Re: Shore Power Ground
Let me begin by saying that there are few things on this earth that confuse me more completely than anything electrical...AC or DC. I also want to make it clear that my sole intent in making this post is to further intelligent discussion that may clarify things for myself and others. The small problem regarding mistakes in wiring a boat is increased galvanic corrosion. The big problem is that you can be made dead.<br /><br />When I started reading this thread my first thought was that the advice being given was incorrect...that the AC and DC circuits must be kept separate....just "knew" that. Long story short, I went to find various articles on the subject in a DIY marine maintanence magazine that I subscribe to. Just my luck, the experts are not in agreement here. Of course, on this subject, it is possible that I read...but don't understand. I quote:<br /><br />"For integrated DC and AC panels, marine electrical standards require that a physical, non-conductive barrier, be provided by the manufacturer between the DC wiring and the AC wiring to prevent accidental crossover of the two power sources, or contact with high voltage supply or connections. DC and AC circuits can also be handled by matching, yet separate, main electrical panels." This says to me that the systems should be separate. However...<br /><br />In another article by the same author, three years earlier (1998) "American Boat & Yacht Council (ABYC) recommends that the incoming AC green ground wire be bonded to the DC ground on board. This common ground provides protection from electrocution in the event that AC current escapes from the AC wiring on board (i.e. through a short in a AC battery charger). This common ground, however, can set the stage for major galvanic corrosion problems, since stray current in a marina can enter a boat through the AC ground wire and pass into the DC system."......"If the incoming green AC ground wire is bonded with the boat's DC ground, install a galvanic isolator or isolation transformer to prevent stray current from following that path."<br /><br />If you do any amount of reading on this subject you will find that there are a great many people who think the ABYC has cranial rectal inversion here and that bonding is not a good idea. As I stated at the beginning...I am clueless. One of the arguments against a common AC/DC ground is that if you have a short on the AC side...you are sending live AC current into the water via your thru hulls, prop shaft etc. Make sense?<br /><br />Hoping to learn something from the forthcoming discussion. Best Regards..........John
