quote:
Originally posted by Syd Bridge
The logic is fairly straightforward. With the switch between V+and load, you are switching full current at 12+ volts.
If the swithch is after the load, you are switching less voltage, as the load has taken its share out.
Sorry Syd this is incorrect. Irrespective of the the location of the switch within a circuit, the voltage across it will be the same when it is open,
this is basic circuit theory. The peak energy the contacts have to dissipate is the same wether a ground or live is switched.
The reason for switch grounds is simply convienience, e.g. an oil pressure switch only required one wire to switch to ground as the engine block is
grounded. To switch a live it would require two terminals isolated from the body, and therefore tww wires in the loom. Same with the horn on older
cars which were a single wire which was grounded to the steering column when you pressed the horn push.
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