Bonding in bathrooms is internal to the bathroom only â€“ so there is no need to run any earth cables to the CU.
Bond together all pipework, and take this to the cpc of each circuit that enters the bathroom.
So for example if you had a shower, heater, lights and fan. You would run a 4mm cable from either the light switch, fan, light fitting, shaver point to either the shower or shower switch, and then to the heater. This would also be connected to the pipework.
You dont need to bond to metal pipework which is fed via plastic pipework, as long as the transition is in the bathroom. You donâ€™t need to bond a metal bath if it is fed via plastic pipe and plastic waste.
It can be quite logistical deciding how and what to bond, as each bathroom is different.
Thanks for that most helpful, you say about plastic pipework, what about plastic speedfits connecting the different pieces of copper pipework, would you have to earth bond each individua copper l pipe looping the earths together?