Not to complicate Adrian's thread.. here's an earthing funny that lay
dormant for many years.
Victorian house - Granny Flat extension added to the rear - all is well
till a graphic artist takes over the flat.
On arrival installs extensive computer system, and at end of day takes a
shower. Two minutes into showering, adjusts the controls a 2nd or 3rd
time - and gets a shock.

Shower is not an electric one, earth bonding is spot on, shower tray and
outlet are plastic. Whole electrical installation seems faultless -
very professionally done with separate CU in the flat on the end of long
armoured cable from main board in the house. [No RCDs anywhere]

The armoured cable is neatly terminated in a proper gland at the
original board.... into a box which is not earthed. So no earth
connection to the armour, the earth conductor out to the flat.

The filters in the computer gear were all probably legal, but there was
a lot of it and enough capacitance to bring the floating earth up to
110V on an AVO.
When the water went out along the drain, presumably with its
conductivity raised by some expensive toiletry - one doesn't like to
enquire! - and reached actually soil-type earth via the cracks in the
Victorian drains.....

I can imagine the installation was tested with the earth clip to the new
box, as being the most accessible earth point: so however well-
intentioned the Govt's new Regulations are, I suspect they wouldn't have
made a haporth of difference in this case.
--
roger
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