Just a couple of quick questions, what size earthing cable needs to be
employed in earth bonding a new sink in the kitchen and a stainless steel
bath in the bathroom- the choices from TLC is 6491 x 6.0mm / 10.00 mm, 6491
x 25.0mm, 6491 x 35.0mm Green Yellow Earth wire. I figure it'll be either 6
or 10 mm wire but thought I'd better check!
Secondly whats the difference between EC14 and EC15 Earth clamps, both are
for the same size pipes?
A kitchen sink does not need to be earth bonded unless it has a metal waste
pipe in contact with the earth outside. However the incoming water service
should be bonded to the main earth terminal (in or near the consumer unit)
with a minimum of 10mm^2 cable (16mm^2 recommended) unless both the water
main and the plumbing installation are plastic.
In the bathroom bond between the bath and any metal water & heating pipes
and the circuit earths of any electrical equipment which is within the
defined zoned areas (zones 0 - 3). The wire size required is only 4mm^2 and
this does not need to be run back to the main earth terminal (this is local
supplementary bonding). If the water pipes to the bath are plastic then the
bath does not need to be included in the bondng scheme unless it is in
contact with metal parts of the building structure. Bear in mind the object
of the exercise, which is to ensure that any metal items that you might
touch simultaneously are electrically connected together. More details and
example diagrams can be found in the IEE on-site guide (ISBN 0 85296 987 2).
EC14 (brass) is for dry indoor use only; EC15 (phosphor bronze) is suitable
for indoor or outdoor use. Both of those accept wires between 2.5 and
10mm^2. If you need to do any main bonding you might need the EC16 which
will accept up to 2 x 16mm^2.
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