The nice thing about using the relay system is that only a tiny trickle of current is routed through the light switch and dimmer switch for controlling the relays. The actual electric power for the headlights goes through heavy conductors direct to the relays, then follows a very short path to the lights and then another short path to ground.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!