Electrified countertop


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Old 09-09-14, 09:44 AM
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Electrified countertop

Kitchen, 1.5 years since remodel. All new electric, appliances, stainless steel counter. Ontario.

While out of town, my wife called to say she was getting shocks from the dishwasher panel. Panel is on top of the open door.

Electrician couldn't reproduce problem, repairman registered minor voltage between dishwasher case and counter. Breaker to dishwasher was turned off until new board for dishwasher arrived and was installed.

No new shocks from dishwasher. But this morning wife reported shocks while holding body (steel) of coffee maker and touching steel countertop. I could reproduce. Also found shock touching counter and range hood, electric (induction) stove to range hood. Registered voltage with multimeter as well.

Troubleshooting, I found that opening the breaker to the dishwasher did nothing to reduce the voltage readings, but opening the stove breaker did. Pulled out stove and discovered that the plug was about 1/2 inch out of the outlet. Pushed it in fully, reset the breaker, and no more shocks/ voltage from the stove or coffee maker. The stove is a tight fit to the counter tops.

I am reasoning that the ground was not in contact on the stove with the plug partly out, and somehow the counter was registering a low voltage as a result. Touching the counter and other appliances which are grounded gave a shock as we were connecting the stove to ground.

Two questions: Is my guess reasonable? Is there something wrong with the stove?

Thanks!
 
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Old 09-09-14, 10:01 AM
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Is there something wrong with the stove?
Maybe. Am I correct in assuming you have a 3 prong receptacle and 3-wire range cord?
 
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Old 09-09-14, 10:16 AM
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Yes, I believe so. Will confirm.
 
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Old 09-09-14, 12:52 PM
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Actually, 4 prongs on the cord.
 
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Old 09-09-14, 05:23 PM
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It sounds to me as if you have an intermittent fault within your range, but it isn't enough to trip a 40 or 50 amp breaker. It may be intermittent as the thermostat for the particular bad element cycles.
 
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Old 09-09-14, 05:58 PM
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Two questions: Is my guess reasonable? Is there something wrong with the stove?
Here's my guess...... you only have a two wire cable with ground coming from the panel to the four prong receptacle. In servicing appliances I've seen it many times.

Is there anything wrong with the stove..... not likely. As elements age their tendency to leak to ground increases. That is another reason for the change to a four wire supply cable, four wire receptacle and a four wire power cord.

I would have the receptacle checked for the four wires that should be there. If it's hard to pull the range out maybe you can see the cable on its way to the panel or at the panel.
 
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Old 09-10-14, 08:11 AM
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Thanks for the suggestions. I would have expected the electricians to have wired this properly, given the recent installation, but I'll have to double check.

Thanks again.
 
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Old 09-10-14, 08:16 AM
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Also the stove installer may never have disconnected the ground from the neutral at the stove when the four wire cord was installed.
 
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Old 09-12-14, 10:32 AM
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I've never seen this done before - so wait to see what the pros have to say, but from what I understand about grounding/bonding, it's probably a good idea...

Code requires you to bond (ground) metallic systems in your house. This includes plumbing pipes, cable TV, telephone, ductwork, etc. I think your stainless steel countertop should be bonded to ground as well. It would require drilling a hole in an inconspicuous location, mounting a bolt with a wire connected to a nearby junction box. I don't know how best to actually install it, but it seems like it would be a good long-term safety addition.

Thoughts?

These shocks your wife has been experiencing have been a nuisance, but what if next time it is a full 40A shock?
 
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Old 09-12-14, 05:26 PM
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The countertop is grounded...... probably thru the sink and faucets. It's the range that wasn't grounded.

If the countertop wasn't grounded then touching it and the range would have caused no shock.
 
 

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