"Pet" wrote in message
...

[...] should one be unfortunate enough to touch a bonded item
(sink/tap etc) and a live source, surely the resulting electrocution
would be far more severe than an un-bonded house?

The shock might or might not be more severe (depending on, for example,
whether your water service pipe is plastic or metal). Talking about the
severity of electrocution though is a little pointless: dead is dead.

I know theoretically you shouldn't be able to reach any electrical
source while touching bonded "bits" but that's never going to happen,

That's irrelevant. Earthing and equipotential bonding are measures to
prevent electric shock from 'indirect contact' - i.e. contact with accesible
parts which have become live as the result of a fault. Protection against
shock from 'direct contact' relies on other measures - principally
insulation! The wiring regulations (BS 7671) recognise the use of residual
current devices (RCD, RCCB, RCBO) as a _supplementary_ measure against
direct contact. That's why RCD protection is required for socket-outlets
likely to be used to supply portable equipment outdoors.

so is bonding MORE of a health risk than getting a little tingle
from an un-bonded house?

Protection against shock from indirect contact by 'non-conducting location'
is recognised in BS 7671, but not for domestic situations where it would be
completely impractical to implement.

After all, you're more likely to get a shock from exposed electrical
appliances than you are from a wire somehow connecting with the
copper pipes etc?

The EEBADS measure (earthed equipotential bonding and automatic
disconnection of supply) is there to ensure that the 'touch voltage' between
accessible metal items, be they electrical or not, is constrained to a safe
combination of voltage and time. Bonding ensures that the same earth
reference point is used for both the earthed electrical items
('exposed-conductive-parts') and non-electrical metalwork
('extraneous-conductive-parts'). Without bonding, the touch voltage could
be higher, especially with PME supplies.

Just a point for discussion rather than a "thats the law" kind
of reply.

It's not the law yet, but a public electricity supplier can refuse to
connect you if your wiring does not comply with the 'British standard
requirements - i.e. BS 7671. So thou shall't bond.

For further (fairly technical) background on why the wiring regulations are
as they are I recommend Paul Cook's Commentary - see
http://www.amazon.co.uk/exec/obidos/ASIN/0852962371/ (and note the updates
published at http://www.iee.org/Publish/WireRegs/updates.cfm).

HTH
--
Andy