RCBO keeps tripping - without explanation

[Badged01]

What sort of spark were you?

Clearly industrial ..... not used to this earthy stuff on domestics!

 

[plugsandsparks]

plugsandsparks

crystal ball time

Was thinking of compiling a list of all possible faults that could cause this but decided against it as it would take much typing and just listed one. Thinking about it a bit more and having spoken with Yoda he says "Most troubling it is, microwave is best removed for continued happiness"

 

[sonobit]

Heres one how about the hoover IS faulty and another bit of equipment and the other rcbos are not functioning correctly ive came across quite a few rcbos that dont work properly and have been sent back to MF.

 

[trev]

Bloody amateurs! It's obviously a fault on the kettle, everyone puts the kettle on to boil while they're doing a bit of vacuuming and no one ever suspects their good friend the kettle because it never lets them down.
Well, think again because it's no friend. It's there in the corner just waiting to scald you and one day it'll take its' chance.
Don't say I didn't warn you!

 

[GLENNSPARK]

What sort of spark were you?

one of these maybe:

 

[Benjamiin]

faulty rcbo I reckon! no appliance consistently trips the rcbo and dont trip other rcbos! disconnect the circuit and turn on rcbo and see if it still trips!!

 

[sonobit]

I find more rcbos FAILING to trip than faulty tripping without cause, purely due to the way they are made.

 

[Octopus]

faulty rcbo I reckon! no appliance consistently trips the rcbo and dont trip other rcbos! disconnect the circuit and turn on rcbo and see if it still trips!!

I've encountered exactly this before. Turned out in the end to be damp in a light fitting!

 

[pads]

To those who are saying 'faulty appliance'. It was initially thought to be vacuum, but as I said later --

I have unplugged or switched off (where via switched spur outlet - DP) all items on the same RCBO. And the RCBO stays on for about 2 mins or little more then trips. Without doing anything. (Yes even the boiler and kettle are off)

So its not the kettle or the vac.

I'll do some more testing in the morning.

Peter

 

[ferg]

Personally I don't think you deserved some of the responses you got.

If you've been out of the game for a few years you probably don't have your fault finding head on.

You have to bear in mind that a lot of new posters on here are DIY or chancers and there are a lot of folks sick of it.

As has been said before if you are still struggling with it after testing post up what tests and results and then you will most likely get some helpful responses.

There will probably still be some sarcy remarks but that is the nature of this forum.

 

[Engineer54]

Have you tried switching/swapping the upstairs sockets RCBO for the downstairs sockets RCBO?? RCD devices as a whole, are not known for being overly reliable. So if after conducting any further testing without results, try swapping over the two RCBO's....

 

[NickD]

Have you bought Nature® branded RCBOs? Everyone knows that Nature® abhors a vacuum.

 

[telectrix]

ramp test the RCBO with circuits connected but loads unplugged. note reading. then disconnect circuit/s from RCBO and ramp again.

 

[pads]

OK some observations and test results.
Observations -
during the evening last night the RCBO kept tripping with nothing plugged in (or DP off)
but during the night, I put the boiler on and wife put the dishwasher on - but the RCBO stayed on all night!!!

Tests
1 - the ring is complete (both L & N) - zero ohms.
2 - neither L nor N connect to any other circuit on the CU
3 - L-E, and N-E, and L-N all measure 38M for the ring.
4 - connected L&N across all the CU and they measure 34M between LN-E.

The max age of the wiring in the house is about 28 years

 

[Geordie Spark]

Have you tried switching/swapping the upstairs sockets RCBO for the downstairs sockets RCBO?? RCD devices as a whole, are not known for being overly reliable. So if after conducting any further testing without results, try swapping over the two RCBO's....

I find a nail to be a good substitute for an RCBO that keeps tripping.

You may have to cut it and bend it a bit to make it fit, but fit it will - with a bit of persuasion from a lump hammer.

 

[NickD]

OK some observations and test results.

Measured trip times for the RCBO?

If you don't have the wherewithal to test that, swap the RCBO with another RCBO on the board and see if the problem follows the RCBO to the new circuit (=problem is RCBO) or stays with the circuit (=problem is circuit).

 

[Octopus]

OK some observations and test results.
Observations -
during the evening last night the RCBO kept tripping with nothing plugged in (or DP off)
but during the night, I put the boiler on and wife put the dishwasher on - but the RCBO stayed on all night!!!

Tests
1 - the ring is complete (both L & N) - zero ohms.
2 - neither L nor N connect to any other circuit on the CU
3 - L-E, and N-E, and L-N all measure 38M for the ring.
4 - connected L&N across all the CU and they measure 34M between LN-E.

The max age of the wiring in the house is about 28 years

When was the rcbo board fitted?

 

[pads]

In reply to some questions -
a) RCBO fitted within last 3 months
b) My multi-meter has ranges from 20m >> zero ohms
c) My insulation tester goes up to 2000M

Further Testing Results
After the first set of tests, I discovered the burglar alarm was still plugged in !!
So re-tested and checked insulation for each circuit individually disconnecting from CU as tested.
Fuse--------Circuit--------------- LN------------NE------------LE
1 -----------Shower ----------- >2000 ------- >2000 ------ >2000
2 -----------1st Fl Light ------- >2000 -------- 134 --------->2000
3------------Gnd Light -------- >2000 -------- 149 --------->2000
4 -----------Base Light -------- >2000 ------- >2000 ------>2000
5 -----------1st Fl Ring --------- 1600 --------- 780 ----------1200
6 -----------Gnd Ring ------------ 390 ---------- 34 ----------- 420
7 -----------Base Ring ---------- 1170 ---------1100 -------- 1000
8 -----------Cooker ----------- >2000 ------- >2000 ------>2000
9 -----------Freezer ----------- >2000 ------- >2000 ------>2000
10 ----------Frid/Freezer ------ >2000 ------- >2000 ------>2000
.... All in M ohms
yes - I have swapped the RCBOs for gnd and 1st Floor - always gnd floor which trips.

The results above indicate the Gnd floor 'NE' is suspect - but cannot see anything. By the way all wiring is exposed in basement so didn't have to lift floor boards to visually inspect.

 

[telectrix]

agree that 34Meg. looks to be the likely culprit. i'd be looking in all accessories for a partially trapped cable or damp somewhere. with damp being favorite as the L-N and L-E are lower than other circuits.

 

[pads]

Thanks telectrix
By Accessories I assume you mean sockets and spur outlets, because all the appliances were disconnected during testing.

thanks