3 Way Bilge Pump Switch Panel Wiring

Hi All,

The black wire.

Does this get earthed or run back to battery negative terminal ??

Thanks,
Mike.

 

That's the earth or ground for the light in the switch.

 

There's really no "earth" on 12 VDC circuits, just a hot leg, the device and a return to the negative leg, to complete any circuit. From a technical standpoint you don't need to return to the ground post, you can measure resistance on just one side, like a fuel tank sender, but in general, if you have power coming into a device, in order to energize it, the "loop" must be completed. In the case of a pump, you break the hot feed going to the pump with a switch, so when you want you can stop or start the flow of electrons through the "loop". To directly answer your question, yep the black wire goes to a busbar in the dash or instrument panel, which will eventually take the juice back to the battery's negative terminal. Think of 12 VDC circuits as a single wire, going from the positive to the negative posts, with some kind of resistance and control devices attached in route.

 

Thanks PAR