"Eycott, George, VF UK - Technology (TS)" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > >> > The earth should go to the earth bonding point on the hull of the >> boat, which should be adjacent to the 12v-ve bonding point. >> >> Yes, the earth lead should be earthed to the hull next to everything >> else. >> - Note, 'next to', not 'with'. Same area, diffrent eather tag. > > Now I have heard this advice before and I am puzzled as to why this is > having always been taught to have a single earth point. Take the > following example, if I have the 12v neutral line from the battery > bonded to a hull using a bolt through the engine bearers, what > difference does it make connecting the earth for the 240v system on the > same bolt or putting a new one in next to it? There must be a good > reason but I can't see what it is..... > The reason given is that should the stud detach itself from the hull and there is a fault on the 240v system making the earth live then the -12v will be live as well.
Personally I have it on one 10mm bolt that is through a threaded hole in the engine bed with a nut locked above that then two lock nuts above the connections so for it to break loose and stay connected you would need to break a 10mm bolt or the engine bed which is 13mm steel ( think that the cables would shear before that...) However if it is just a bolt welded onto the steel then it is possible for it to get knocked off hence the recommendation. Julian
