Terminator said:
Marc_w,
You always match the wire to the source. ?Your thinking is what causes electrical fires in cars, houses, etc (i.e. never planning on USING the maximum power). ?A typical home repair that is made is when a homeowner has a problem with a breaker that keeps tripping and replaces it with a larger breaker. ?Now, somewhere in the wall the wire will overheat and burn.
Actually, if you re-read marc_w's post, you'll see that he is advocating the opposite of what you say.
When replacing the alternator with a higher capacity unit, it's the heavy gauge wiring between the alternator and the battery that will take an increase in current. That is why he was recommending to increase the size of the cable. This is because the increased alternator capacity can increase the charging current that is available to the battery.
The rest of the vehicle wiring is not an issue. The current flowing though those wires is a function of the load on those wires, and not the maximum current capacity of the alternator. Just because the alternator can supply more current does not mean that the loads on the far end of the wires will draw more current. This is assured since the voltage output of the new alternator is the same, the load will not see any difference.
Adding the higher capacity alternator will not stuff more current down the existing vehicle loads than before, it will simply allow additional loads to be added (assuming that they tap in at the alternator, or at the battery after a larger alternator/battery cable was installed.)
The rest of the vehicle wiring is still protected by their fuses and fusible links, as these are not being changed.
To return to your house wiring example: this is not a case of increasing the circuit breakers while leaving the wiring untouched. This is equivalent to upgrading the electrical service to your house. For example, to go from a 100 to 150 amp service, the cable from the pole to the house needs to be upgraded with a larger one, and a new main breaker needs to be installed (and possibly an additional breaker panel.) However, none of the branch circuits are changed: the wiring for these and the associated breakers remain the same.
-- SS