Quote:
Originally Posted by lutronjim
Why is a relay needed? Why not just a fuse?
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Relays are used in circuits to reduce the current that flows through the primary control switch (like a headlight switch). So your using relatively low current to control the relay (for the headlights), instead of running high amps thru the light switch.
A smaller switch or sensor can be used to turn a much higher capacity relay on and off.