Richard Conway wrote:

John Rumm wrote:
Richard Conway wrote:

On Friday I will be fitting a new bath which for reasons unrelated to
this thread (well, not entirely I suppose) will be made of steel.

Our bathroom currently has no equipotential bonding, and I am aware
that in order to comply with the regs I will either need to install
equipotential bonding or upgrade my installation to meet the 17th
edition regs.

A new metal bath in unlikely to make the situation worse...

At the moment, my CU is a split load that consists of the following
(please bear in mind it's a small terraced house):

RCD Side
Whole house sockets (ring)
Kitchen Sockets (ring)
Oven (radial)
Immersion Heater (radial)

Non-RCD side
Upstairs lighting (including bathroom fan)
Downstairs lighting

Now, I understand the dangers of putting either of the lighting
circuits on the RCD side, but what if I replced them with RCBOs?
Would this be enough to not require equipotential bonding as there
would be no circuits in the house without RCD protection.

As long as you main equipotential bonding is up to scratch then you
could replace the lighting MCB with a 30mA/6A trip RCBO. (I am
presuming the downstairs lighting circuit does not enter the bathroom).


The downstairs lighting circuit does not enter the bathroom, but it does
travel in proximity to the pipework in some places, which I thought was
one of the reasons behind equipotential bonding in the bathroom - i.e.
to prevent a large potential difference occuring if, say, a tap were to
become live as a result of it's supplying pipework coming into contact
with a faulty cable etc.

The bonding is intended to limit the potential difference you can
experience as a result of conductive components introducing dangerous
voltages into the zone. Normally one would only include the CPCs of a
circuit that actually enters the bathroom within the bonding.

However, if you think the layout of the pipework/wiring is such that
there would be a real possibility of the pipework making contact with
the downstairs lighting circuit, then you would be better off installing
supplementary bonding in the bathroom. (in reality the main bonding
would hopefully ensure that the existing MCB on the downstairs lighting
circuit would open should such a fault occur)


--
Cheers,

John.

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