Strange power Trip

[333rocky333]

looks like a crabtree starbreaker, not sure you can still get them and if so likely expensive.
however the fault could be on any of the 5 circuits connected to it
or
the unit is faulty as DS suggested.

A ramp test basically increases the ma testing until it gives the level the unit trips, which should be within the units specification.
if it trips at a fairly lower level then it suggests a possible faulty unit.
To be honest id suspect a fault on one of the 5 circuits or something connected to them.
To trace your fault is not easy and sometimes sorts out Good electricians from basic electricians, its down to ones experience in fault finding and can be time consuming.

 

[Taylortwocities]

So its been OK since the summer, but its tripping now the weather is colder/damper?

I would suspect central heating/boiler or outside sockets, lights, etc.

Had a problem like this for a customer, I found a bollard lamp in the garden and the ants had built a lovely nest inside that covered the connection point.
When the ground got damp, the moisture wicked up the ants nest and pop went the RCD.

 

[securespark]

if it trips at a fairly lower level then it suggests a possible faulty unit.

Though, as you say, it could be a faulty circuit or appliance.

I went to a job in Staffs where the half times test failed constantly along with the ramp test. It turned out to be a dodgy fridge.

 

[JohnW2]

I went to a job in Staffs where the half times test failed constantly along with the ramp test. It turned out to be a dodgy fridge.

Presumably that would be a dodgy fridge and a dodgy RCD?

Kind Regards, John

 

[Iggifer]

Presumably that would be a dodgy fridge and a dodgy RCD?

Not necessarily, you're supposed to RCD test with all loads disconnected. I too have seen, in this case an RCBO and a remote drinks system fail on 5x, disconnect the load and it passes.

 

[JohnW2]

Not necessarily, you're supposed to RCD test with all loads disconnected.

Indeed - and maybe I was being too generous in assuming that is what secure had done

I too have seen, in this case an RCBO and a remote drinks system fail on 5x, disconnect the load and it passes.

Yes, although I've never experienced that myself, I've heard a good few stories like that, so it obviously does happen. More difficult (at least for me) is trying to think of a mechanism whereby it can/does happen. The other way around (RCD/RCBO becoming more 'trigger happy' with {possibly 'leaky'} loads connected) is a lot easier to understand!

Kind Regards, John

 

[securespark]

Yeah, a couple of sparks had been to this install and failed it, saying it needed a board change (the old MK sentry RCD was obsolete).

When I disconnected the outgoing neutral, switched off all the breakers and tested the RCD in isolation, it was absolutely fine.

I then disconnected all appliances & lamps from the circuitry and meggered through: all OK.

The fridge was (for the first time in my life) the first appliance I PAT tested (it was nearest the board) and it had a variable IR.

 

[JohnW2]

Yeah, a couple of sparks had been to this install and failed it, saying it needed a board change (the old MK sentry RCD was obsolete). When I disconnected the outgoing neutral, switched off all the breakers and tested the RCD in isolation, it was absolutely fine.

Ah - thanks for clarifying!

Kind Regards, John

 

[securespark]

No worries!

 

[nellymcl]

Update. Electrician still hasn't got back to me so I will need to try someone else.
No trips at the weekend, then Monday at 4pm it tripped. No one home. Then today around 3.15pm tripped again. This is really annoying now. So the 5 protected circuits are upstairs sockets, downstairs sockets, cooker, kitchen sockets and I think the last is the shower. This was added later so may not be on the protected circuits.

 

[nellymcl]

So the electrician has been and the concesus is that it is my caravan that has the reading 10 ohms between live and earth? (Might have picked that up wrong). This is plugged into a garage socket which is on my downstairs sockets protected circuit. Caravan now unplugged and we will see if thats us sorted.

Thanks for all your input.

 

[333rocky333]

More likely Neutral and earth, but we get the jist.
Hope its sorted

Did he not pinpoint it better than just condemning the van.
Is things plugged in within it.

 

[stillp]

the last is the shower. This was added later so may not be on the protected circuits.

It certainly should be!

 

[SimonH2]

... neither do domestic phone lines have metallic armour.

Not true, they do use SWA phone cable - typically for buried or "self burying" applications.

 

[bernardgreen]

Not true, they do use SWA phone cable

CW1198 I accept, but unlikely that a domestic telephone line will be present at the NTE as an armoured cable.