Bad Ideas - Electrical
Things to Avoid Doing!
Single whole house RCD
A single appliance earth fault, or assorted non-fault conditions, will cut your whole supply off. Not very good if you like lights and a working freezer, and don't have Sherlock Holmes on hand to figure out where in the system the problem lies.
Freezer sharing RCD with half the house wiring
Any RCD trip is liable to ruin your freezer contents. A common setup in new installations unfortunately.
Plugin electric heating
One of the most expensive heating methods of all.
Historic rubber wiring
Old rubber wiring is regularly very badly perished, leaving bare uninsulated wires intertwined in unsuitable places. High risk of fire and shock.
Disturbing historic rubber wiring
A quarter inch of movement is enough to cause a short where wiring is badly perished. Shorts cause shock and fire, or blow supply fuses. Historic rubber wire should normally be left alone until replacement, unless it can be verified that the insulation is still in one piece.
Fitting a mains drill with an RCD
...in the mistaken belief that this offers some protection if you drill into a live wire. It gives no such protection, but encourages less care to be taken over where one drills, thus increases the danger.
Showers wired on 2.5 mm^2 T&E
Cable used like this is a fire risk and does not last long. One exception is old 3kW showers which are ok on 2.5 T&E, if a dribble of lukewarm water can be considered ok.
Showers that give you a tingle or shock
There are normally several layers of protection against this occurring with showers, if a shower reaches this point the installation is in a terrible state and may fry you at any time. All users of such showers are automatically nominated for the prestigious Darwin Award.
Plastic waterpipe earth
Houses generally used to use the metal supply waterpipe as an earth, and a good earth it was. But today many water supplies have been replaced with plastic pipe, which may leave the house with no earth connection. This is a real shock hazard.
Local earth rod & no RCD or ELCB
May be found on some 1950s installs and older. Often results in no effective earth protection, as earth fault currents will neither blow a fuse nor be kept down to a safe voltage by the earth rod.