See I told you there is no such thing as Safe Isolation. No one has mentioned borrowed neutrals?

So I was taught, and teach, when testing rubber soled shoes, no metal jewelry (tape if unable to remove for religious or sentimental reasons), don't lean on anything, one hand in your pocket and don't touch the shiny stuff! And remember there are bold engineers and old engineers but very few old bold engineers! 

My 2 pole voltage tester issued to me in the Post Office was a Drummond Test lamp known as a tester 133A. Standard issue until an engineer used it on a lift and managed to pull in a relay causing a contractor to energize and the lift to move causing a near miss accident.  Testers withdrawn and ordered to be destroyed and a a Martindale issued as a replacement.

The years roll on and I leave the Post Office. Later an engineer had a 2 pole tester hanging around his neck working on an isolated machine leaning inside the machine  manged by some fluke to short a power factor capacitor, with a broken blead resistor, and discharge the capacitor in to the centre of his chest causing him to convulse and wet himself. Big inquiry and back comes the Drummond Tester to be used to discharge capacitors

So would your safe isolation procedure would have picked up the charged capacitor waiting to bite you?

As Inspector Clusoe said, "always expect the unexpected".

JP

John Peckham said:

No one has mentioned borrowed neutrals?

or broken ones upstream of  the circuit we're working on ... and I'm not talking about PEN either ! It's not always a requirement of BS 7671 to isolate the Neutral, BUT that doesn't mean it's always safe to touch, just like the GNYE conductors out there !

John Peckham said:

No one has mentioned borrowed neutrals?

or broken ones upstream of  the circuit we're working on ... and I'm not talking about PEN either ! It's not always a requirement of BS 7671 to isolate the Neutral, BUT that doesn't mean it's always safe to touch, just like the GNYE conductors out there !