Split-load Switch / RCD flipping down repeatedly

[dpm_dpmartin]

Hi all,

I am not preparing to do any work myself - this is beyond me - but I'd appreciate any thoughts about it so I can have a useful discussion with an Electrician when one eventually comes to visit.

My consumer board has a number of separate circuits and 2 x 80A 30mA RCDs... one of the RCDs is flipping now and again - taking out half of the house (ground floor lights, first floor sockets, boiler, oven and a circuit with no label I assume is the outside socket that we had put in about four years ago).

None of those circuits to the left of it are flipping (none at all in the consumer board are). I thought if there was a problem with an appliance or circuit then the circuit would trip / flip, identifying the problem... but it's just the RCD on its own. All other circuits remain up.

Do RCDs age with time and they just sometimes need replacing, or does an RCD that flips indicate some kind of real problem somewhere, as yet unidentified? Is there any benefit to turning off specific circuits for, say, a day at a time and seeing whether that influences the RCD itself tripping / flipping - or - because none of them are doing anything anyway would it be a pointless exercise?

I have pressed the yellow button to test the RCD and it worked just as it should - half the house went down and I flipped it back myself.

No recent work has been conducted.

 

[Murdochcat]

Unfortunately what you are experiencing can be caused by a number of different issues.

The best thing you can do is keep a log of when it trips to see if there is any pattern before you call anyone as they will be asking this

 

[dpm_dpmartin]

Understandable - and helpful, thanks. The latest occurrence, noticed this morning, was clearly sometime overnight... so everyone was asleep and woke up to find the RCD - alone - had tripped.

 

[Murdochcat]

Electrics outside? boiler coming on? Immersion coming on? Fridge or freezer starting up?

 

[dpm_dpmartin]

Exactly, at this stage I have literally no idea... it's been happening for about a week... but not every day even, and sometimes multiple times in one day... I'm starting to think weather-related even. If only one of the actual circuits had tripped to provide a clue.

 

[Murdochcat]

The RCD is "shared" and is detecting earth leakage from any of the connected circuits.

We have had a lot of rain lately and do you have rodents?

 

[dpm_dpmartin]

There's no sign of rodents (but we do live on the edge of a park), but there's been plenty - plenty - of rain - and that's even more worrying, I guess.

 

[Murdochcat]

Also bear in mind with a few circuits on a shared RCD, you can suffer from cumulative leakage where the more you switch on can tip the RCD into tripping. These days no spark with any sense installs dual RCD or high integrity consumer units.

That said over night tripping should help you narrow it down.

Have you go any new appliances / electronic equipment recently?

 

[dpm_dpmartin]

Well, we did get a new telly - that was about 3 or 4 weeks ago - that telly is on the other unaffected RCD so I thought nothing of it. I think I will start to turn off circuits one by one... and start to maintain some kind of log (assuming it will continue happening).

Everything has been fine for a decade... and now one RCD is tripping multiple times per day some days, that's why I'm scratching my head, and trying to obtain a better level of knowledge / some understanding.

As for overnight... I'm thinking boiler. It can't be the oven, and the fridge and freezer would be on ground floor sockets or kitchen sockets - both on the other RCD.

 

[dpm_dpmartin]

These days no spark with any sense installs dual RCD or high integrity consumer units.

I don't have any insight into that... but it definitely does have dual Wylex WRS80/2 RCDs... it was probably installed around 2010 / 2011.

 

[bernardgreen]

The RCD is tripping due to current flowing to Earth from either the Live and/or Neutral.

Turning OFF the MCB on the faulty circuit will not stop the fault tripping the RCD.

Many people including some "qualified" electricians believe that if an RCD trips when an MCB is switched OFF then the fault cannot be on the circuits fed by that MCB.

 

[baldykev]

check the outside socket for water ingress and any outside lights make sure you isolate power before hand

 

[ETAF]

unplug every thing on the circuits that are tripping. make sure its everything

My son-in-law had this for a few days and the first thing I told him to go through removing all plugs , still intermittently tripped , and this was over a weekend,
was going to call out an electrician but quotes of £150 - £200 call out charge and free 15mins and then £100 an hour !!!!!!!!!!
In the end found that daughter had an old hairdryer , which she had been plugged in and was under bed - he missed this
Also my son had a laptop lead - just the power part plugged in, no laptop connected and that tripped the RCD intermittently

any outside light - full of water ???

is the boiler plugged in to a 13A socket or on an isolator

 

[dpm_dpmartin]

Turning OFF the MCB on the faulty circuit will not stop the fault tripping the RCD.

Thank you, that certainly would've been what I assumed too.

 

[dpm_dpmartin]

a) there are 3 outside lights, some are high up, but I will try and check
b) I can easily check the outside socket
c) the boiler is not on a 13A socket, it is on a fused spur (a white box with wires and a rectangular place for a fuse to go)

The intermittent-ness of this certainly has me worried about water ingress somewhere.