DIY Doctor

Is my self cert electrics compliant on new build?

Postby Leeg232 » Fri Apr 17, 2020 4:24 pm

I have moved into a new build and even though building control has been signed off I have concerns over the self cert wiring. I have been looking at the lighting circuit in the loft to add a light. I can see that the electrician has wired the the lighting circuit behind the light switch. So instead of the circuit going from rose to rose with a cable to the light switch. The circuit cables run to the light switch and connectors used to create a connection and a single cable back to the spotlight or rose. Is that Part P compliant. Also built in appliances like the dishwasher have no cut of switch when the plug is behind the unit. Can some give me an idea if I need to get this inspected formally so I can raise this with the builder? Thanks
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Postby stoneyboy » Fri Apr 17, 2020 9:22 pm

Hi leeg232,
Neither of the items you describe contravene the regs.
It is nice to have accessible means of isolation for all built in appliances but not mandatory.
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Postby ericmark » Sun Apr 19, 2020 10:16 am

I have the old style lighting for most of the house, so my electronic light switches have no neutral, and some bulbs (G9) do not like this, having a neutral at the switch is good today, the problem is volt drop, allowed 3% for lights, 1 mm² cable can have 29 meters at 6 amp, 1.5 mm² around 45 meters, there is a point that the design current does not have to be the MCB rating, so the designer could say even distributed so could double those lengths, but in the main that was why we try to reduce cable lengths where possible, and ceiling rose to ceiling rose reduces cable lengths. But nothing says how it should be done, and only in the UK or other countries who have adopted UK methods are lights wired that way.

With old washing machines there was a problem with the weights, if the weight is too thick it will not fit, but if too thin it will fit, and seems firm on assembly, but it is only the flashing making it seem firm, so in use the flashing would crumble and the weight would be loose, so the washing machine would smash anything near it, and you could not touch it to turn it off, but today washing machines have sensors which auto switch it off if out of balance, so the isolator is no longer required. Although still a good idea.

There are many points which can be debated with house wiring, I think the idea of just two RCD's is silly, I have 14, also putting laundry items in a kitchen, kitchens are for food, not dirty cloths, I have a utility room, and fixed items over 2 kW should have a dedicated supply, but common to have the washer/drier on the ring final, but BS7671 is not law, and Part P had to allow any of the European regulations to be used, so Part P would allow German sockets, but BS7671 does not allow them.

Seems daft I know, but I worked in one village which was for American service personal, and it had a split phase 240 volt supply so 120 volt to USA style sockets, Part P will allow this, BS7671 wiring regulations will not.
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