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I bought this plug-in power monitor four years ago. I have used it all over my house without issue. I should note that it is designed for UK plugs (I'm in Australia), so I've had to use some plug adapters. Because the UK plug adapters are "upside down" compared to australian plugs, could this be switching the polarities?

Yesterday I put it inline with my washing machine plug to test its usage. After I removed the clean clothes, I touched the metal case of the drum inside and received a decent strength electric shock.

I have been shocked before and I would say that this felt like about 50% of the strength of getting shocked directly from the power-point. It was an intense buzzing in my hand which left it sore for 30 mins after.

I used my proximity voltage detector which started beeping as soon as it came near the washing machine drum.

Having removed the power monitor, I've checked all over the washing machine with the voltage detector and it has not detected any power leakage in the drum or case.

4 years ago my washing machine was attached to a power point that burned and melted. I never found out the cause. Here is a picture of the washing machine plug. Could this be causing the wires to cross in the plug somehow?

Can I safely use my washing machine?

Since there is no leakage detected when the power monitor is removed, can I safely assume that it is the culprit?

Is there any way to test if they Neutral wire is touching the drum when the machine is just plugged straight into the wall and my voltage detector doesn't detect anything?

  • You mention using adapters. By chance are you using an adapter that excludes the grounding conductor? – Tester101 Jan 18 '14 at 15:55
  • No. But it does appear to flip the polarity. – skybreaker Jan 20 '14 at 12:17
  • Electric dryers may have the grounded (neutral) conductor bonded to the chassis of the dryer. If your adapter is flipping the polarity, the dryer chassis may be bonded to the ungrounded (hot) conductor. Basically the adapter is causing the chassis of the dryer to be electrified. – Tester101 Jan 20 '14 at 12:30
  • Thanks for that. I confirmed with the manufacturer that they do not bond the neutral wire to chassis or drum. – skybreaker Jan 21 '14 at 0:26
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There needs to be multiple compounding faults for you to get a jolt like that from the tub. The tub should be grounded to earth, but to give you a jolt, it would need to be instead bonded to one of the mains lines. Since your detector is no longer complaining, it must be bonded to the neutral line. While a bad situation, in normal use there are likely no adverse effects from this.

The other thing that needs to happen is a polarity reversal from either the power monitor or one of the plug adapters. For example, if you accidentally got an UK to Argentine adapter, it would appear outwardly to be for Oz, but in fact the neutral and active pins would be reversed. This too is bad, but also usually no adverse effects are apparent.

Now you have active mains power running down the neutral washer wiring, which inappropriately includes the tub. If the tub were properly grounded and active power somehow came in contact with it, the breaker would trip or the fuse would blow. Having been instead bonded to neutral, and now hot due to polarity reversal, two somewhat innocuous errors combine to become a potentially deadly combination!

First identify which device is reversing polarity. Looking at a wall outlet, with the ground pin on the bottom, both UK and Oz outlets have neutral on the right. Anything that switches sides should be destroyed. Not just thrown out, destroyed, as in render unusable.

The washer should be inspected and the connection to neutral identified and removed. It may be simply a wire with worn insulation that needs to be replaced, or something more intentional. It's impossible to say without inspection. The situation has not changed from before. While the tub bonded to neutral cannot ever be called "safe", as long as polarity is observed, nothing really bad should happen. You can still get shocked from this because the neutral and true ground are likely at different potentials, but nothing like the full 220v jolt you got.

  • Thank you for your great reply. you are an electric Sherlock! – skybreaker Jan 19 '14 at 3:45
  • I had some questions: Is there any way to test if they Neutral wire is touching the drum when the machine is just plugged straight into the wall and my voltage detector doesn't detect anything? 4 years ago my washing machine was attached to a power point that burned and melted. I never found out the cause. Here is a picture of the washing machine plug. lh3.googleusercontent.com/-E3h99PbZ23c/UtpI6Z-s0gI/AAAAAAAJMoY/… Could this be causing the wires to cross in the plug somehow? – skybreaker Jan 19 '14 at 3:46
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    The plug looks OK, no sign of melting, the burnt marks appear to have come from the power point. There's no way polarity could have been reversed in that component. You need a multimeter to test resistance between the neutral pin on the plug (while unplugged!) and the tub itself. The neutral side is the one with burn marks, but measure all pins just to collect data. The slanted pins should be infinite resistance and the vertical pin should be low resistance. If you don't have a multimeter, consider getting one, they are handy and basic ones are not very expensive. – bcworkz Jan 20 '14 at 1:02
  • I found that the power monitor is not the culprit for the polarity switch. All I need to switch the polarity is a AU to UK adapter then a UK to AU adapter plugged together. Because the UK plugs are "upside down" with the two pins on the bottom, the way the cheap adapters are designed it's actually flipping the wires. See: images02.olx.co.za/ui/19/10/38/… If it wasn't for your excellent response I wouldn't have been able to convince the manufacturer to send someone to investigate. – skybreaker Jan 20 '14 at 12:14
  • Another question: would any of this suggest that the grounding cable in my building isn't functioning correctly? – skybreaker Jan 20 '14 at 12:18

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