Replacing an MCB

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Aplologies if this has been done to death but I could use some advice before I blow myself up, or end up with another 240v shock (yes the good old christmas tree lights).

I live in what was a council house, now housing association. We had an electrician in to re-wire the shower unit. He put in a RCD and replaced a re-wire fuse with an MCB. Everything worked fine.

Then the place moved to a housing association and they did the usual rushed, substandard job (including very picturesque external conduit) and replaced the fusebox with a nice new crabtree CU.

The problem is that they put in a 32amp MCB in for the 9.8kw shower. They kept going on about the wiring being too small. Now the shower trips when on full power. In the warmer days I can turn to economy and it works 100%

The wiring is 6mm but is clipped and not going through any insulation, etc so as far as I can tell, it's on the limit but safe (as I said it was checked by a qualified electrician).

I am thinking of replacing the MCB. I am a novice when it comes to electrical but I can re-wire plugs, sockets, light switches... I do not know much about CU's
2Q's really

1. I need a 40amp mcb, I take it I should go crabtree, however I can't find any locally, any suggestions on source?

2. Apart from the obvious, turning off the power, what is the replacement process?

If it's complicated or dangerous I'll call the electrician but I'd rather DIY it.

Thanks for you help :D
 
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Crabtree starbreaker MCB's are widely available from any good wholesaler.
Use only Crabtree as others won't fit into the busbar (push fit)

9.8kW = 42.6amps
6mm cable clipped direct = 47amps
 
Thanks Qedelec, so I'm not going to blow myself up then :LOL:

Anyone know the rough fitting process?
 
Inform Building Control
Isolate, check you've isolated, check the instrument you have checked with.
Remove cover, identify the MCB, insert screwdriver in slot below breaker and press down, pulling forward as you do.
Undo screw at top of breaker, remove wire and insert into new breaker.
Tighten screw.
Hook breaker over DIN rail and press into busbar.
Check ALL connections.
Carry out R1+R2 test and insulation tests on cct.
Replace covers.
Restore power.
Perform Zs on cct.
Inform Building Control you have finnished and are ready for the work to be inspected.
 
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