18 Jan 2019
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United Kingdom
Washing machine motor went and tripped RCD.

Washing machine 12yr old so thrown.

Replace with one from daughters flat when new kitchen fitted. This washing machine been in dry garage for 4yrs but worked fine when removed.

Fitted replacement machine and tripped RCD.

Plugged machine via ext lead to another circuit with separate RCD. worked fine!

Used socket tester on every socket in utility room and all pass polarity, loop and RCD test. Replaced RCD with new and same problem.

Removed lives at consumer unit and checked continuity - OK.

Opened up every 13A socket in utility room looking for anything obvious, tested for continuity by removing both live and com at each socket and all OK.

Down to thinking there has always been a small earth leakage say 15milli amp on socket ring main and washing machine also has a small one that causes it to exceed the rated 30 milli amp rating of the RCD.

Any other suggestions. Where do I go from here? Old machine worked fine for 12yrs. Replacement works fine when on another RCD circuit.

Would really love to avoid buying new washing machine when it works fine when plugged into another RCD circuit
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did you unplug everything

yes, everything

everything including your computer and TV

from the socket circuit? And did the RCD still trip when the w/m went on?

Did it trip during the heating cycle (only)?

Does that circuit supply any outside circuit or outdoor lighting?
No I did not unplug everything.

RCD only trips when washing machine plugged in on this circuit BUT RCD on another circuit does not trip when washing machine plugged into this other circuit?

Will try to unplug everything and just plug in washing machine assuming something is adding to possible small earth leakage on washing machine.
yes, unplug the lot, then plug them in, either one at a time or half at a time. You may well find that certain appliances are giving the leakage.

Your computer is likely to be one; so is anything with water in it, such as the boiler, kettle, fishtank, tea-urn.
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The cu only has 1 rcd?
So why when using another circuit on same rcd is it ok?

Maybe quicker to fit a new radial for the wm!!??

Replace wm socket?
One thing I have found is that 13A fused spurs are marked IN and OUT rather than SUPPLY and LOAD and the N positions are reversed on fused spur with IN at bottom and OUT at top.

As it's a double pole switch(simultaneously switched both L and N on or off) I assume it makes no difference.

Any comments?
it matters most if they have an on/off neon.
No neon on fused spurs and RCD does not trip switching either on or off.

Now stripped down every fused spur and power point in utility room and possibly one connection on N at a 13A power point with a fused spur connected hence 3 N wires was "possibly" slightly loose - been checking each one by trying to pull out individual wires with pointed pliers.

All now all refitted and RCD has not tripped on plugging in spare washing machine. Unfortunately have plugged it in before and even completed 2 wash cycles without tripping! Fault always easier to find when constant.

Came to conclusion that problem was small individual earth leakages over all circuits was additive and exceeding 30.

Wondering if as no problem at this moment something is not currently switched on yet RCD will cut out when it is!

If additive leakage and I have a spare RCD wondering if dividing up MCBs at consumer board between 2 RCDs.

Interested in others comments.
RCD just tripped after 15min with machine switched on but not working. There are only 3 circuits on this RCD.

Isolated gnd lighting and currently doing a wash cycle. So far all working.

Will wait 1hr then switch back on gnd lighting. I have removed external porch light that is exposed to damp from lighting circuit.

Again no one items appears to be the cause must be additive minor leakage faults.
Last edited:
A Neutral to Earth fault on a circuit can still cause an RCD to trip even if the MCB for that circuit is switched OFF. The trip occurs when there is a load on another circuit. Switching the MCB to OFF does not isolate the circuit as the Neutral is still connected to the Neutral bar in the Consumer Unit.

rcd trip 2018.jpg

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