jim_in_sussex wrote:

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.

One might argue that the MCBs purpose is to protect the installation
from overload, not to prevent electrocution. That is what the RCD (if
fitted) is for.

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.

Had adequate RCD protection been in place then this would probably not
have not ended in a fatality though.

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.

Can work both ways I guess. Typically there is no requirement for
supplementary bonding on a kitchen anyway, and there are pretty strong
arguments for earthing appliances in these circumstances. A faulty earth
on an appliance could also result in a severe shock hazard when combined
with other faults.

--
Cheers,

John.

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