Faulty MCB. Problem isolating ring final circuit at CU with MCB

[maxeon]

I am planning to move a socket outlet. The CU is largely unlabelled so don't know which 32 MCB to switch off. There are 2 x 32a MCB. All other mcbs are for lights (6a) and a dedicated immersion (16a).
To isolate the circuit, I tried switching off the first of the two 32a mcb which isolated some of the sockets but not the one I need to move. So I switched the 2nd 32a mcb off too (so now all/both 32a MCBs off but some of sockets still live.
So I tested RCD and main switch which tripped all sockets other circuits off.
I am assuming there is no cross over of ring circuits and that the 2nd circuit is not picking up a live from elsewhere (heavens forbid) although I then switched off all MCBs on all circuits and the 2nd 32a circuit was still live.
Can I conclude that the 2nd MCB is faulty and so not switching off and needs replacing or is there any other possible cause?
I'm an amateur so please bear with me and this is my 1st post.

 

[westward10]

Best get an electrician in to be on the safe side.

 

[buzzlightyear]

it is possible the socket you are working on, is feed from one of the lighting circuits . and advise to get a local spark in.

 

[Pete999]

Looks to me like you could do with an Electrical Installation Condition Report (EICR) on your installation.

 

[LankyWill]

Sounds like your out of your depth, I'd advise you get a electrician to come and sort it. Might be a chance for you to watch him and gain some experience.

 

[Specialist]

As westward10 has said, your best solution is to call a qualified Electrician in. Get them to test the circuit & rectify the situation.

 

[buzzlightyear]

I'm an amateur so please bear with me

maxeon, are you a spark or a (DIYER)

 

[Specialist]

maxeon, are you a spark or a (DIYER)

As already stated, he's an amateur.

 

[Taylortwocities]

I'm an amateur

Do you have a two probe voltage tester.
First thing us to ensure that the MCBs are actually disconnecting when they are switched off.

Next you'll need to go done investigating yo find out which MCBs feed which sockets.
Put coloured stickers on the sockets so you don't get lost.

That should give you a starting point. If you can't cope with that simple stuff, then an electrician is what you need.

 

[telectrix]

as above excellent advice. you need an electrician with the appropriate tools/test gear/ knowledge to sort this. you could fit your extra socket by isolating the whole installation, but there sounds like there's a nasty lurking away somewhere and to be honest, you won't have a clue how to find and rectify it. it could turn out to be fatal.

 

[buzzlightyear]

Do you have a two probe voltage tester.

or a cat they say got nine lives, cos you only have one!

 

[westward10]

Buzz does make me smile however that may become tears if I worked with him

 

[telectrix]

yep. a cat has nine lives. he's OK till he comes across a 10 way CU.

 

[Lagentium]

Some replies look like they have been pasted from google translate!!

 

[buzzlightyear]

please keep at the back!

 

[Pete999]

please keep at the back!

Keep what?

 

[maxeon]

Do you have a two probe voltage tester.
First thing us to ensure that the MCBs are actually disconnecting when they are switched off.

Next you'll need to go done investigating yo find out which MCBs feed which sockets.
Put coloured stickers on the sockets so you don't get lost.

That should give you a starting point. If you can't cope with that simple stuff, then an electrician is what you need.

 

[telectrix]

please keep at the back!

pass the dutchie.

 

[Pete999]

pass the dutchie.

You reckon?

 

[maxeon]

I have a multimeter basic model but works ok. I am always very careful to check and double check that a circuit is actually isolated realising that RFCs can be cross linked by someone not paying attention to detail in there working practices. My double checking with instrement and a lamp before actually working on the circuit, lead me to find this problem. I appreciate I could simply flip the main switch and isolate the whole installation but I relaise that would not address the potentially serious problem. I suppose I was just wondering if a faulty MCB is the most likely cause bearing in mind I had switched off all other mcb including lighting/immersion circuits.
I had started to map out the mcbs to the outlets so as to get the CU properly labelled but then very quickly came across the issue. I think the next task is to check each/every MCB is actually switching off which may hopefully narrow down the problem.