Rcd trip

[fever28]

Any trouble shooting I can do?
I'm "ok" with electrical can do anything outside of CU

Did have electrician in last week who moved a couple of frequent tripping circuits off RCD (downstairs lights, bedroom sockets) fitted a new rcd too.

Issue now is it still trips when load increases, ie. shower on cold fine shower hot. It trips, heating on trips after an you, oven trips when you turn it up, kettle can trip it, plugging a lamp in can trip it, all very random. Things that trip can be got to work if I turn other things off.

It is only the rcd that trips

Done simple socket wiring test on every socket. Ok

We have three showers, one of which is decommissioned. Other two now trip every time hot water selected, unless everything in house is switched off.

Will get electrician again, but really just for hard or dangerous stuff. I can use a multimeter, re wire a socket, fit a shower etc..

Trouble shooting tips wanted. Just to isolate.

Cheers

[fever28]

It has gotten worse over last month, which sort of coincides with heating coming on, but heating works fine if I turn other. Stuff off.

[New Judge]

I’m not a qualified domestic electrician but I “dabble” (perhaps the wrong term to use when talking about electricity, but I spent a couple of years of my early working life making electrical things work in difficult circumstances).

An RCD works by measuring the current on each leg of the circuit and if one exceeds the other by more than (usually)30 milliamps it trips. This is a very strange problem you have with an increased load on the total supply tripping the RCD, especially when those increases come from varying sources (and which I assume are on different circuits off your distribution board).

I assume you have a “whole house” RCD and not individual ones for each section of the supply. If so, the problem could be caused by a slight earth leakage somewhere on the “common” part of your supply. It could be that under steady load the leakage is not bad enough to take 30 milliamps from one leg to earth but a sudden surge (especially through devices that have quite high resistance) is enough to do so. I don’t think this will be easy to identify yourself. I reckon the only way to determine this is to get an electrician to test the supply with decent Earth Leakage Detection equipment.

Not much help to you, I’m afraid, but my view is that you will find this problem hard to solve yourself.

[The Builder]

You need to explain a couple of things first, Fever.
"frequent tripping circuits" ........ how do you know it's these circuits? An RCD will disconnect ALL the circuits that it protects. How do you know these circuits are at fault?
Describe your CU .......
single RCD with MCBs on each circuit?
single RCD with fuses?
Split-load CU with 2 banks ........ both RCD protected?
RCBOs on each circuit? (RCBO is a combined MCB/RCD for a circuit)

When I've had this before, it's been either earth current leakage from cookers/fridges/freezers ................. or ........ faulty RCD tripping at, say 15mA rather than 30 mA

Also, only last week, someone complained of all the various random symptoms you describe. Then ............ hubby took a shower upstairs (poor silicone joint against wall). Then I noticed water dripping out of a downstairs light pendant ............ problem solved :o)

[buildersmate]

Good answers from the other two.
To summarise:
1) You can't a simple multimeter to fault-find an earth leakage issue.
2) Every circuit has a tiny miniscule leakage (measurable as microamps), but 30mA total leakage across the CU is the trigger point of the RCD. Favourite devices that often malperform and increase their leakage to earth are showers, CH pumps, CH boilers, cookers. It sounds like you have more than one device with a marginal performance and the combination of several leakages is exceeding the 30mA trigger point.

[BRIGHT SPARK]

Did your electrician issue certification when he done the circuit changes.

[fever28]

How do I know which circuits frequently trip. When the rcd goes, I have to flip the switch on all 15 mcbs, reset rcd then turn mcbs back on, more often than not switching. 3. And. 12. Mcb. Would result in rcd flipping again.

Is single rcd for whole house, but this has been decommissioned, and a small rcd has gone on to cu now. 3 and 12 are not affected by the rcd as they have been moved off. So

Cu
Contactum load should not exceed 100a so a single row 15 mcb and one rcd

Mcb never flip just the rcd.

We did have a flood up stairs about 6 months ago, and water did indeed come through light fittings, but all dry now? Should I replace? At the time aside from turning off for a while, nothing was done they never stopped working

How do you fix earth leakage. Is it a case of tighten screws or replacing appliance / socket?..


Electrician, back January, moving 3 and 12 was temp fix. Allowed by regulations under sparks discretion.

[The Builder]

Ok feverman ............. he's coming back soon, that's good. I guess the next step would be to maybe use a clamp meter to measure any earth leakage current. That would be a good start. Perhaps identify any high readings, and possibly fit that circuit with its own RCD or RCBO.
It shouldn't be hard for him to narrow it down, and he should have his own methods of dealing with it.

As far as anything you could do yourself with fault-finding........ you could replace 3 and 12's MCB with an RCBO (about £25 each though.) At least when they trip, the rest should stay on (not always though)

[BRIGHT SPARK]

Ill take that as a no then!

[fever28]

yes you are correct no certificate,

[fever28]

Progress, water and ellements get mentioned a lot,
We have two water cylinders, as a through back to when house was two flats a bout a year ago I replaced one of the cylinders and Emerson heater as lime scale had practically filled it. Of course the other one of equal age would very likey have same condition, unwired it on Monday night, and not had an rcd trip since. May be load , but hopefully it is the main fault. Fingers crossed,