Getting a shock from kitchen appliances?


Old 02-15-20, 04:43 AM
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Getting a shock from kitchen appliances?

I have an old kitchen (1950's) and appliances. Range top, Espresso machine(SS), built in oven, hood, a metal SS sink. So I noticed by no subtle means that a current is passing thru these appliances when we touch and make contact between two close appliances. I have put a meter between a few of them and I get all kinds of low voltages.Where do I begin in trouble shooting to find the problem. The only thing I can add is maybe ten years ago I removed the top element in the built in wall oven. I thought I capped off the loose wire ends. Its a bit of a pain to pull out the oven, but if I need to start there I will.
PS I also see the outlets are testing open ground
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Old 02-15-20, 05:19 AM
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Start by checking all the ground connections inside the appliances and the electrical system boxes.
Old 02-15-20, 09:11 AM
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I also see the outlets are testing open ground
In a 1950s kitchen I would expect to see 2-wire NM cable with no grounding conductor so open ground would be correct because there wouldn't be a ground wire. Use your meter and measure the voltage between the frame of each appliance to the stainless steel sink and see what you get.
Old 02-16-20, 03:01 PM
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I would also check if your plumbing system is grounded/bonded. Does it have a wire connected to the metal piping from the main panel. Nowadays it needs to be near where it comes into the house - but yours is likely at the closest point between the piping and electrical box.

If there's an accidental short between the plumbing pipes and electrical system - this will ensure that the breaker trips quickly.
Old 02-16-20, 06:41 PM
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At some point in the troubleshooting you will need to disconnect each appliance from power. At least for the range, you can unplug it although the plug could be hard to reach.

Measure resistance from the appliance frame or exposed metal to each of the "hot" supply wires coming from it (or the plug prongs one at a time. You should get nearly infinite resistance (or no continuity) from either hot prong or wire to the frame. Otherwise there is a defect in the appliance.

Flip off the breaker for the appliance circuit (each appliance circuit in turn) With the power off measure resistance from each hot conductor to the metal sink. You should get nearly infinite resistance for these tests also..
Old 02-17-20, 04:41 AM
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Has any plastic piping been added to house? if so if may have broken the ground there.
Old 02-17-20, 05:57 AM
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A grounding electrode conductor (fat wire from panel) to approved water pipe connection can double as the needed bonding jumper from cold water plumbing to the panel neutral (house ground reference; root of the grounding electrode system). To complete this connection another bonding jumper is needed across the meter inlet and outlet..

If there is no pipe grounding electrode, i.e. the main water pipe is plastic exiting the house, then the aforementioned long fat wire is no longer a GEC but can be a bonding jumper. Then, if the former were not present, a bonding jumper (same sized wire) elsewhere, for example from the cold water plumbing at a point closest to the main panel, to the panel, is acceptable.

Grounding electrodes including ground rods are not good and sufficient to prevent electric shock from energized appliance exteriors and other exposed metal that gets energized. Running a ground wire (equipment grounding conductor), even haphazardly, attached to the metal exterior and also to a good ground in the panel with the breaker for the appliance circuit (or to a GEC) will greatly reduce the hazard. (Such a haphazard EGC is often used for reducing hum in stereo systems and other electronics or improving reception of ham radio.)

It is still necessary to troubleshoot and fix the problem causing the electric shock.
The EGC will do one of two things:
1. Reduce the potential difference (voltage) between the far end (the appliance exterior or whatever) and the panel connection (house ground) which will greatly reduce the chance of accidental electrocution.
2. Draw enough power to trip the breaker.
The EGC in performing #1 well can still result in a small continual or continuous current flow that makes a noticeable increase in your electric bill.

Last edited by AllanJ; 02-17-20 at 06:24 AM.
Old 02-18-20, 01:50 PM
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I have an old kitchen (1950's) and appliances.
If it is 1950s wiring, you probably had un-polarized plugs, and one of the polarized plugs has"hot" and "return" swapped.
Try a simple "plug in circuit tester"

with an adapter.

which should tell you what is going on.

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