so all grounding wires on my pontoon meet on an isolated buss bar, which is connected to my battery, which is connected to the motor.
if I'm wrong, speak up.
This is corect....
yep confusing......so, this is my common man explanation...pontoon.
12v DC
All powered equipment sends current out of itself when on. This current is negative (ground). This current needs to meet either at a grounding isolated buss bar or directly to the negative battery post or to the engine ground.
If I connect a negative return from a powered source to my "hull" , I am inducing current through my hull to ground. It'll take the least resistive path, which is to water. I'm inducing a potential current difference....two paths....one directly to the hull and the other from battery through motor/transom/prop.......since it is kinda confusing, just make sure all grounds are to the same final connection...battery/motor.....
Your 12VDC battery has the "potential" to supply 12.7 VDC supply and ground
Connect a 3" long wire and a 30' long wire to the positive terminal on the battery. Now measure the voltage at the end of each wire relative to the ground terminal on the battery.
With enough resolution, you'll find that the shorter cable has a higher voltage (potential) than the longer cable due to resistance of the wire,
Now measure the voltage on each cable using a "ground" other that the battery post. Say, between the short wire and the bus bar and longer wire to the bus in your helm fuse box.
bonding....just an example-
I installed my hot tub years ago so I needed to learn how.
AC high voltage high amps.
One requirement is that all touchable conductive structures touchable from inside the tub have to be bonded to the tub which is , of course, connected to the home panel. The home panel neutral and ground buss bars are "bonded " together in the panel. I have an aluminum gazebo right next to the tub. All structures are on a wooden structure. There is a "bonding" lug on the hot tub. So there is a bonding wire, think it's 4 gauge whatever the instructions required, from that structure to my hot tub.
Although my tub is GFCI protected, if my water was somehow energized and I touched that gazebo, maybe under a weird circumstance i could become the conductor......gazebo's mounted on wood, but not taking that
chance......so it's bonded to the tub which is connected to earth ground through my main panel....
In AC you have 3 wires, hot, neutral (ground) and earth ground.
The important thing to understand here is that neutral and “earth” do not play the same roles as they do in a DC circuit.
Hot and Neutral carry the power, but "earth" in an AC circuit serves as safety (bleed) valve in case of an imbalance of potential between hot and neutral legs of the circuit.
The excess (lost) voltage has to go somewhere. As such, all "earth" (bonding) wires are connected to what is typically a copper ground rod driven into the ground at the point your electrical service enters the home.
Connecting "earth" to neutral is just asking for problems...getting shocked
