Shocked by Dishwasher and Stove

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Old 08-29-08, 01:10 PM
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Shocked by Dishwasher and Stove

Maybe I should cross post this in appliances (let me know). I installed a new dishwasher a few weeks ago and it has been working fine. Two nights ago, I was wiping down the counter when I happened to touch the metal rim on the stove and the anchoring tab on the dishwasher at the same time and got a hell of a shock.

I took out a current detector (the beeping kind) and it said there was electricity flowing in pretty much all parts of the dishwasher (stainless tub, anchoring tabs, stainless door). I also took a circuit detector (110/220 with lights) and touched it to various parts of the dishwasher and the rim of the stove, and a 110 current flowed between the tabs, tub, door and the rim of the stove.

I double checked where the wiring is connected to the dishwasher and all seems kosher. The current detector doesn't beep at the stove, so it would seem the problem is in the dishwasher. Could there be a problem with the wiring inside the dishwasher, as opposed to the connection? The dishwasher is a Bosch by the way.

Any help? Thanks, Jimbo
 
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Old 08-29-08, 01:58 PM
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Originally Posted by ssjimbo View Post
I happened to touch the metal rim on the stove and the anchoring tab on the dishwasher at the same time and got a hell of a shock.
Were either of the appliances turned on or otherwise activated at the time?

Do you happen to know if your stove is connected with a three-prong or four-prong plug?

I double checked where the wiring is connected to the dishwasher and all seems kosher.
Closely examine the clamp where the romex or cord enters the dishwasher. This symptom could result from a cable clamp or sharp metal edge which has cut into a wire. Is the bare ground wire properly connected to the metal box or frame of the dishwasher?

The current detector doesn't beep at the stove
Just for clarity, it's a voltage detector.

Could there be a problem with the wiring inside the dishwasher, as opposed to the connection? The dishwasher is a Bosch by the way.
It's possible, but that is a pretty rare case in my opinion. Most of the electrical components in a dishwasher are double-insulated from the user to prevent shocks.
 
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Old 08-29-08, 06:54 PM
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To find out which appliance is sending juice through it's chasis, test each appliance's chasis/metal skin, etc. to ground pin of outlet. Sounds like one of these appliances may have lost it's ground (especially if you feel more than a little tingle), and is using you to become it's bridge to the other appliance's ground circuit.

This happened to me once with an ungrounded refrigerator, when I touched the door and the stainless steel sink at the same time. Then I put my test meter between refrigerator and sink and got 120!
 
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Old 08-29-08, 07:04 PM
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This is a major safety hazard. Keep the dishwasher circuit breaker turned off until you solve this problem. What has so far just shocked you could kill you in other circumstances. Don't take any chances.
 
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Old 08-29-08, 08:27 PM
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Something is radically wrong here. No matter how screwed up you wired the dishwasher as long as you have a ground in place that is working it would blow the breaker. The same is true for the stove. The one difference is that older stoves used 3 wire connections and used the neutral as a ground. If this is the way yours is wired it might be a problem.

You need to determine which appliance is hot. You can CAREFULLY measure the case of the stove and then the dishwasher to a nearby water pipe. As i said if you connected the ground to the dishwasher and it is connected at the main panel then it should not be hot.

Is the dishwasher on its own circuit directly to the main panel? Can you identify the wire and breaker in the main panel?
 
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Old 08-29-08, 10:58 PM
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I have seen this happen on a three wire stove with a loose neutral. Basically the 120 electrics on the stove such as the clock were seeking a ground to replace the neutral. When the customer touched the stove while opening the properly grounded refrigerator it found it's path. A dish washer would offer a similar ground path.

Get an analog multimeter. Plug in an extension cord to a receptacle with a known good ground. Measure the voltage between the ground on the extension cord and the stove. If you get approximately 120 volts you have found the problem If not try measuring to the dish washer.

WARNING: This is a very dangerous situation. Be sure to NOT touch the stove or dish washer when the power is on for testing.
 
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Old 08-30-08, 12:26 AM
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As far what Ray is describing with exsting three wire range { stove } circuit the netural is used both current carry conductor and grounding more like two in one.

This is been around for many years sence WWII days it is fine for exsting wiring set up but a catch is that if the netural conductor go bad for some reason the range frame will be enerized when someone touching the frame to sink or fridge or other applainces and any thing is on 120 volts will try to find a netrual to get this item running like clock or light or even burner[s]

There is few possiblty where the netrual connection can go bad

Bad connection at the fuse/breaker box

Bad connection at the range receptale

Bad connection at the range junction box

A break or corroed wire{s}

That one of few items I mention above list but possiblty more but this list is a start and kinda pretty common location for bad connections

Let you know if some reason you have older SE cable don't always assumed it is a alum wire some of older SE cable are copper tinned wires the reason they were tinned so keep the rubber coating having a reaction to the copper.

The only way to make sure they are copper tinned is look at the side if you see copperish colour then you have copper wire but if all silverish colour then you have alum wire there.

Again please heed the warning about this.

This is very serious matter and that need to be taken care ASAP.

Turn off range fuse or breaker and other appliace fuse or breaker.
Do not turn it on unless you doing the testing as described above and once you isolated the curpit then you can do the trobleshooting

Merci,Marc
 
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Old 08-30-08, 01:06 AM
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You know this 3 wire, 4 wire, using the neutral as ground brings up a sore point with me. We quote code on here and grandfather many things BUT some things are just to dangerous to ignore. This stove issue is one of them. I know it costs money to replace stuff but we recall all kinds of products sometimes for trivial reasons then we ignore a potentially dangerous situation like this. Appliances and especially 240 appliances should have separate grounds, period.

We often argue (discuss) trivial code details on here but this is a no brainer. It is my opinion that we should tell people the truth. That this could potentially be a dangerous situation and while it is grandfathered, no code since the 90's (or maybe before) allows it. The code was changed for a reason.

I would think that electricians could be held responsible if they did not point out a known safety issue like this to a customer.

If this gentleman's Stove and dishwasher were wired with a proper ground we would not be having this discussion. and if he was not so lucky to be able clear himself from the shock he felt we would be reading about this in the obits!
 
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Old 08-30-08, 12:46 PM
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Thanks for the Advice

Wanted to let people know that I'm still alive. The wiring is indeed 3 wire. I know this from the breaker box, because this is a drop in model, 27 inches wide (which still leaves us scratching our heads. This is a particularly old stove, probably from the 70's or so.

I'm guessing the wiring is braided aluminum, the neutral/ground wire is for certain. The reason I don't know about the other two is that as the cable (cloth covered btw) come into the breaker box, they are connected to two copper conductors via taped nuts. My guess would be they did this when switching from fuses to breakers (the house was built in 1941). I have homeowneritus all over the house. I have been doing some minor rewiring as I upgrade certain items (bathroom remodel, new ceiling fan, etc). Many of the outlets in our home are groundless, using two wire armored cable.

But here's the thing, it is the dishwasher that gives 120 on my voltage tester (the 110/220 type), when I touch the metal on the body to a good ground. I don't have a multi-meter (I guess I should get one). So...should I pull the dishwasher out, or is likely that my problem is elsewhere on the circuit (I'm pretty positive that the wire into the dishwasher is connected correctly, but beyond that who knows what the previous homeowner did)? I'll keep checking the wiring on the circuit to see if I can find the problem before I pull out the dishwasher itself.

Lastly the dishwasher is not on its own circuit (yet). I wired it into the same circuit it had been on (yes I know that's not code), so I'll follow the wiring to the junction box (it's wired into a switch under the sink), and then from there into the breaker box. The circuit is 30 Amps though.

Thanks so much for the help and the concern. Jimbo
 
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Old 08-30-08, 01:28 PM
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Quick note. The dishwasher appears to be connected to an ungrounded circuit. I'm going to fix that ASAP. Even though the stove is on a 3 wire circuit, it doesn't appear to be the problem.
 
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Old 08-30-08, 06:29 PM
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Success!! The dishwasher is now grounded, and no longer lights a voltage detector when connected to the stove or ground. The previous wiring was amazing, and undoing it will be a chore (I left it terminated in a box), but the dishwasher is no longer on an ungrounded circuit.

I've got a couple more questions, but I'll start a new topic. Thanks so much for the great help everyone has been. Have a great holiday weekend.
 
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