Mystery wire

[sogood]

Hi all. Just working my way through the variety of inoperative electrical items on my boat. The item in question is a 5.7 litre Mercruiser with an Alpah 1 Gen 1 outdrive. I discovered a "stray" wire that looks like it should do something and wondered what it is. It's a spiral/twisting Green wire, with a lug attached to the end. I don't know where it originates except that it appears out of a loom on the inside of the transom and I'm getting tired tracing and testing random wires, so maybe some wise sage on here can help?

​Thanks in advance and pics attached.

 

[Bt Doctur]

Green wires are usually bonding wires and can be connected to any bolt on the motor .All underwater fittings should be bonded together including the bilge drain fitting.

 

[sogood]

That was quick! Thanks. I kind of thought that it was an earth/ground of some sort! I'll hook it up tomorrow and thanks again.

 

[alldodge]

That's not a factory crimp lug on there, it may go to ground but who knows if someone added it. Have an engine serial number?

 

[Fun Times]

Bonding Systems
Bonding simply means wiring all the boats underwater metals together. This is done because of the galvanism caused by the different metals. By wiring them together, the differing potentials are equalized. Bonding does not solve problems of galvanism or electrolysis, but it does spread the the flow of current around over more metal, so that 1/4 volt or so won't cause any damage. Whereas if that 1/4 volt were going to one small seacock, it would probably eat it up in a hurry. In other words, bonding lessens the effect of small amounts of current. On the other hand, it also spreads it around to all underwater metals so that higher currents end up damaging everything.​

Bonding systems use wire and ordinary crimped ring terminals. After a while these get wet and corroded. Electricity doesn't flow very well through corroded metal, so your bonding system after a while stops working. To maintain it, simply cut off the old terminals and install new ones. Do you have wires attached to sea cocks with hose clamps? Forget it. This is putting stainless and copper together, which are galvanically incompatible and it won't work.​

http://www.marinesurvey.com/yacht/ElectricalSystems.htm