Can washing machine on/off switch cause RCD to trip?

[NowWhyisThat?]

Hello all. Wonder if anyone can answer a quick query regarding an intermittent RCD trip out issue I’m having which occurs only when I press the on/off switch on my Samsung washing machine.
The trip out only occurs when the washing machine is switched on. After then re-setting the RCD the machine then behaves completely normally and there are no interruptions to the wash cycle.
I’ve had my electrics checked out by a professional and they have been given a clean bill of health.
I then had a washing machine engineer out to look at it it and after I described what was happening he confidently stated that the heating element needed changing. So he changed the heating element and guess what? The trip out issue continues to persist on an intermittent basis.
Don't want to now throw good money after bad unless I know what the problem actually is.
Could it be the on/off switch that is responsible for these intermittent trip outs? Or something in the pcb board? I’m pretty certain it isn’t the motor, as the machine is only 6 years old and a direct drive model. Would like to know if the on/off switch could be the culprit. Thank you.

 

[JohnW2]

Hello all. Wonder if anyone can answer a quick query regarding an intermittent RCD trip out issue I’m having which occurs only when I press the on/off switch on my Samsung washing machine. .... The trip out only occurs when the washing machine is switched on. After then re-setting the RCD the machine then behaves completely normally and there are no interruptions to the wash cycle.

No-one seems to have a particularly convincing explanation about how/why it happens, it seems that it sometimes does - and sometimes even more mysteriously by happening only when one switches something 'off'.

It's not impossible that a faulty RCD could be to blame but, although a finger often gets pointed in that direction, it's a pretty rare cause of such issues.

Is this happening every time (or most times) the machine is switched on? If so, then it would probably be worth getting an electrician to check out both the RCD and the WM.

Kind Regards, John

 

[JohnW2]

One further thought. If the WM has 'filter capacitors' on its mains input and if the switch you are operating is upstream of those capacitors, then it's possible that 'initial leakage' through one of those capacitors might be tripping the RCD. If that were the case, it could either be due to a faulty ageing capacitor (causing it to have excessive leakage) or to an unduly 'trigger happy' RCD (tripping with a low leakage current which shouldn't cause it to trip) - so much of what i wrote above probably still applies.

Kind Regards, John

 

[NowWhyisThat?]

Thanks John.
Its not happening often. Only sometimes. I know that intermittent faults are always the worst to accurately diagnose.
As I said, I’ve had an electrician thoroughly test my electrics and he said all was good from that perspective.
I’m not an electrician but I was simply wondering if a faulty on/off switch on a washing machine can cause an intermittent RCD trip-out on a modern washing machine, because the simple act of pressing that switch causes the trip-out.
And, confusingly, when I then immediately reset the RCD the machine then works perfectly with no further interruptions to the wash cycle chosen. From beginning to end all goes smoothly. A real head-scratcher. I’m convinced the fault lies with the machine. Just trying to figure out what that fault is most likely to be. If the on/off switch goes via the pcb board then I guess I’ll just buy a new machine. As a new board would cost upward of £130, and have already spent almost half the cost of a new machine on the Electrician visit as well as the washing machine engineer’s “failed” input.

 

[ericmark]

I have failed to do the checks I should, many times, as I simply never bought the meters needed to do the checks.

I have crossed my fingers, and changed RCD's to see if it helps, and it has, but not in hind sight convinced it was the RCD at fault.

The problem is an insulation tester uses DC, but our supply is AC, and with AC we have capacitive and inductive linking, which John refers to with the filter capacitor. We may be lucky and see the problem using a clamp on meter, with a 0.001 amp resolution, but a RCD should work in 40 mS so only real way is with an oscilloscope.

So in the real world we try to split the supply into circuits, so multi faults don't build up to a point where the supply will trip, but the more we split the more it costs, so in the past we have seen one RCD feeding many circuits, but once done we are looking at cost to change to all RCBO, specially as we don't know if doing so will help.

Normally I would say get an electrician to check, but you have already done that. So maybe start point is picture of consumer unit.

 

[NowWhyisThat?]

Hopefully photos attached. Thank you, sir.

 

[Wayners]

Loose wire in isolation switch. Check and tighten. Maybe

 

[NowWhyisThat?]

Thanks Wayne. Do you mean a loose wire in the machine?
Or a loose wire at the fused spur at kitchen counter level?
Socket into which the machine is plugged below the fused spur (and immediately behind the back of the machine) has been checked by electrician and no issues.

 

[JohnW2]

Thanks John. Its not happening often. Only sometimes. I know that intermittent faults are always the worst to accurately diagnose.

Indeed so.

As I said, I’ve had an electrician thoroughly test my electrics and he said all was good from that perspective.

Fair enough. Do you know if that testing included testing the RCD?

I’m not an electrician but I was simply wondering if a faulty on/off switch on a washing machine can cause an intermittent RCD trip-out on a modern washing machine, because the simple act of pressing that switch causes the trip-out.

I would say it's incredibly unlikely that the problem would be with the switch itself - much more likley that the trips are occuring because the machine is 'electrically connected when the switch is switched on.

And, confusingly, when I then immediately reset the RCD the machine then works perfectly with no further interruptions to the wash cycle chosen. From beginning to end all goes smoothly.

As I suggested, that would seem to suggest that the problem may be due to something that happens, very transiently (i.e. for a very brief period of time), when power is first applied to the machine.

If you had two (30mA) RCDs, the normal suggestion would be that you should try plugging the WM into a socket protected by the other one, to see if it still trips, but you appear to only have one.

A real head-scratcher. I’m convinced the fault lies with the machine. Just trying to figure out what that fault is most likely to be. If the on/off switch goes via the pcb board then I guess I’ll just buy a new machine. As a new board would cost upward of £130, and have already spent almost half the cost of a new machine on the Electrician visit as well as the washing machine engineer’s “failed” input.

Yes, it's difficult, so I'm not sure what to suggest that would be (cost) sensible for you (if it were me, I'd probably be looking at the WM myself!). Others may have suggestions.

Kind Regards, John

 

[RandomGrinch]

I'm not an expert, but I would go with JohnW's filter theory.

After the initial trip, the filter capacitors would be at least partially charged, and the circuit could be turned back on without another trip.
The mechanism of a switch acting (even an electronic one), would be unlikely to cause an RCD trip by itself.

Being an experimentalist , I would be tempted to bypass the the EMI filter (not strictly needed for the operation of the machine), and see what happens.

It could also be that other devices on the same circuit may have a small amount of earth leakage, a dodgy EMI filter on the washing machine may just push the RCD past the edge.

Some examples of EMI filters suitable for Samsung machines are listed here (mixed along with other 'filters'):

Samsung Washing Machine Filters | eSpares

www.espares.co.uk

 

[JohnW2]

.... The problem is an insulation tester uses DC, but our supply is AC, and with AC we have capacitive and inductive linking, which John refers to with the filter capacitor. We may be lucky and see the problem using a clamp on meter, with a 0.001 amp resolution, but a RCD should work in 40 mS so only real way is with an oscilloscope. ....

Indeed. Given that the problem is clearly a very transient one (since the machine works OK, without a further trip, once the RCD is reset) I suspect that it's very unlikely that any test instrument would be useful. Even a 'scope probably would not help much, not the least because it probably wouldn't be able to identify the actual source of a problem within the machine.

If it were me, I think that, having confirmed that the RCD was working satisfactorily, I think I would probably get into the WM and disconnect any input filter capacitors it had - and if that did not cure the problem would probably conclude, like the OP, that attempting to pursue a repair would probably not be cost-effective.

Kind Regards, John

 

[NowWhyisThat?]

Thank you, John, for your very detailed reply.
The electrician did indeed ramp test the RCD. Think he also carried out an IR test.
He unplugged/isolated all items plugged into the kitchen sockets while he did his checks at the CU.
No issues as far as he could see with my electric circuitry.
Would it be worth asking him, as a last ditch effort, to replace the RCD just in case the one currently in situ has suddenly become a little “trigger happy”?
As I think I’ve said, this problem has only arisen intermittently in relation to the WM power-up switch being pressed. Only that. Prior to this the last time I had an RCD trip out was around 4 years ago when the element in my dishwasher blew.

 

[SUNRAY]

My instant reaction to this is the mains filter, just as John says. It is the most common reason in washing machines and dishwashers for RCD tripping at switch on or off.

I have just replaced my washing machine and before it went out for the scrappies I removed the filter as a spare.

 

[JohnW2]

Thank you, John, for your very detailed reply.

You're welcome.

The electrician did indeed ramp test the RCD. Think he also carried out an IR test. .... Would it be worth asking him, as a last ditch effort, to replace the RCD just in case the one currently in situ has suddenly become a little “trigger happy”?

Given what you now tell us, I wouldn't think so. The problem was already happening when the electrician did his tests, so if a ramp test then was satisfactory, it is clear that the problem was occurring in the absence of a trigger-happy RCD.

As I think I’ve said, this problem has only arisen intermittently in relation to the WM power-up switch being pressed. Only that. Prior to this the last time I had an RCD trip out was around 4 years ago when the element in my dishwasher blew.

From where we are, we obviously can but guess/speculate, but if I had to 'put my money' on the most liklely explanation, it would probably be the filter capacitors - which is why I said that would be the next thing I would personally look at. However, given that there is definitely no certainty, whether it would be a sensible/cost-effective gamble for you to get someone to pursue that possibility is a different matter.

Kind Regards, John

 

[NowWhyisThat?]

Thanks again, John.
You, and the others who have responded to my query, have painted a very clear picture for a layman like myself to understand. Warmest wishes to you, sir.