Help with a tripping washing machine

[Chris Archer]

Hi Guys,
I'm having trouble diagnosing a fault on a customers downstairs socket ring, which only ever trips when the washing machine is used.
The fuse board is an MEM Memera 2000
the downstairs ring is on a 32A 60898 MCB, protected by a 61008 RCD 100A 30mA
there are 2 other circuits on the same RCD which are the upstairs rings on a 32A 60898, and the shower also on a 32A 60898

The customer had this problem before I came and had already tried replacing the washing machine and getting the same problem.

• we have carried out fault finding and also EICR'd the whole house with perfect results,
• we have tried plugging in the washing machine upstairs which is the same RCD and it didn't trip. and also on another circuit in the garage on a different RCD which also didn't trip (both times the washing machine stayed in the same position in the kitchen under the worktop and was just plugged into different sockets via an extension lead
• we have also tightened all connections on the downstairs ring assuming that maybe the washing machine vibrating could have caused a loose connection and tried fault finding again and cant find any problems
• we have also tested for overload by unplugging every other thing on the circuit and it still trips
• we have also replaced both the RCD and the MCB and still it keeps tripping
• I have tried plugging into other sockets on the same circuit and it still trips
• I have also tried replacing the socket its plugged into just in case

Yet we cant find any fault so I'm absolutely stumped, is there anything I've forgotten to do?

Thank you in advance, I'm loosing hair over this problem haha

Test results for Downstairs socket ring
R1 0.57
RN 0.57
R2 0.95
R1+R2 0.38
Zs 0.63
RCD 1/2x didn't trip
RCD 1x 27.8ms

 

[Pretty Mouth]

At what point of the WM cycle does it trip? Immediately or after a while?

Was the replacement RCD exactly the same one, or was another type substituted?

 

[loz2754]

I'm not seeing the most important test results in your list for that circuit.

 

[Chris Archer]

I'm not seeing the most important test results in your list for that circuit.

Sorry yes insulation resistance was also >999 at 500V

 

[Chris Archer]

At what point of the WM cycle does it trip? Immediately or after a while?

Was the replacement RCD exactly the same one, or was another type substituted?

Yes it was, I did however make a mistake the RCD’s are

At what point of the WM cycle does it trip? Immediately or after a while?

Was the replacement RCD exactly the same one, or was another type substituted?

The customer told me it trips virtually straight away as soon as the cycle starts,
I went to the property yesterday and it wouldn’t trip for me, however now that I’m thinking about it it was empty and not a full washing load when I tested it for overload,

Also the RCD was the same yes, although if it helps I did make a mistake it’s a BS 4293 type 2, not 61008 weather that makes a difference or not

 

[Pretty Mouth]

Sounds like the fault is intermittent, which means some of the things that have been tried may have given misleading results. Also sounds like it's unlikely to be a circuit fault, which points to either the RCD or WM (my money's on the latter).

Have you IR tested the WM itself? Good to do this immediately after the tripping event too, if possible. I would try leaving it plugged into one of the other circuits via extension lead for a week or 2, and see if it trips the RCD then.

 

[nicebutdim]

Recently traced a similar fault to an isolator switch. Everything pointed towards a faulty appliance, but it was fairly new and an expensive machine and I wanted to return to clamp it and check for leakage throughout the cycle. The switch didn't feel quite right (nothing obvious, but wasn't happy with its operation) and I decided to change it while there, for the sake of a few pounds. Previously the appliance had tripped about once in every three cycles and since hasn't tripped once in the last few weeks - maybe it'll act up again, but it appears as though I found the fault by accident and through sheer blind luck.

 

[Chris Archer]

Sounds like the fault is intermittent, which means some of the things that have been tried may have given misleading results. Also sounds like it's unlikely to be a circuit fault, which points to either the RCD or WM (my money's on the latter).

Have you IR tested the WM itself? Good to do this immediately after the tripping event too, if possible. I would try leaving it plugged into one of the other circuits via extension lead for a week or 2, and see if it trips the RCD then.

the customer has said she has tried it multiple times in a upstairs socket on the same RCD via extension lead and in a socket in the garage on another RCD and it didn’t trip,

But yes I will try IR the machine itself, it just seems very strange that it could possibly be a another faulty washing machine as she replaced it already due to this problem, and the last thing I want to do is sent her down the path of trying to have it replaced again and it still causes a problem,

Thank you very much for your help tho, I must admit it seems to me unless it is the washing machine again it has to be an intermittent fault, possibly due to the vibration while it has a full load, I just have no idea how to solve it as it I’ve already tightened all connections in every socket/spur in the kitchen

Other wise perhaps I’ll wire a dedicated supply for it

I also got her to try the kettle in the same socket today and that didn’t trip it

So I’m totally stumped haha
Many thanks for your help, I’ll go and try what you’ve said on Monday

Cheers
Chris

 

[Chris Archer]

Recently traced a similar fault to an isolator switch. Everything pointed towards a faulty appliance, but it was fairly new and an expensive machine and I wanted to return to clamp it and check for leakage throughout the cycle. The switch didn't feel quite right (nothing obvious, but wasn't happy with its operation) and I decided to change it while there, for the sake of a few pounds. Previously the appliance had tripped about once in every three cycles and since hasn't tripped once in the last few weeks - maybe it'll act up again, but it appears as though I found the fault by accident and through sheer blind luck.

Yes, I think I’ll also do that, perhaps although the connections are tight it could be a faulty fused spur and the problem only occurs when it’s heavily vibrating with a full loads,
Thanks for your help

 

[nicebutdim]

Yes, I think I’ll also do that, perhaps although the connections are tight it could be a faulty fused spur and the problem only occurs when it’s heavily vibrating with a full loads,
Thanks for your help

It's a long shot and the switch I replaced appeared fine visually, with all terminations sound and each conductor clean and bright. Now that I remember it was also a switched fused spur and in as new condition, other than some slight feel to the switch operation that wasn't quite right.

 

[Pretty Mouth]

the customer has said she has tried it multiple times in a upstairs socket on the same RCD via extension lead and in a socket in the garage on another RCD and it didn’t trip,

But yes I will try IR the machine itself, it just seems very strange that it could possibly be a another faulty washing machine as she replaced it already due to this problem, and the last thing I want to do is sent her down the path of trying to have it replaced again and it still causes a problem,

Thank you very much for your help tho, I must admit it seems to me unless it is the washing machine again it has to be an intermittent fault, possibly due to the vibration while it has a full load, I just have no idea how to solve it as it I’ve already tightened all connections in every socket/spur in the kitchen

Other wise perhaps I’ll wire a dedicated supply for it

I also got her to try the kettle in the same socket today and that didn’t trip it

So I’m totally stumped haha
Many thanks for your help, I’ll go and try what you’ve said on Monday

Cheers
Chris

Good luck with this. Out of interest, have you been able to re-create the fault yourself?

 

[mainline]

Hi Guys,
I'm having trouble diagnosing a fault on a customers downstairs socket ring, which only ever trips when the washing machine is used.
The fuse board is an MEM Memera 2000
the downstairs ring is on a 32A 60898 MCB, protected by a 61008 RCD 100A 30mA
there are 2 other circuits on the same RCD which are the upstairs rings on a 32A 60898, and the shower also on a 32A 60898

The customer had this problem before I came and had already tried replacing the washing machine and getting the same problem.

• we have carried out fault finding and also EICR'd the whole house with perfect results,
• we have tried plugging in the washing machine upstairs which is the same RCD and it didn't trip. and also on another circuit in the garage on a different RCD which also didn't trip (both times the washing machine stayed in the same position in the kitchen under the worktop and was just plugged into different sockets via an extension lead
• we have also tightened all connections on the downstairs ring assuming that maybe the washing machine vibrating could have caused a loose connection and tried fault finding again and cant find any problems
• we have also tested for overload by unplugging every other thing on the circuit and it still trips
• we have also replaced both the RCD and the MCB and still it keeps tripping
• I have tried plugging into other sockets on the same circuit and it still trips
• I have also tried replacing the socket its plugged into just in case

Yet we cant find any fault so I'm absolutely stumped, is there anything I've forgotten to do?

Thank you in advance, I'm loosing hair over this problem haha

Test results for Downstairs socket ring
R1 0.57
RN 0.57
R2 0.95
R1+R2 0.38
Zs 0.63
RCD 1/2x didn't trip
RCD 1x 27.8ms

I don't seem to see any earth leakage tests ?
Can you not try that ring on an rcbo ?.

 

[Chris Archer]

I don't seem to see any earth leakage tests ?

To be fair I haven’t Pat tested the washing machine itself, as the fault was there on the previous washing machine, and still there on the new one,
I will check that though,
Also the washing machine works fine on other circuits

 

[mainline]

To be fair I haven’t Pat tested the washing machine itself, as the fault was there on the previous washing machine, and still there on the new one,
I will check that though,
Also the washing machine works fine on other circuits

You need to find out what the accumulative earth leakage is.

 

[nicebutdim]

You need to find out what the accumulative earth leakage is.

OP stated that machine was tested on another circuit covered by the same RCD and didn't trip. Not conclusive, but suggests that cumulative earth leakage may not be the issue.

 

[mainline]

OP stated that machine was tested on another circuit covered by the same RCD and didn't trip. Not conclusive, but suggests that cumulative earth leakage may not be the issue.

He still needs to know what the accumulative earth leakage is.

 

[nicebutdim]

He said it works fine on another circuit, which means that the circuit its on now could have higher accumulative earth leakage than the other circuit.

Actual statements from opening post below:

• we have tried plugging in the washing machine upstairs which is the same RCD and it didn't trip. and also on another circuit in the garage on a different RCD which also didn't trip (both times the washing machine stayed in the same position in the kitchen under the worktop and was just plugged into different sockets via an extension lead
• we have also tested for overload by unplugging every other thing on the circuit and it still trips
• I have tried plugging into other sockets on the same circuit and it still trips

The last point would also seem to rule out my (already unlikely) suggestion that isolator could be problematic.

 

[mainline]

Actual statements from opening post below:



The last point would also seem to rule out my (already unlikely) suggestion that isolator could be problematic.

Although IR tested, it still doesn't rule out that earth leakage could happen when a load is put on that circuit.
Therefore, an earth leakage test would be the next step.

 

[nicebutdim]

Although IR tested, it still doesn't rule out that earth leakage could happen when a load is put on that circuit.
Therefore, an earth leakage test would be the next step.

It would be a sensible step to rule out the possibility, although tripping seems to be limited to this one circuit and tripping continues with all other loads disconnected. As such cumulative leakage doesn't appear to be the issue if this machine trips when no other loads are present and leakage from machine itself appears to be no issue when connected to other circuits. That this applies on circuits protected by same RCD would suggest overly sensitive RCD is also unlikely to be the problem.

Whatever the issue, OP's efforts would seem to suggest that it stems from the circuit to which the appliance is normally connected.

 

[mainline]

It would be a sensible step to rule out the possibility, although tripping seems to be limited to this one circuit and tripping continues with all other loads disconnected. As such cumulative leakage doesn't appear to be the issue if this machine trips when no other loads are present and leakage from machine itself appears to be no issue when connected to other circuits. That this applies on circuits protected by same RCD would suggest overly sensitive RCD is also unlikely to be the problem.

Whatever the issue, OP's efforts would seem to suggest that it stems from the circuit to which the appliance is normally connected.

I'm wondering if the OP did an N + L 250v IR test ? That would give an indication that all loads are indeed disconnected.