Electrical Earth Leakage Protection
Electricity can be a hazard in the workplace. There is danger if a person comes in
contact with an exposed live conductor, arising from items such as a damaged power tool or
other equipment or a defective connecting lead or damaged extension cord.
Electricity is an invisible and silent danger. This can lead to injury or death,
because there is no safe way to detect the presence of electricity without using an
instrument for testing.
Residual Current Devices (RCD Safety Switches)
A residual current device (RCD) is a device that is capable of detecting a small amount
of electrical current, which, under fault conditions, could pass through the human body
and cause an electric shock. It is designed to detect this current and disconnect the
electricity supply in a very short period of time, about 30 milliseconds.
A residual current device does not ensure safety. It is designed
to disconnect the electricity supply when there is a leakage of electricity to ground, as
may occur during an electric shock. It is important to remember that if a person is
in contact with both the active and neutral conductors of an electricity supply, the RCD
may not operate and an electric shock would be received. This shock could kill.
Residual current devices can be installed on a switchboard or in a general purpose
outlet (power outlet). Portable types are also available that plug into socket outlets.
RCDs used in domestic and industrial application as designed to trip with an earth
leakage current of 30mA. RCDs used in hospitals and the like, are designed to trip
at 10mA.
Typical Installations
Electrical equipment such as listed below should be protected by RCDs.
