Originally Posted by Zotter
Some folks also suggest fusing the ground side. That way if there's a short 'upstream', the hot side of your farkles aren't likely to be used as a ground path for something else - destroying said farkle.
I don't understand
the logic for this one. If all the hot leads to the accessories are fused there is no need for a fuse on the ground side to protect the accessories.
If two hot leads are shorted together for all practical purposes nothing happens. If an accessory on one of the circuits starts shorting out for some reason it will blow the fuses for both circuits. As far as any other accessory connected to the two hot circuits are concerned this isn't any different than turning them off.
If a power and a ground lead short together you get sparks and the hot side fuse will blow. As far as any accessory connected to that hot circuit is concerned this isn't any different than turning it off.
If two ground circuits short together, aside from any ground loop issues, who cares. Chassis ground systems seem to work just fine without wiping out multiple accessories because a wire shorts someplace.
If you have un-fused hot wires running around your bike that get shorted to ground circuits then where there is smoke there will likely be fire. Your accessories will most like be be fine as long as you put the fire out quickly enough
If by upstream you mean that the positive side of fuse box pigtail is not fused at the battery and by some circumstance the ground side of the fuse box pigtail shorts to the hot side and becomes hot, the result would be the accessories would have 12V on both their positive and negative sides. That is no different than having 0V on both sides as the voltage potential between the two connections would be 0V. There will be no current flow through the the device in either direction. If an accessory has a chassis ground in addition to a ground wire and they are shorted together inside the device then the chassis ground will provide a current path to ground as long as the wiring survives. If this is a concern then the best solution is to fuse the positive side of the fuse box pigtail at the battery not the ground.
The only way an accessory hot side would look like a ground return is if the hot and ground side circuit wiring is reversed. No single short circuit can ever accomplish this. It requires two short circuits, two grounds to two hot leads that results in a power reversal, which will probable only happen when stupid (that 's me
) wires it that way.