Q: A colleague has stated that to prove socket-outlets work correctly all we need to do is to plug in a socket-outlet tester which lights up to show the earthing is satisfactory. This would save on expensive test equipment and time spent testing, is this correct?
A: The short answer is NO, these socket testers do not confirm the effectiveness of the earthing of the installation. There have been recorded instances where although these socket testers have indicated an earth is present the actual recorded value has exceeded the maximum permitted value for the earth loop impedance.
In this case the fuse or circuit breaker would not have operated within the timescale to prevent an electric shock.
Therefore these socket testers can easily mislead the user into believing a socket-outlet is safe when it is anything but safe.
There is no substitute for following the correct procedures in carrying out electrical testing of the installation. These socket testers when used in the appropriate circumstances can assist the electrical contractor but cannot replace the proprietary test instruments.