Any thoughts on this old thing?

[timhoward]

Quite old main switch RCD, it occasionally trips (every day or two), then won't turn on until all breakers are off.
Ramp test at time of testing was 25ma, earth leakage meter said 5ma (so consistent).
Is the RCD likely to simply be old?! Are they tetchy switching on under load?

Haven't got into IR testing yet. Their initial enquiry was for a CU change so a DP RCBO board will likely solve all issues or worst case show up anything that has intermittent faults.

 

[westward10]

I'm always happy to learn new tricks. What do others do? Mark cable sheaths where visible? Cable marker clips? Trust you keep them in same order?
My old gaffer used to put nicks in the cables which I never liked!

The number of times I find one leg of a ring swapped with an immersion heater has left with me no qualms about leaving future electricians clues! But I'm open to better ways.

Three rings, cut the ends off one, leave one as it was and strip longer ends on the other.

 

[timhoward]

Three rings, cut the ends off one, leave one as it was and strip longer ends on the other.

Simple and rather obvious now! And fold over the end on the immersion...you've got me thinking how many patterns this approach could make....

 

[ipf]

Fairly common practice with lighting as nicks won't fall or wear off, but never seen anyone nick cables that are ready to terminate.

Always a first, it seems.....YUK!

 

[nicebutdim]

Always a first, it seems.....YUK!

View attachment 109743

Have to agree that's rough.

 

[ipf]

Have to agree that's rough.

What do you mean....still one phase to connect....

 

[timhoward]

Not familiar with that old incomer and didn't want to assume busbar connection to it, but lettering appeared to show 'L' above left terminal.

I had a look this morning. I have to say, MEM made it about as idiot proof as possible!

Even told us how to put wires in it!

 

[nicebutdim]

I had a look this morning. I have to say, MEM made it about as idiot proof as possible!

View attachment 109747
Even told us how to put wires in it!
View attachment 109748

Seems as though only the top right of 'N' could be seen in your image in post #10, which made me wonder how the main switch was configured.

 

[GBDamo]

I'm always happy to learn new tricks. What do others do? Mark cable sheaths where visible? Cable marker clips? Trust you keep them in same order?
My old gaffer used to put nicks in the cables which I never liked!

The number of times I find one leg of a ring swapped with an immersion heater has left with me no qualms about leaving future electricians clues! But I'm open to better ways.

If all the rings tested out before the board swap then it's just a case of a quick continuity test to put the rings back together. No sharpies or flags required.

They're tests you have to do anyway.

 

[Mark42]

View attachment 109727

(Let's see if a conscious decision I took attracts anyone's attention!)

Not sure about that 3 - 1- 2 on the RFCs
What's that all about?

 

[timhoward]

Not sure about that 3 - 1- 2 on the RFCs
What's that all about?

The marks were put on before I dismantled the old board, before I proved end to end continuity and before I proved there were no inter-connections. I do this if it’s a shared RCD or no RCD as a record of how it was installed.
Just a little insurance policy really.

I’ve had a house once where some highly creative smoke alarm wiring was linking most circuits together. Live from light switch, N from nearest socket etc, and the immersion and the kitchen ring were also involved as well as a link back to a lighting circuit at the CU.
After that rather horrendous diagnostic experience I tend to mark the original position of the 2.5’s.

 

[Mike Johnson]

For cable labelling I use this: Brother PT-E550WVP Electrician Labelling Kit | Brother (PT-E550WSP) - https://www.tlc-direct.co.uk/Products/BRPTE550WVP.html? with a heat shrink tube cassette.