Another RCD Tripping problem

[eskimo39]

Hi guys, last week my neighbour asked me to look at their consumer unit as it had tripped 4 times in one day.
The side that tripped had on it:

• Kitchen Sockets (1xMicrowave, 1xFridge, 1xFreezer, 1xKettle & 1xWashing Machine)
• Hob
• Upstairs Lighting

I tested the RCD and it tripped in 26ms and a ramp test showed 29mA so it looked like it was o.k.

I thought the fault would most probably lie with one of the appliances and with the washing machine having a heating element in it, assumed this the most likley. I explained if it tripped again they should plug the washer into an extention lead and power it via the living room sockets from the other RCD. If this didn't work, I planned on trying the other appliances.

However the RCD tripped so they unplugged the washer and powered it from the living room sockets as discussed. After a while this tripped the other RCD so I thought that had solved the problem and it was the washing machine. However 5 minutes after, with the washer still on the living room RCD the original RCD also tripped??????

Does anyone know what could be causing this? I thought when the other RCD tripped via the extension lead that would have meant the washer was at fault. 5 minutes later the original RCD tripping has put doubts on this.

Does anyone have any other ways to test???

Cheers

 

[Deleted member 9648]

You need to do an IR test on the circuits with all appliances unplugged and disconnected...if this is clear then IR test appliances.
This is always the first step,otherwise yiou are just guessing.

 

[eskimo39]

I have never IR tested appliances before, can this be done with a Fluke 1652B? Is it just a case of clipping the probes to the L & N pins on the plug and using a 250v test?

 

[jmtisme]

I think he means IR the circ. Not the appliances.
Is the problem not on the lighting circ.

 

[Andyfm]

I would do an IR test L- E then N - E as soon as you could after it tripped with the appliances still plugged in/switched on at 250v and see if theres any low readings , if there are then go round switching off/ unplugging the appliances (as some sockets are single pole switching) hopefully find what clears the low readings - if it doesn`t clear then start testing the cabling -

 

[eskimo39]

If it was on the lighting I wouldn't have thought it would have moved to the other RCD when we changed where the washing machine was plugged in. Have just been around now and all curcuits are clear on IR test (includng lighting & hob).

What also makes it difficult is that it doesn't wlways trip, sometimes it stays in for hours and other times minutes.

I thought I had it solved when the otherside tripped with the washer plugged in but then for the original side to trip again aaaaaarrrgh

 

[wattsup]

is it a German rcd?

 

[8145keith]

Hi mate,

Are all the appliances old, sounds like possibly more than one faulty appliance.


If all circuits are showing hi resistance to each other, then I would get the customer to unplug equipment not in use, this way you will shorten the list of possible cause.


Also make sure all neutrals are tight in the fuse board, and no evidence of over heating, due to loose cables.


Last one, is it a rural location, once had a squirrel eating the loft cables years ago, took ages to find it.


Hope this helps regards KJ

 

[Andyfm]

Haven`t got a leaky roof or pipe somewhere and water occasionally getting into jb or lighting connection in loft , or maybe vermin having a nibble on the cables

 

[eskimo39]

Hi guys, thanks for all the responses. IR testing on all circuits came up fine. Also once we changed the washing machine to a socket powered by the other side of the board via the extension lead, that side tripped first so the chance of lighting being at fault on the other side would be limited I'd have thought.

I did check all connections when first around there and all fine.

In 3 years my neighbour had never had either RCD trip and it was only last week that one side went, she reset it and had to do so 3 more times throughout the day.

What I am struggling to get my head around is the other RCD tripping when we changed over the washing machine, this would obviously have happened if the machine was faulty. However I am confused as to why then the original RCD tripped 5 minutes later when it was on the other side of the split board??

Is there a way to test appliances for faults with a fluke 1652B??

Thanks again for all your help

 

[wattsup]

washing machines, fridges/freezers and ovens are always the first port of call, pat test them by all means, but often it depends which cycle the appliance is on. Ovens are a pain with dodgy stats, sometimes the fan...toasters, a bread crumb to element/earth.......fridges are hard to solve, motor / stat. test with fridge doors open and leave for 5/10 mins. Washing machines impossible unless you go through each and every function, may take hours!

Even then if its an intermittent fault you won't find it...i know customers get narked...well it was ok before (when on an old wylex db or similar) its hard to justify and explain, half the time they don't believe your explanation anyhow.

I know a washer repair man, he has never been so busy these past few years, most times its simple condensation probs.....he loves rcd's

 

[wattsup]

Assuming wired by a qualified electrician, the fault is 99% chance of being an appliance, I've had brand new stuff at fault, even a brand new light fitting, even brand new electronic dimmers.

I once worked at a major store about 20 years ago....just when elf and safety began to kick in, they wanted lighting dept rcd protected , it may have been elcb protected at that time, can't remember...
Anyhow I thought this will be fun, the store was wired concentric in mi..oops, it aint gonna work

 

[wattsup]

When I pointed this out, the store was promptly rewired 12-months later at a cost of £200,000 lot of money then, i didn't even get a thank you

 

[eskimo39]

Cheers Guys,

I am 99% certain the fault is an appliance, the only puzzle is why when the washing machine was put on a socket powered by the other side of the board, it tripped as expected but then the original side tripped as well???

 

[gawain]

what ive heard alot of are rcds tripping over light bolbs that are blown maybe you can check is the light bulbs are all working. rcds are very sensitive.