Negative Grounds
by Jim Charles
I recently installed a small fire alarm panel into a fibreglass hulled vessel. I’m kind of new to marine electrics so excuse me if my questions are naive. The problem is that I cant get rid of an "Earth Fault" that keeps showing on the panel. I have tried to get some information from the suppliers however they wont support this panel despite selling it to us!! They suggested the ship may have the wrong type of Earthing System. As I understand it there are two types - floating Earth and negative grounded Earth. I am assuming the negative grounded just attaches the negative wire from equipment to the chassis at an earthing point (prop shaft?), like a car, while the floating Earth is independent of the DC live and neutral. When I asked an electrician about this he told me there was no earth on the boat but I could run a wire to the anode and connect this to the enclosure chassis. I didn’t want to connect the chassis to the negative in case it carried a current so I left it until I found an answer. Given this information can you suggest what type of Earthing system this vessel would have? Click here to read or post comments.
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