RCD Random Tripping Issues

[Jazzhands]

Hi guys,

I am having issues with random RCD tripping that I can't isolate for the life of me.
It can be as random as tripping once a fortnight to 3-4 times a day. No time pattern, during the day, evening, middle of the night, when out of the house. Can be when very little load on (middle of the night) or when lots of appliances on.

I have a Hager CU with all the socket rings, garage, boiler running to MCBs which are protected as a group by an RCD.
Whatever is causing the problem is tripping the RCD which takes out all the above circuits - and cost me a small fortune in wasted frozen food!

In order to try and isolate to a circuit should I replace the MCBs with RCBOs and see which one trips then?
If I do that can I still keep the main RCD too or do I need to replace it?
Anything else you think I can try?

 

[AndyPRK]

You can’t keep the rcd as it will still trip as well as the rcbo. Post a pic of the cu

 

[EFLImpudence]

You could do that - then see which RCBOs. DON'T trip - and which one does along with the RCCB.

 

[Jazzhands]

Pics as follows. It's the RCD above "RCD Controlled Circuits" that keeps tripping.

IMG_20200805_154859

• Jazzhands
• 5 Aug 2020

IMG_20200805_154805

• Jazzhands
• 5 Aug 2020

 

[AndyPRK]

If you aren't using the garage/outhouse power ATM, I would open up the cu (turning the main sw off) and disconnect the neutral wire to it, and the live from the MCB and see if it stops tripping. Neutral must be disconnected.

I know you don't really want trial and error, but worth doing while you consider your options

 

[AndyPRK]

I would also order 2 B32 RCBO to be fitted on the other side of the board.

One for the kitchen sockets (I assume the freezer)
And one for downstairs sockets (or whatever you consider important)
or if the garage is the troublesome item put that on the RCBO

The alarm and smoke alarm can be combined to the same MCB to make room

 

[Jazzhands]

I would also order 2 B32 RCBO to be fitted on the other side of the board.

Assume the Hager ADA332G would do the job?

I should have said too - all the circuits/MCBs to the left of the RCD in the pic are protected by the main RCD.

 

[AndyPRK]

Sorry I’m not familiar with the Hagar part numbers. I see you have a ADN fitted already.
If they look the same it’s a good start

 

[Jazzhands]

Bloody thing's tripped twice tonight, hardly anything on! Very frustrating.

 

[Jazzhands]

So I'm going the whole hog and replacing all the RCD protected MCBs with RCBOs. I then need to remove the main RCD shown above "RCD Controlled Circuits" in the picture above. Can I just replace this RCD with a 100A Isolator Switch the same as the main Isolator?

 

[EFLImpudence]

Can I just replace this RCD with a 100A Isolator Switch the same as the main Isolator?

No need, the Main Switch already controls the circuits. (Well, it should).

 

[Jazzhands]

Unfortunately it's a split load CU so the bus bar doesn't go all the way across.

 

[EFLImpudence]

Then - buy a new long bus bar,

move the left one across so that they both meet in the last MCB, or

use the existing live conductor from Main Switch to RCCB to connect the RCBOs.

 

[EFLImpudence]

You will need an RCD tester to show that the new RCBOs work properly.

If you had one already, you would probably be able to find the fault.

 

[AndyPRK]

But you could use a main switch to get you going. Looks poor but would work