Stefek Zaba wrote in message ...
Tim (Remove NOSPAM. wrote:

What if incoming water pipe is plastic? (no oil or gas) The Earth rod is
then sufficient??

No - if all or most of the house pipework is in copper (or other metal,
naturally),

snip

I have difficulty with the standard answers to the question of bonding
in a kitchen

(a) a big enough current will flow to make any fuse/MCB pop
nice and quickly,

hopefully yes, but a fuse/mcb won't trip on the current/voltage that
gives a fatal shock - you need an RCD - even then that takes 0.4s - or
40 half cycles each reaching a peak 340volts.

(b) even while the fuse/MCB is deciding how quickly to
pop, the pipework doesn't rise to a voltage far above earth (cos the low
resistance of its connection to earth means most of the 240V is dropped
on the L side of the fault).

Something like that was the subject of the recent inquest. The metal
shelf went to 240v & the earthed casing of the (?)dishwasher stayed
resolutely at zero volts.


I wonder whether over-earthing/bonding in a kitchen can compromise
safety: perhaps more regard should be paid to the merits of relying on
natural protection from clothes, shoes etc & minimising exposed metal
surfaces in a kitchen.