On Thu, 19 Jan 2006, wrote:

Do all fixed water appliances: boilers, cyinders with pumps on them and
the likes of, require a separate earth wire from the appliance back to
the meter earth terminal bar?

no

Or will a wire from an earth tag to the
switch be enough?

yes, unless in a bathroom or other location where equipotential
bonding is required

What if the appliance has mainly plastic piping
connected to it?

it still has to be earthed in accordance with the manufacturers'
instructions.

--
Alistair Riddell - BOFH
Microsoft - because god hates us