Supplementry Bonding with previous edition regs

[ackbarthestar]

If bonding has been carried out between extraneous parts, but not to the CPCs, but resistance between all extraneous parts and the CPC terminals of light, shower or what ever's installed give a resistance low enough to prevent voltage rising above 50v, is this acceptable?

Ok,
If you connect all the metal fittings together, assuming you have all copper pipework then it is likely to be main equipotentially bonded at source, in which case you you are creating a local bonding zone in that location. If you now cross bond the cpcs of the circuits entering that zone to the extraneous conductive parts you will achieve a shared R2 between all of the circuits this lowering the Zs of each circuit while providing your local equipotential bonding zone.

That's fine if you are using BS3036 fuses without RCD protection and was the acceptable method of providing protection previously

 

[Amp David]

Do you mean with a connection to the MET, but not to any CPC's or just between ECP's themselves?

Between exposed conductive parts and extraneous and just exposed conductive parts.

 

[Amp David]

Ok,
If you connect all the metal fittings together, assuming you have all copper pipework then it is likely to be main equipotentially bonded at source, in which case you you are creating a local bonding zone in that location. If you now cross bond the cpcs of the circuits entering that zone to the extraneous conductive parts you will achieve a shared R2 between all of the circuits this lowering the Zs of each circuit while providing your local equipotential bonding zone.

That's fine if you are using BS3036 fuses without RCD protection and was the acceptable method of providing protection previously

Even if you have 60898 or 3871 breakers say for lighting, then if you were to test for a minor works say for a replacement shower that had rcd/rcbo, supp bonding still has to provided, for the non rcd circuit/s.

So if all extraneous parts are tiled in behind a bath or boxed in for what ever reason, and there is no possible way to connect supp bonds from extraneous to conductive. But, for example, when you test between the hot, cold and heating you get low readings and between these and light fitting cpc you also have a low reading, if this resistance figure provide the 50 volt or less does it comply?

 

[ackbarthestar]

Even if you have 60898 or 3871 breakers say for lighting, then if you were to test for a minor works say for a replacement shower that had rcd/rcbo, supp bonding still has to provided, for the non rcd circuit/s.

So if all extraneous parts are tiled in behind a bath or boxed in for what ever reason, and there is no possible way to connect supp bonds from extraneous to conductive. But, for example, when you test between the hot, cold and heating you get low readings and between these and light fitting cpc you also have a low reading, if this resistance figure provide the 50 volt or less does it comply?

You can only do so much with what you've got. If access to the extraneous parts is hidden behind tiles you will not be able to supp. bond directly. In most cases cross bonding locally to the hot and cold pipework, radiators etc would be sufficient.

If you are replacing the shower unit you might be able to slip a 4mm2 up and across to the lighting circuit and to other metallic parts. I think that 701.415.2 gives more information regarding this