What are these MCB's doing in my CU??

HappyHippyDad · May 17, 2012

Hello all,

I decided to have a look inside my CU to see if I could work out which MCB was supplying what. I thought it would be fairly straight forward but its not! :rolleyes4:

My aim is to fit a new up to date CU when I complete my Domestic Installers course as I want to practise for a while until I feel confident and competent in others' houses.

I have worked out the shower/cooker/lights and Ring main but there are 2 MCB's left which do not seem to be doing anything:

1. 15A MCB with a 2.5mm cable (I had an immersion heater removed when gas central heating went in, perhaps this is what it is? I also had night storage heaters removed)

2. 5A MCB with 1mm cable which appears to be doing nothing

3. Also there are 3 wires going into the 30A MCB which feeds the Ring Main, what could the third wire be?

Thanks guys...

Dave 85 · May 20, 2012

Christ! I wouldn't go pulling your house apart to remove every inch of a rendundant bit of 1mm, (lifting carpets, floorboards, chasing walls....) are you effing serious??? Just discon it from the C/U and cut it off. How the hell do you guys make a living working like this? Scrap price for 10 meters of 1mm T&E isn't that good surely?

For the record, if Im doing a rewire and the boards are up anyway, then yes, I do remove old cable where practical, but I wouldn't spend more than an hour or 2 on it even on a 5k job

Adam W · May 20, 2012

Dave 85 said:
Christ! I wouldn't go pulling your house apart to remove every inch of a rendundant bit of 1mm, (lifting carpets, floorboards, chasing walls....) are you effing serious??? Just discon it from the C/U and cut it off. How the hell do you guys make a living working like this? Scrap price for 10 meters of 1mm T&E isn't that good surely?

For the record, if Im doing a rewire and the boards are up anyway, then yes, I do remove old cable where practical, but I wouldn't spend more than an hour or 2 on it even on a 5k job

Nobody suggested that.
Have you been at the sherry?