Supplementary bonding - must connect electrical earth?

[Dippy]

My supplementary bonding appears to be only in the airing cupboard which is close to the two bathrooms so I understand that it is acceptable. However I was surprised to see that there is only bonding between all the pipes and not to the electrical earth which is present in the cupboard (via the cpc of the radial circuit which supplies the central heating system and back-up water heater).

As the main bonding is very good, the resistance between the supplementary bonding and the main earth terminal is less than that for the radial cpc. So clearly there seems to be no benefit to connect the two. However all the information I have read suggests that they should be connected.

Advice please?

 

[Taylortwocities]

The purpose of supplementary bonding is to connect together all necessary metallic items so that no potential exists between them.

If you connect an earth from another source then you could introduce an external voltage. Even a small potential differnece can be hazardous given the environment of bathrooms (wet bodies).

The required metallic items in a bathroom must be bonded together and these should be bonded to the cpc of any items than are inside the bathroom (eg shaver point, lighting, etc).

there's more on the WIKI at //wiki.diynot.com/electrics:sp...l_bonding:supplementary_equipotential_bonding

 

[RF Lighting]

However I was surprised to see that there is only bonding between all the pipes and not to the electrical earth which is present in the cupboard (via the cpc of the radial circuit which supplies the central heating system and back-up water heater).

Does the radial circuit in the cupboard actually supply any equipment or appliance in either of the bathrooms?

 

[Dippy]

So I should connect the cpc of the lighting circuit which is common to both bathrooms to the supplementary bonding in the airing cupboard?