what is an rcd

We asked about electrical safety, specifically rcd's Allow me to explain.

RCD stands for Residual Current Device, also know as an Earth Leakage Circuit Breaker

Normally electricity flows (current) down one wire (Live) and through a device (say a pump) to make it operate and back again down a second wire* (Neutral) the Third wire you will find in a cable is the earth. Its purpose is is to connect the casing of a device to earth, the theory being that if the live wire touches it, the fuse blows breaking the circuit.

But the problem is as most pumps have plastic casings. which does NOT conduct electricity if the Live wire becomes detached / damaged it has no where to go. So when the pump or water which it is in is touched it is now LIVE and so the electricity flows through who ever touched it, to earth at the least giving a very nasty shock, but more than likely KILLING who ever touched it.

In normal operation as previously stated electricity flows in one side and back down the other, there by being "balanced" if however it detects an "Imbalance" say the device (pump in this case) has a damaged cable and it is touched the electricity will flow to earth via who ever touched it. The RCD will detect this and switch off the current instantly saving your life. That is why you should always use an rcd.

A few points.

Always make sure that ANYTHING electrical you use has a secure but not damaged cable.

If you find a damaged cable on an appliance, get the cable changed DO NOT USE IT.

If it is a submersible pump throw the pump away DO NOT attempt to repair it. A pump may cost several pounds and can be replaced, A life is priceless and can not be replaced.

If you are not sure consult a qualified electrician.

*This the generally accepted flow of electricity but in reality it is reversed.