Residual current devices (RCD)
An RCD is a switching device that trips a circuit under certain
conditions, and disconnects the electricity supply.
If your electrical installation includes one or more RCDs, test them
regularly. You can do this by following the instruction label, which
should be near the RCD. The label should read as follows:
‘This installation, or part of it, is protected by a device which
automatically switches off the supply if an earth fault develops.
Test quarterly (every three months) by pressing the button marked
‘T’ or ‘Test’.’
The device should switch off the supply. You
should then switch it back on to restore the
supply. If the device does not switch off the
supply when you press the button, contact an
Testing the button every three months is
important. However, do not hold the test
button for a long period if the device does
not trip. If the RCD does not switch off the
supply when you press the test button, getadvice from a registered electrician.