RCDs tripping during heavy rains

[meu10140]

Hi all - hopefully you can forgive my lack of knowledge on electrics, I have a basic grasp but am no expert.

The issue I've had and am looking for an initial steer on is that during some extremely heavy rains recently, after a long spell the RCDs will trip. While still raining, they will not be able to be reset, but a little after it stops, they can be, and work fine.

As a bit more info, this is in a top floor apartment, and there is a very small amount of visible water penetration during heavy rains over the main door from the stairs, which is in the vicinity of the Consumer Unit, and likely where the main incomer passes.

I've read through the other posts on RCDs tripping here, and it sounds like there could be a number of things. Given that it's the RCDs that are tripping (and not always at the same time), I think the issue has to be downstream of the CU. But thereafter, I'm guessing that the fault could be anywhere. All appliances work fine under normal conditions, no tripping. So I'm thinking that there is some faulty cabling going through an area that during rains is getting wet enough at some point to cause some current leakage to something, and trip the RCD. And then once the moisture dissipates, the leakage goes, and can be reset without issue. And if this is the case, then it's very difficult to pinpoint, therefore meaning I could be in for a full rewire?

At the minute the CU has two banks of circuits, each covered by an RCD, so I'm wondering if in lieu of full rewire it would be easier to change the CU and layout so each circuit has it's own RCD, which would then at least focus the issue, and stop me losing full electrics hopefully when this issue arises, until such time as I can resolve the externals to stop water penetration 100%. I'm concerned about the full rewire as there are a lot of original walls which the cabling will be chased into, which is obviously messy work and it'll tear the place apart to have to do so.

Any ideas on how you would start with this type of issue? Many thanks in advance!

 

[buzzlightyear]

You need to employ a spark to investagate why it's tripping.

 

[Pete999]

Hi all - hopefully you can forgive my lack of knowledge on electrics, I have a basic grasp but am no expert.

The issue I've had and am looking for an initial steer on is that during some extremely heavy rains recently, after a long spell the RCDs will trip. While still raining, they will not be able to be reset, but a little after it stops, they can be, and work fine.

As a bit more info, this is in a top floor apartment, and there is a very small amount of visible water penetration during heavy rains over the main door from the stairs, which is in the vicinity of the Consumer Unit, and likely where the main incomer passes.

I've read through the other posts on RCDs tripping here, and it sounds like there could be a number of things. Given that it's the RCDs that are tripping (and not always at the same time), I think the issue has to be downstream of the CU. But thereafter, I'm guessing that the fault could be anywhere. All appliances work fine under normal conditions, no tripping. So I'm thinking that there is some faulty cabling going through an area that during rains is getting wet enough at some point to cause some current leakage to something, and trip the RCD. And then once the moisture dissipates, the leakage goes, and can be reset without issue. And if this is the case, then it's very difficult to pinpoint, therefore meaning I could be in for a full rewire?

At the minute the CU has two banks of circuits, each covered by an RCD, so I'm wondering if in lieu of full rewire it would be easier to change the CU and layout so each circuit has it's own RCD, which would then at least focus the issue, and stop me losing full electrics hopefully when this issue arises, until such time as I can resolve the externals to stop water penetration 100%. I'm concerned about the full rewire as there are a lot of original walls which the cabling will be chased into, which is obviously messy work and it'll tear the place apart to have to do so.

Any ideas on how you would start with this type of issue? Many thanks in advance!

Sounds like you have water ingress into your flat, getting stuff damp and causing the RCD to detect a fault due to damp in your flat, need to call an electrician to survey the problem.

 

[loz2754]

The water could even be inside the consumer from the way you describe the issue.
First port of call is to have an electrician in to assess the situation.

 

[brianmoooore]

You need to employ a spark to investagate why it's tripping.

You need to employ a builder to investigate where the rain's coming in.
IP20 electrics and water don't go together.

 

[telectrix]

You need to employ a builder to investigate where the rain's coming in.
IP20 electrics and water don't go together.

a builder???? bugger that. end up with more problems than he started with. get a sparks in first. find out where the problem is, then get bob the builder to fix the leak.

 

[buzzlightyear]

You need to employ a builder to investigate where the rain's coming in.

Investigate first knock out wall after.

 

[meu10140]

Sounds like you have water ingress into your flat, getting stuff damp and causing the RCD to detect a fault due to damp in your flat, need to call an electrician to survey the problem.

Thanks all for the quick responses! Yes, 100% the issue is caused by water ingress. I'm just wondering how an electrician would approach this. And I have the issue that it only occurs after a sustained downpour, so getting a electrician out at the time of it tripping is a near impossible thing to try and time. For example, yesterday when this occurred was late at night during a heavy storm (weather warnings and all the rest) - not something that is predictable. If I can get someone out when it's tripped, then surely you can't work as there is water ingress around the CU and it's not safe, and at any other time the fault is gone, so impossible to diagnose.

I completely understand that this is in need of a good, qualified spark, but I'm just conscious that if I call them now, when it's dry and the issue is not present (which is 99.9% of the time), they wouldn't have much to go on. Which could mean that we'd end up just looking and saying, 'yes, there must be an issue, but no way of finding out where'.

Investigate first knock out wall after.

Out of interest, how would an electrician go about diagnosing this? Take apart the CU and inspect? Like I say, under normal conditions there are no issues and all works fine. Are there other ways to test circuits for faults that would trip an RCD that can be done non intrusively?

Thanks again.

 

[buzzlightyear]

Are there other ways to test circuits for faults that would trip an RCD that can be done non intrusively?

Test gear, and a good eyeballs.

 

[LastManOnline]

Hi all - hopefully you can forgive my lack of knowledge on electrics, I have a basic grasp but am no expert.

The issue I've had and am looking for an initial steer on is that during some extremely heavy rains recently, after a long spell the RCDs will trip. While still raining, they will not be able to be reset, but a little after it stops, they can be, and work fine.

As a bit more info, this is in a top floor apartment, and there is a very small amount of visible water penetration during heavy rains over the main door from the stairs, which is in the vicinity of the Consumer Unit, and likely where the main incomer passes.

I've read through the other posts on RCDs tripping here, and it sounds like there could be a number of things. Given that it's the RCDs that are tripping (and not always at the same time), I think the issue has to be downstream of the CU. But thereafter, I'm guessing that the fault could be anywhere. All appliances work fine under normal conditions, no tripping. So I'm thinking that there is some faulty cabling going through an area that during rains is getting wet enough at some point to cause some current leakage to something, and trip the RCD. And then once the moisture dissipates, the leakage goes, and can be reset without issue. And if this is the case, then it's very difficult to pinpoint, therefore meaning I could be in for a full rewire?

I agree with the previous posters that it's almost certainly going to require a professional to help you here. You did well to begin the faultfinding process by noting the pattern of the intermittent fault which is clearly related to heavy rain. 90% of these faults are related to outside lights, usually garden lightds but obviously a top floor apartment won't have too many of those. Any wall lights on your rcd?. If you have none of the above than time to call in a spark and having him around while the fault is still IN the system will save you and him headaches

 

[ruston]

Any water ingress around or in the consumer unit will leave clues . A good electrician will find it. You should not have to wait till it is tripping.

 

[Deleted account]

Any water ingress around or in the consumer unit will leave clues . A good electrician will find it. You should not have to wait till it is tripping.

Not always true.
if it’s intermittent it can be a bit of a b*gger to find sometimes.
testing can Sometimes show nothing out of normal when it’s not raining. just one drip of water or ingress to a certain point may be the cause.

 

[GBDamo]

Thanks all for the quick responses! Yes, 100% the issue is caused by water ingress. I'm just wondering how an electrician would approach this. And I have the issue that it only occurs after a sustained downpour, so getting a electrician out at the time of it tripping is a near impossible thing to try and time. For example, yesterday when this occurred was late at night during a heavy storm (weather warnings and all the rest) - not something that is predictable. If I can get someone out when it's tripped, then surely you can't work as there is water ingress around the CU and it's not safe, and at any other time the fault is gone, so impossible to diagnose.

I completely understand that this is in need of a good, qualified spark, but I'm just conscious that if I call them now, when it's dry and the issue is not present (which is 99.9% of the time), they wouldn't have much to go on. Which could mean that we'd end up just looking and saying, 'yes, there must be an issue, but no way of finding out where'.


Out of interest, how would an electrician go about diagnosing this? Take apart the CU and inspect? Like I say, under normal conditions there are no issues and all works fine. Are there other ways to test circuits for faults that would trip an RCD that can be done non intrusively?

Thanks again.

There may be visual clues like water staining or corrosion at the affected area.

Finding the affected area when not tripping is where the problems begin.

I've done many of these and sometimes you get lucky and find a leaky outside light or a rusty backbox and socket.

There are tests that can be done that may give an indication but only may.


My favourite,

A dentists that found their sockets would trip on Fridays occasionally. Would call the fault in and by the time an electrician attended it reset, every time.

I got approval to go in on a Saturday and do a lot of testing and found that the Insulation Resistance of all the cables was very good with the exception of one section of the socket ring.

It still worked but was significantly lower than everything else.

The cleaner popped into the room to change the air fresheners (???) and commented that it "didn't smell too bad in here today"

Whats this about a smell I asked, "Oh it usually stinks in here"

Found a section of floor, under a cupboard, I could lift and....

...yes, under the floor was full of sewerage..gip gip puke.

It was slowly filling up over the week, probably submerge a junction box and trip, and would seep away over the weekend.

Wasn't going to mess around so just disconnected the section and rewired it on the surface in trunking.

Apparently the turd herders had to pump 20,000 litres of sewerage and scrape a couple of tons of solids out from under the floor before finding a completely sheared soil pipe.

I always think of those poor sods when wallowing in a pit of self pity about having to work in the rain or somesuch.

 

[ruston]

@Paignton pete
I take your point , but he says -As a bit more info, this is in a top floor apartment, and there is a very small amount of visible water penetration during heavy rains over the main door from the stairs, which is in the vicinity of the Consumer Unit, and likely where the main incomer passes.
He also indicates that both RCD's are tripping.

 

[LastManOnline]

The water could even be inside the consumer from the way you describe the issue.
First port of call is to have an electrician in to assess the situation.

Any water ingress around or in the consumer unit will leave clues . A good electrician will find it. You should not have to wait till it is tripping.

That is true. A quick visual will establish. In practice it is rare for the issue to be at the CU as the physical distance between the conductors( Lives and earths) tends to not lend itself easily to these types of faults. Often however the distance between socket neutral and earth bar is close and worth investigating. Neutral earth faults don't tend leave conspicuous marks like a live earth fault would so a keener eye is required