Rogue RCBO?

[k.fuery]

I have a Wylex board feeding six sockets, a fridge freezer and a microwave off a 32amp RCBO on a ring circuit in my kitchen. This has worked satisfactorily for 3 years, with the fridge on 24/7, using the microwave and boiling a kettle. Never using all sockets at once, but now, the RCBO trips when using any single socket. If I use a kettle, it will trip half way or more into boiling, i.e it doesn't trip at start up. Kettle was replaced and still tripped. Same with the toaster. Microwave and fridge freezer working OK and during the day, I boiled the kettle 3 or 4 times, no problem, then tonight it tripped again, half way through its duty cycle. All wiring to back of sockets is clean, undamaged and firmly in place.
Could the RCBO be at fault, or could there be other reasons?

 

[Andy™]

could be a faulty RCBO or could be a wiring fault. would need proper test equipment to determine the cause

 

[SPECIAL LOCATION]

The RCBO could be operating perfectly correctly and doing its job detecting a very small earth leakage current.

RCBO's combine both an MCB function and an RCD function.
The 32A value you mention is the MCB overload current value.. It is unlikely to be this element causing the tripping issue.
The RCD function should be 30mA rated.. I think on Wylex devices this is typically written on the front of the RCBO just below the B32A MCB rating.
(Some manufactures write it as 0.03A)

Some appliances can exhibit natural earth leakage during normal use..
combinations of failing appliances, natural leakage, and or deteriorating cable or joints can cause intermittent or apparently random tripping of RCBO's

RCBO's can become oversensitive, (They must NOT trip below 15mA, but the MUST trip at 30mA or greater)
An industry standard RCBO tester can verify the operating characteristics to confirm if the RCBO is faulty or not.

Cables should be tested for continuity of conductors, and insulation resistance between conductors and earth,
again with an approved test meter..

These RCD & cable test values can be compared against values written on the electrical certificate issued when the RCBO was installed 3 years ago..
If the test readings are near identical, then that would suggest your problem is appliance related.

From past experience of faulty RCD's and/or RCBO's over my years of self employment since Feb 1999,
The most common failures tend to be not operating fast enough or not operating at all..
compared to oversensitive RCD/RCBO, which tend to be far less common.

DO NOT try replacing the RCBO unless you have had it tested first to confirm it is faulty.

 

[k.fuery]

The RCBO could be operating perfectly correctly and doing its job detecting a very small earth leakage current.

RCBO's combine both an MCB function and an RCD function.
The 32A value you mention is the MCB overload current value.. It is unlikely to be this element causing the tripping issue.
The RCD function should be 30mA rated.. I think on Wylex devices this is typically written on the front of the RCBO just below the B32A MCB rating.
(Some manufactures write it as 0.03A)

Some appliances can exhibit natural earth leakage during normal use..
combinations of failing appliances, natural leakage, and or deteriorating cable or joints can cause intermittent or apparently random tripping of RCBO's

RCBO's can become oversensitive, (They must NOT trip below 15mA, but the MUST trip at 30mA or greater)
An industry standard RCBO tester can verify the operating characteristics to confirm if the RCBO is faulty or not.

Cables should be tested for continuity of conductors, and insulation resistance between conductors and earth,
again with an approved test meter..

These RCD & cable test values can be compared against values written on the electrical certificate issued when the RCBO was installed 3 years ago..
If the test readings are near identical, then that would suggest your problem is appliance related.

From past experience of faulty RCD's and/or RCBO's over my years of self employment since Feb 1999,
The most common failures tend to be not operating fast enough or not operating at all..
compared to oversensitive RCD/RCBO, which tend to be far less common.

DO NOT try replacing the RCBO unless you have had it tested first to confirm it is faulty.

Thank you for taking the time to write such a comprehensive reply. My frustration arises due to the nature of the fault. Last night, as an example, the air fryer, (double insulated, could that point somewhere?) ran fine, but with the kettle on its own it tripped. This morning, the kettle and the dishwasher and the washing machine all ran fine.
Looks like I need a sparks, just wary because last time I got hit with £65 for a double pole main switch connector, + labour.
I take your point about replacing RCBO. @£30 a pop.

 

[Murdoch]

Looks like I need a sparks, just wary because last time I got hit with £65 for a double pole main switch connector, + labour.

£65 for a DP switch - was it gold plated?

No spark can give you a fixed price for a fix like you describe - it could take 1 hour or 4 hours plus parts ...........

 

[UNG]

During an EICR recently I found no continuity on the downstairs ring, eventually tracked the fault to a cable that had been spiked by a picture hook pin which must have happened many years ago as the plaster didn't have a pinhole in it but the conduit below the surface clearly did. After removing the damaged cable it was clear that the insulation on the live conductor had been pierced by the pin and had also been in contact with the earth as internally the cable was showing signs of the start of a fire with the blackened live and earth, though the IR tests didn't give any readings low enough to cause concern
The installation was a 3036 Wylex with and upfront RCD and I suspect that the RCD may have operated and been reset a few times until such time as the fault blew clear and normalish operation resumed in blissful ignorance of the problem below the surface for possibly around 10 years
Installation now has a new 10 way RCBO fusebox consumer unit and a repaired ring circuit

 

[binky]

can't think of any DP switch at that price, unless it's some fancy designer stuff with glass front plates that can be wall-papered to match the decor.