked its way loose in the outlet or the homes wiring, if that happened you would now have the 120VAC items like the timer looking for a return path, which now is also the metal frame of the appliance.

And this is bad because.... why? The impedance from the dryer frame to the receptacle is ~0 ohms. Resistance from you to ground is 50,000 ohms. You will not be shocked.

Fun story about that. In one of our electricity labs, the instructor demonstrated that it is safe to touch current carrying conductors as long as the path presented by your body is shorted out by a metal conductor. The test is simple. The load for the circuit is a 1000W cone heater and it's connected through a simple switch with exposed terminals. With the switch closed and the cone heater running, you can put your index and middle fingers on each side of the switch and nothing happens. As soon as you open the switch, you get shocked.
The frame of the dryer is not a switch. It never opens. It's always shorted out. There could be 30A running through the dryer frame and you can still safely lick the frame without getting shocked.



A temporary solution was brought about that made it against the code to use 120VAC items within some appliances due to the shock hazard they created but not everyone, in fact not many, followed that code.

Enter the 4 wire system. The 4 wire system added a dedicated ground wire that would attach to the frame of the appliance , while the neutral would now become the dedicated return wire for anything that needed 120VAC inside the appliance.

If my home had a 3 wire system I would consider getting it rewired for 4 wire due to the shock hazards on 3 wire systems. At the very least consider double checking the tightness of the wiring inside the outlet and the connections on the dryer. If that neutral loosens then shocks can result.

This is just the industry playing catch up. 120VAC outlets used to be the same way without ground and using the neutral for a ground. That is why you still have outlets where one slot is wider than the other. That is to accommodate older items that still use the neutral for grounding and keeps the user from plugging in an item and connecting the hot to the items frame.[/QUOTE]

 

[Red Squirrel]

It's scary some people will do electrical without actually knowing what they're doing. A dryer plug is not really that hard to wire.

 

[ShawnD1]

They don't know that they don't know what they are doing. Some of the screwups are little things you don't think about. Aluminum and copper conductors use different receptacles; the receptacles used in a copper wired house should not be used in an aluminum wired house. You can put a switch on the black or the white wire and both will work, but putting a switch on the white wire is actually illegal and it's more dangerous. When adding duplex receptacles to a kitchen, a lot of people don't know that it's conventional to use a 3-wire Edison scheme then connect it to a double pole breaker. That means the top plug is on the red phase, the bottom plug is on the black phase, but overloading either phase will turn off both phases.
For a lot of this stuff, there's no way you could know that unless someone told you or you read the code book. I had to pay $130 for the code book so I'm guessing most people don't have one.

A dryer plug is simple, but I mean in general a lot of it is stuff you can't figure out just by looking at it.

 

[Modelworks]

And this is bad because.... why? The impedance from the dryer frame to the receptacle is ~0 ohms. Resistance from you to ground is 50,000 ohms. You will not be shocked.

It is bad because it relies on the neutral remaining in connection with the homes wiring. Should the neutral lose the connection then the frame becomes live.

 

[Modelworks]

It's scary some people will do electrical without actually knowing what they're doing. A dryer plug is not really that hard to wire.

Most of the time it is because of lack of experience. People don't have to re-wire outlets often so they never bother with learning about it, then when they need to know they look for the easiest method to learn, usually a quick glance at a book or website .

I learned from the time I was 15 when we needed a new air conditioner and the one we got was 240VAC and we didn't have an outlet for it. I was the only one in the home at the time even halfway willing to learn how and my dad was going to return the unit and just have us use fans if he had to pay to have an outlet installed. I was lucky to have a family friend that was a ham radio guy and he told me what to buy and how to do it. Even then it didn't work and he had to come to find out why. I had tightened the cable clamp too tight and broke one of the wires ,

Then later my brother started setting up mobile home parks and was paying thousands on each one to get the electrical set up so he asked me if I could do it, I assumed I could because I was working as an EE. I got the books, followed the courses and can now do wiring in NC . It really isn't a hard thing to learn if you have basic math skills. The hardest part is figuring out loads for an entire home and what size service is needed and wire sizes.

 

[ShawnD1]

It is bad because it relies on the neutral remaining in connection with the homes wiring. Should the neutral lose the connection then the frame becomes live.

If the neutral disconnects, the 120V circuits suddenly turn into 240V circuits. You would know something is wrong when the entire house smells like burning plastic and the smoke is coming from the dryer :biggrin:

I guess I see your point though.

 

[Modelworks]

If the neutral disconnects, the 120V circuits suddenly turn into 240V circuits. You would know something is wrong when the entire house smells like burning plastic and the smoke is coming from the dryer :biggrin:

I guess I see your point though.

If the neutral disconnects you have an open 120VAC circuit. From leg to leg on the black and red are 240VAC . A timer motor would be wired from one leg of the 240VAC and connected to the neutral wire, when you remove the neutral you have one side of the 240VAC or 120VAC left with no other connection except the frame of the dryer. The user will not notice anything wrong until they contact the metal frame. Most laundry areas are also wet and contain soaps and oils that increase conductivity. So the user stands in a wet area and contacts the frame making a good 120VAC path through the user

 

[ShawnD1]

If the neutral disconnects you have an open 120VAC circuit. From leg to leg on the black and red are 240VAC . A timer motor would be wired from one leg of the 240VAC and connected to the neutral wire, when you remove the neutral you have one side of the 240VAC or 120VAC left with no other connection except the frame of the dryer.

Depends where the connection is broken. If you break the connection at the receptacle or in the dryer's cable leading to the receptacle, phase to neutral connections turn into phase to phase connections and it usually changes the voltage.

In the above picture, Rx is normally 120V. When the neutral is broken, it turns into (240V * Rx) / (Rx + R2).
Now ask yourself what kind of loads normally go on the phase to phase 240V circuit? That's probably the heating element, a low resistance load. Rx might be some electronics and computer stuff, so we'll say that 100 ohms. Heating element R2 pulls a lot more current, so we'll say that's 10 ohms. With the neutral broken, the 120V going to the electronics suddenly turns into (240 * 100) / (100 + 10) = 218V

It would make a lot of smoke :awe:

 

[Modelworks]

Depends where the connection is broken. If you break the connection at the receptacle or in the dryer's cable leading to the receptacle, phase to neutral connections turn into phase to phase connections and it usually changes the voltage.

It is going to depend on the dryer model too. Some dryers have lights inside that switch on when you open the door. A dryer like that with no neutral and turned off would be fine until someone grabbed and opened the door, then the switch would close the circuit across the bulb and being no neutral but the person, they would become the ground .

A schematic with lamp assembly. Notice also in this one that the element is 240VAC but the motor is 120VAC, making it even more hazardous.
http://www.managemylife.com/images/5199/original/174.jpg?1297801659