Why 2 ground wires?

[sidenberg]

The wiring diagram in my Baylinner manuel shows 1 #10 ground wire that runs from the negative battery post to the negative connection at the fuse block behind the dash and then another #16 ground wire in the harness running from the motor ground connection to the negative connection at the fuse block behind the dash. I discovered this after finding the ground wire in the harness had been disconnected by a previous owner after it had melted. Is this wired with 2 separate grounds for added protection in case one fails, as mine did, or is there another reason?

 

[NYBo]

Re: Why 2 ground wires?

I thought you might be reading the diagram wrong, but I checked the manual for my boat and it is exactly as you describe. The 16 gauge wire provides the negative leg of the ignition circuit. I think it is done this way for the kill switch circuitry.

 

[Silvertip]

Re: Why 2 ground wires?

There are two electrical systems in a boat. The 10 gauge wires from the battery to the fuse panel power the panel and the associated circuits. The engine harness also contains a 12 volt feed that gets its power via the large battery cable. The engine harness feeds the ignition switch for choke, starter, and the accessory circuit which is intended for instrument power. Large current draws must not be fed from this circuit as the ignition switch is not designed to handle those loads. A ground is inclkuded in the harness because the igntion circuit is grounded to kill it. This circuit works in conjunction with the kill switch when the lanyard is pulled. You might want to check operation of that circuit.

 

[sidenberg]

Re: Why 2 ground wires? I still don't get it.

Re: Why 2 ground wires? I still don't get it.

I still don't get it. Everything that is wired from the fuse panel is grounded via the 10 gauge ground wire that runs from the fuse panel directly to the battery. Everything that is wired through the harness ,including the ignition etc., is sourced from the connection screws on the outboard motor, which is also grounded via the 4 gauge ground wire that runs from the motor to the negative on the battery. So the 16 gauge ground wire in the harness seems to just give another ground connection route to items wired from the fuse panel. So why is it there? See the attached diagram