[Ross Nicol]

I have the master switch in the +ve lead on my car.You can buy a switch with an auxiliary contact to cut the alternator's field circuit but I haven't found it necessary in the cars I've wired.The Clubman I've just finished has the switch in -ve battery lead. I agree the lead with the switch in it should be as short as possible. The advantage of having the master switch in the positive lead is that an alarm/light/fire ext bomb/tuner memory/clock or any other very low current circuit can be wired to the hot side of the switch and still have power when the switch is off.Not technically correct for the scrutineers who want to see total isolation, but much more practical for a road/track car.

Ross