Home. Inspections. Regulations. Domestic. Industrial. Contacts. Ask me about automating your home

Part ‘P’ of the building regulations applies exclusively to domestic dwellings. Click on the ‘regulations’ link above for more details about what is and is not notifiable.

All work should also conform to the latest IET wiring regulations which are currently the 17th Edition 2008. There are other regulations applicable to domestic installations these include Part ‘B’ which states that there should be at least one mains powered smoke or heat alarm per floor and these should be linked so one detector will set the next off.

All these regulations are there to ensure your safety. It obviously makes sense to have RCD protection, protective conductors, cables run in safe areas and rated correctly to the load and protective device. If you were selecting a new car you would probably check it’s Ncap rating, how it survives a crash. Well you should take the same care when selecting an electrical contractor. Is my installation going to be safe and if I do something silly like stick a knife in the toaster to get the stuck bread out, will I get a shock? You may think it will not happen to you, well my son did the toaster thing and because we had an RCD he is still here to tell the tale!

Residual Current Devices come in many flavours but basically all do the same job. They detect electricity leakages, they do this by comparing what travels out through the live wire to what comes back through the neutral wire. They have a rating, 30mA is the most common. If they detect a 30milliAmp difference in what is going out to what is coming back they trip. Now it just so happens that 30mA is deemed as a ‘safe’ amount of electricity to flow through the body for 0.4 of a second. So RCD’s have to trip in that time or less. When one is installed it should be tested to ensure this is so. The test button provided on the device does not do this! It just checks that the mechanics of the switch are working correctly. The time and trip current has to be tested with a special meter.

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Over the years I have seen some domestic installations that could have quite literally killed someone. These have usually been done by the householder or a ‘mate’ who knows a bit, but not always.
Some examples of which would include wall lights wired in bell wire and supplied from the rooms ring main which is protected by a 30A fuse. If a fault occurred with the light the wire would disintegrate before the fuse would blow.
I have tested metal fittings that seemingly are connected to earth and found they are not. Further investigation showed that not only had the supplying cable been drilled through twice, once severing the earth or CPC wire. Another screw was only insulated from the live cable by the rawl plug!
Cables run under the carpet are another common find, very dangerous when they cross or run along the carpet gripper!
On two occasions entire houses not connected to earth due to a fault with the suppliers earth connection.
My personal favourite though is a standard internal 13A 2 gang socket screwed to the outside of a house to use with the lawnmower, no RCD, no weatherproofing, lethal!