I need some advice on earth bonding before I have a PIR done. My central heating is earth bonded to the fuse box but there is no bonding on the water pipes in the kitchen/bathroom or on the gas pipes. The central heating boiler is next to the bathroom so is it ok to supplementary bond the water pipes in the bathroom to the central heating bonding. An electrician told me you can connect to the nearest electric socket if its too difficult to get back to the fuse box, so in the kitchen there is a double socket thats not far from the water pipes, if not there is a radiator thats not too far away is it ok to use that instead. Lastly what size earth wire should I be using. I think I read somewhere that the supplementary bonding should be half the size of the main bonding so if the main is 10mm the supplementary should be approximately 6mm, is that correct.