[rotorwrench]

The old 3-brush units only need to be grounded for one of the two important connections. The other is access to the battery through the bus for charging. The cut out is just an automatic on/off switch for the generator. The two highest current draw components (lights & horn) are also attached to the battery end of the cut out so the current won't have so far to travel. The longer the wire, the higher the resistance. I's best to have as short a wire as possible to those items.