Kitchen sink equipotential bonding

[robgraham]

I've spent the morning replacing the kitchen mixer tap.

I had to disconnect the bonding wiring to get at everything. If the house wiring is covered with an RCD and the lighting with RCBO's, do I need to reconnect this rat's nest?

Thanks Rob

[Toby]

Equipotential bonding (As in just connecting the pipes together) is not required in the Kitchen, however, you do need to connect the main water pipe (assuming it is metal) to the earth terminal of your consumer unit (either inside the CU or via a block between it and your main cutout/earth spike)

[John Rumm]

A kitchen is not a room where supplementary EQ bonding is actually required, and a sink in itself is not capable of introducing a potential into the room even if it were. So the sink itself does not need bonding, and neither do the taps. However it is not uncommon for the main bonding conductor to be somewhere in the vicinity since that is often where the cold main comes into the house - so make sure you have not disconnected that. If the boiler is in the kitchen, you may also have a link to the CH pipework. This does count as extraneous conductive metalwork, that should be connected to the Main Earth terminal as well, and since the boiler is a place all the pipes converge, this is typical location.

[robgraham]

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Thanks guys - blue plastic mains pipe and no CH boiler in the kitchen (oil and it hangs on the wall round the back of the house - no...no.. no... not the kitchen!)

So that's a quick snip then - good.

Rob

[BartC]

I stayed in a studio apartment on holiday once (somewhere in the caribbean).

When you filled the aluminium sink and put your hands in, you felt an unpleasant electric shock.

Same with grasping a metal-handled pan from the table-top electric hob unit.

This place also had a shower-head over the bath, with the heater device attached directly to the shower-head (with a trailing cable to an outlet on the bathroom wall).

However the plastic cover was cracked, and you got an electric shock when standing in the bath, trying to adjust the angle of the shower (but the owner kindly replaced the heater attachment when we complained).

Fortunately the place only ran on 120V I think, otherwise it would have been more serious..

So, what is it about kitchen sinks in the UK that you can't get a voltage off them?

[Skipweasel]

Metal sinks and pipework are all supposed to be connected together with earth wires and clamps and stuff to make sure that whatever voltage they're at, it's the same all through. Ideally, of course, that voltage should be the earth potential...

[John Rumm]

Ideally, no potential... that's the acid test when deciding if something needs bonding - is it capable of introducing a potential into the room/zone/location etc - or to use the regs terminology, is it an extraneous conductive part. A sink by its very nature does not snake about through the fabric of the building - so its not likely to bring a voltage into the room. Left to itself it is an electrically "floating" bit of metalwork. Copper pipes on the other hand do romp all over the house, probably do provide an independent path to earth, hence would need bonding in locations where supplimentary equipotential bonding is required - kitchens, not usually being one of them[1].

[1] The heuristic there is to ask if you are likely to be wet, naked, and barefoot... only don't answer in public, cos we might not want to know what goes on in your kitchen! ;-)

[Skipweasel]

Wild parties, according to Astracast, who refuse to replace our sink, claiming 3rd party damage.