Electrical advice: Washing machine tripping RCD

[kalicoorguk]

Out of the blue, my faithfull old Hoover washer tripped the RCD on my consumer unit.

After reset, it'll stay untripped when the machine is powered on at the socket, but as soon as I turn the control to anything other than 'off' the RCD trips.

The strange thing is that I've left the washing machine unplugged and yet the RCD still tripped a couple more times, but seems to have settled now and been ok for a few hours.

So, two questions:-

1. Any idea why the RCD might be tripping when machine is not plugged in (I'm assuming it is the machine that is faulty)

1. Assuming the machine is faulty, anyone know where to start looking for what could be causing the imbalance? Don't want to invest in a new machine if this one could be fixed easily/cheaply.

Note that the ring main MCB is not tripping, just the RCD for all the downstairs breakers.

I have electrical knowledge and multimeters etc. Just seeking opionions on what might be most likely.

Thanks, as always, for sharing your knowledge and experience.

[Andy Burns]

could be leakage of the mains filter in the machine, if you test on the plug of the washing machine, what impedance do you see across E&L, and E&N ... megger would be better than a multimeter if you have one.

Could be a chafed cable connection e.g. neutral to earth (if it was live to earth or to neutral it would be fuses or MCBs tripping)

[The Natural Philosopher]

You have an 'almost' trip somewhere else.

The washing ,machine is simply taking it over te dege

In my case the last two times it has been water on electrics due to plumbing leaks.

That may not be a valid assumption

[The Natural Philosopher]

Did you read the bit where he said 'it tripped with the washing machine UNPLUGGED

Clearly the fault is not with the washing machine: that is simply the trigger.

[Bob Minchin]

The RCD is looking as the cumulative earth leakage across all the circuits connected to it. So it is likely that several items are adding up to enough to cause a trip but no one item will be enough to trip it.

Progressively test the leakage of the likely culprits one at a time. best to do the tests at mains voltage or with a megger tester as many leaks will be voltage dependent and your LV ohm meter possibly will not show up a fault.

Things with heating elements are worth looking at first cooker rings, oven, dishwasher, immersion etc Second are things with RFI filters in where capacitors have gone leaky.

[T i m]

<snip>

When mine was doing that it was carbon (brush) dust on / around the motor and blowing it out with a compressor fixed it.

In our case it was tripping when power was supplied at the wall,

*even* if the machine was off.

Cheers, T i m

[Brian Gaff]

More likely to be a pin hole in a hose near some electrical part. After all those internal hoses do get a pounding on spin you know. I'm rather intrigued by the memory effect of your cut out device myself. Are we totally sure that the device itself is not suddenly ultra sensitive. Any chance of swapping one from another circuit to prove its the appliance given the trips when the device is unplugged. Brian

[tabbypurr]

Look for the faulty appliance(s) by resistance testing from L+N to E or case with it unplugged & its power switch on. Using a multimeter will often pick up leaky items, a megger more reliably does.

NT

[Brian Gaff]

Yes also any anti surge socket bars as well. Brian

[Brian Gaff]

No you have a cumulative issue here. Not just one device. I'd most certainly remove everything of that ring and test the washer on its own. Brian

[Bill Wright]

Either something else leaking and the washer just takes it over the threshold, or, more likely, a faulty RCD.

Bill

[2987fr]

No, because it has tripped with the washer not even plugged in.

if you test on the

[T i m]

I didn't suggest otherwise Brian. However, if the WM causes an overload it could well also be part of the problem.

Cheers, T i m

[kalicoorguk]

Wow! Just wow! Thanks so much guys - this is all really good advice.

It did strike me that it could be the RCD at fault. I will run a long cable to a socket that's hung off the other RCD and see if the washer still trips it. I can also plug the washer directly into a portable 30mA trip RCD.

The suggestion re carbon in the motor could well be worth looking at. I reaplced the brushes in the motor with new ones about 3 months ago, so it could be 'dusty' in there. That said, it trips even when the control knob is set to somethign that doesn't immediately run the motor.

Classic case of trying to think what else has changed, isn't it. There are some recenlty fitted under-cupboard/over-worktop lights. They seemed decent fittings when I bought them, but after running for a few hours, the 20W Halogen G4 bulbs caused some of the plastic to melt. Nice huh! I've replaced them with 1.7W LED lamps, so they will run cooler. But that was done 2 days ago, so maybe a culprit. (Though they were all switched off when the trip happened. It looked very much like the washer tripping it, but there are some good points here about why the washer might be just taking it over the edge).

Thanks to all - I will report back in the morning. Cheers

[T i m]

<snip>

Mine was as I saw when I blew it out (outdoors).

I think one side of he motor can be energised, even if it isn't actually doing anything and that can then cause a leak to ground.

A (potentially) simple test would be to unplug the motor (often a plug on the side or end of a short cable) and see what happens then. No RCD trip the chances are it is the carbon issue.

Cheers, T i m

[Harry Bloomfield]

Be aware that a neutral to earth leakage can also cause a trip, not just a live to earth leakage - many people forget this. So even an item turned off/ live disconnected can still cause an RCD to trip if it is plugged in, yet turned off.

[Bob Eager]

Doesn't really apply to the OP. Unless there is a magic earth/neutral connection when unplugged.

[The Natural Philosopher]

Two things have tripped me up before.

1/. Neutral earth shirt somewhere. 2/. Water on wiring somewhere.

Bothe of these make the whole system more senstive, but do not necessarily flip the trip.

Actual hard cases of serious appliance earth leakage have been somewhat less.

[T i m]

But how would that apply to:

"Out of the blue, my faithful old Hoover washer tripped the RCD on my consumer unit.

After reset, it'll stay untripped when the machine is powered on at the socket, but as soon as I turn the control to anything other than 'off' the RCD trips."

The WM *must* be playing a part, even if it isn't the only player?

And can we assume this hasn't always been the case and may have some connection with the OP recently changing the brushes (and therefore the previous brushes would be spread inside the motor and surroundings)?

Cheers, T i m

[Harry Bloomfield]

Bob Eager used his keyboard to write :

I did spot that, but worth pointing out anyway as it causes so much regular confusion.