Extra Negative Wire

Greetings! I’ve got a 2003 Triton Tr17 w/ Mercury 90. I bought her in 2005 and she’s been wonderful. A question I have though is why are there two Negative wires that appear to do the same job? One is black and it is the ground for the accessories. There’s also a green wire that grounds too. Is it supposed to be a Bonding wire? Is it supposed to be connected some place else?

Sounds interesting. Most boats use black for the negative and not green. Is it marine grade wire? I bet it goes to something added aftermarket. A fish finder or lights or something.

In the AC world GREEN is used as a grounding wire to protect a person that is using an electrical device. Should the device short out and have a metal shroud, green wire tied to ground will prevent person from taking a shock.

Four sonar devices, three pumps for aerator/bilge/pumpout and the lights/horn.
These accessories were spread out to two batteries. Many years ago I changed to just one main battery for all non-trolling motor devices.
So the green negative is now an unnecessary wire.
I could be wrong about all this but I’m not too worried about galvanizing my prop or shocking my fingers.
I’ll report back if I explode!
Thanks, ol’ Hotdogneck