I have heard of it, its usually the plumbers that demand it, some sort of gas regulation possibly? The only place you would need to supplementary bond a boiler like this to satisfy the iee regs is when it has been installed in a bathroom / spec locn.
Main bonding needs to be applied to any extraneous conductive part entering the house (ideally within 600mm of entry).
Main bonding needs to be applied to any extraneous conductive part entering the house (ideally within 600mm of entry).
