Supplementary Bonding (Electric shock from bath taps)

[Redhotferrari]

Hi Guys,

House had a bathroom refit about a year ago, just recently started to feel a slight electric current when we first turn on the bath taps.

Have checked and there is no bonding between the hot and cold copper pipes anywhere on the bathroom, should I bond these together with earth clamps? Its not all the time and almost like it builds up a little bit like static which is released when first turing on and not exactly a jolt.

The house had a main earth near/into the consumer unit and all the central heating pipes have been bonded.

Look forward to hearing from you.

 

[Qedelec]

Yes, use 4mm G/Y.

 

[Redhotferrari]

Thanks Qedelec,

I assume by 4mm G/Y you mean 4mm cable with an earth sheaf?

This might be a really basic question, but how does bonding them together ensure safety? Is it because you are creating a loop straight back to earth via the cold mains into the house?

Just curious.

 

[Qedelec]

Equipotential and supplementary bonding is all about making sure all exposed metalwork is joined together electrically thus all is at the same potential, hence equipotential. The danger would come from an appliance fault causing the exposed metal to become live, then there is likely to be a potential between it and an earthed item.
Join them all together and then, even if the earth to the bathroom fails there can be no potential difference.
P.S. just reread your original post, and it would be wise to check you have a 10mm G/Y from the water stoptap to the Consumer Unit and one from the Gas supply pipe to the CU.

 

[Redhotferrari]

Thanks, so as in your first reply, simply use earth clamps between the hot and cold of both the basin and bath and use 4mm Earth and all should be good?

Is there anyway of testing these pipes with a multimeter?

 

[JohnD]

you sound as if you intend to just bond the hot tap and cold tap together.

there is more to it than that.

As well as bonding the hot water pipe, cold water pipe, radiator flow pipe, radiator return pipe, metal waste pipe, iron soil pipe together, you also need to bond them to the earth conductor of all electrical circuits entering the bathroom. this is always a lighting circuit, may also be an immersion heater, CH pump, electric shower, shower pump, cylinder thermostat, electric heater, jacuzzi, shaver point etc.

Lots more in //www.diynot.com/wiki/electric...l_bonding:supplementary_equipotential_bonding

 

[Steve]

In other words, every metal service that enters the bathroom needs to be bonded to every other metal service that enters the bathroom, as well as the earth core of every electrical circuit.

 

[Redhotferrari]

So in other words get a spark in?

The only items that are in the bathroom, metal wise, are hot and cold to bath and basin, shower (mixer type) all the above all tee of the same hot and cold pipe entering the bathroom, radiator and ceiling light.

Do not think I will attempt to sort this myself, but do you mean you have to create a loop between all these items ending up with an earth going into the electric light earth? Bathroom is on ground floor, so this would mean lifting floor boards etc etc