"People
have the illusion that just because the wires are the right way round which
is all a simple plug-in socket tester shows the earth must be good.Some testers will pass as OK an earth with a
resistance far too high to allow enough current to flow to blow a fuse,"
says Steve Dunning, MD of Martindale Electric.
His
warning comes after a report published by the Health & Safety Executive.
"Simple socket testers will not show when earth fault loop impedances are
excessive," he continues. "And
the situation isn´t helped by manufacturers making false or misleading claims
in their adverts and user instructions.
The only safe approach is to use the appropriate 16th edition
instruments, or a more advanced socket outlet tester that detects and displays
earth fault loop impedance levels, like the Martindale E-Ze Check™ Xtra."
"Simple plug-in socket testers are
in every electrician´s toolbox and have been around for many years, but they
are not suitable as the only method of checking whether a socket is safe. They may show that the socket is functional,
but that does not meet all the requirements of BS7671," he adds. "Users need to understand that no socket
tester can ever detect neutral earth reversal.
Our product states this explicitly." The E-Ze Check™ Xtra uses Martindale´s unique
T-Safe™ technology to carry out earth loop impedance testing without tripping
30mA RCDs, even sensitive electronic RCDs that would normally trip before an
earth loop impedance measurement can be made."
When
the market only offered simple socket testers, the desire to speed testing and
reduce costs by using a cheap, simple, socket tester was understandable, if not
excusable.Now that low-cost, non-trip,
earth loop impedance indicators are available for less than £50, there´s no
excuse for not validating the quality of the earth.
August 2007