I've run an earth 10mm to main water supply in house and there is currently no seperate earths run to bathrooms. All circuits are rcd protected and when i checked continuity at sink pipes using flying lead the reading was fine but when i checked at the shower there wasn't any continuity. Checked above the shower and noticed some of the pipes were plastic. I've been told by someone now that I need to run a seperate earth to the shower?? Is this correct?