On Sat, 13 Mar 2010 22:19:02 GMT, Harry Bloomfield
wrote:

If the wiring dates back to the 1960's, it was not unusual for the
lighting circuits not to be provided with an earth. Later mods and
improvements to the circuits might mean metal boxes installed, but with
no earth.

I've seen early 60's wiring with metal backboxes for the light
switches and no earth, the wiring being double insulated either in
singles or zip connected doubles.

Makes things interesting when you contact a switchplate fixing screw
with a finger and the backbox has been made live from a missed stray
conductor (stranded not solid conductors)


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