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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?

skybreaker
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  • 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 00:26

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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.

bcworkz
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  • Thank you for your great reply. you are an electric Sherlock! – skybreaker Jan 19 '14 at 03:45
  • 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. https://lh3.googleusercontent.com/-E3h99PbZ23c/UtpI6Z-s0gI/AAAAAAAJMoY/Rr80cM_w2mk/s0/IMG_20140118_195049.jpg Could this be causing the wires to cross in the plug somehow? – skybreaker Jan 19 '14 at 03:46
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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 01:02
  • 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: http://images02.olx.co.za/ui/19/10/38/1359020397_475990238_1-AU-EU-US-to-UK-AC-Power-Plug-Travel-Adapter-Converter-Travel-Adaptor-Parow.jpg 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
  • Hmm, I'd have thought if they flipped wires, using it again would flip it back. I'd imagined you used adapters of different makes for a one way flip. Not good either way. And now that you mention it, there could be something wrong with the building grounding and nothing wrong with your washer. I'm not sure those little power point testers would detect this sort of problem or not. It may take a proper electrician to inspect and diagnose what else is wrong besides the polarity flip. Something else is wrong because a polarity flip alone would not cause a shock. – bcworkz Jan 22 '14 at 06:21
  • Well, the UK and AU plugs form a "T" shape. But in the UK it's upside down. They both have neutral on the right side. But the cheap adapters keep the "T" facing up, so the UK is upside down. On my more expensive adapter the AU and UK are both facing the right way. So, you would think that the neutral would stay on the right... but maybe one of the adapters is attempting to correct the fact that the "T" is facing the wrong way... by flipping the wires' positions... but then the UK to AU adapter is not... – skybreaker Jan 22 '14 at 11:55
  • Either way, if polarity is flipped or grounding is dysfunctional - this would require that either a neutral or active wire inside the washing machine was inappropriately touching the chassis, right? Is that correct? – skybreaker Jan 22 '14 at 11:56
  • One condition for this to happen is the polarity must be flipped, otherwise you would have been shocked long before this. The other condition is either one, you washer has faulty wiring, or two, grounding is faulty such that active current from the polarity flip somehow back fed the normal washer chassis ground. You could have then been shocked from the outer cabinet as well. It may have just been dumb luck that you did not. The washer could be fine. Honestly, faulty washer wiring seems more likely than faulty building grounding. (continued...) – bcworkz Jan 24 '14 at 03:34
  • But I've not seen the condition of either, so that could seriously skew an estimation of which is more likely the cause. It's also possible both could be faulty, though only one or the other would be the actual cause. – bcworkz Jan 24 '14 at 03:37
  • Hi. It's been 1 year since your last comments, but I wanted to provide an update and ask additional questions. Per your advice, I purchased and trained up on how to use a multimeter in order to diagnose this issue.

    My results: From ground on plug to drum is infinite to 120,000 ohms resistance (changes when it moves). To other parts of the metal chassis it shows 83 ohms resistance. The live and neutral prongs on the plug show infinite resistance to each other.

    All other readings are infinite/blank, including voltage and current readings from drum and chassis while they are energized. cont...

     – skybreaker Jan 13 '15 at 17:37
  • I don't understand how I can get shocks from the drum and chassis and they can set my proximity voltage alarm off, but no readings come through the multimeter. Is it because I can only rest the probes on the metal drum and the resistance is too high in my multimeter and the current is happier to flow through the chassis? – skybreaker Jan 13 '15 at 17:37
  • I also discovered a disturbing fact: the polarity does not even need to be flipped for the chassis and drum to become energized - I tested inserting a plug adapter with no ground connection between the washing machine plug and the power outlet. (so it just has live and neutral connections). The same effect occurred: the drum became energized and putting my proximity voltage detector within 40cm of the unit resulted in it beeping (it usually needs to be within 1cm to detect anything.) – skybreaker Jan 13 '15 at 17:38
  • My question is: does this mean that the washing machine drum was always energized, and the only thing saving me from being shocked was that the ground wire was safely attracting the current away from me when I touched the machine? Does this mean that the only possibility is that somewhere inside the machine a live wire is touching the metal exterior of the machine?

    Thanks again for your help.

     – skybreaker Jan 13 '15 at 17:39