Replace MCB

Postby jungle » Sat Oct 18, 2008 12:18 pm


I have a MCB (Protek 132 32A) that has trip, and the switch has broken to reset the MCB.

I therefore need to replace the MCB unit. I've ordered the part, and think that the correct process will be to turn off the main RCD incomer, then unscrew the main plate, unscrew the MCB, take out and replace with the new one in reverse order.

Do you know if this is correct - or have I missed any crucial steps? Also am I 'allowed' under electricial regs to do this.

many thanks,
Posts: 2
Joined: Sat Oct 18, 2008 12:14 pm


Simply Build It

Postby ericmark » Sat Oct 18, 2008 3:53 pm

I don't know of any regulation which states what experience and knowledge is required. 134.1.1 Good workmanship by competent persons or persons under their supervision and proper materials shall be used in the erection of the electrical installation. Electrical equipment shall be installed in accordance with the instructions provided by the manufacturer of the equipment. Since we are part of EEC one does not have to get British qualifications and even with British there are more people than just City & Guilds who set standards I know one local college set it's own exam for 16th Edition wiring regulations.
The only legal limit is Part P and although you can't change complete consumer unit you are allowed to replace like for like.
If all the covers have been installed to your consumer unit what you explain is likely correct but one can not guarantee the covers are in place and EAW act says you should isolate else where. But in most cases isolators are not provided between the fuse and consumer unit and only pulling the main fuse would isolate else where which you are not allowed to do.
As an electrician we know what to expect and we take prosecutions to ensure we don't get caught out even if the consumer unit has not been installed or maintained correctly but for me to tell anyone to go ahead and DIY when all we know is you can use the internet would be somewhat fool hardly.
So do you think you have enough training to avoid danger.

Postby jungle » Sun Oct 19, 2008 7:45 am

thanks for reply.

So in a nutshell, the danger will be that when the cover is off, the main feed is still live (can't be isolated) and therefore if I slip with the screwdriver, things could get interesting.

Maybe I'll get someone in.

Posts: 2
Joined: Sat Oct 18, 2008 12:14 pm

Postby ericmark » Sun Oct 19, 2008 1:36 pm

I think you have seen the problem. If all done correctly in first place no problem but until you take off the cover you will not know.

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