Quote:
Originally Posted by Mike51Merc
Double the Voltage = Half the Current (AMPs)
Half the Voltage = Double the Current
Ohm's Law E = IR (look it up) tells us that devices that work at half the voltage pull twice the current, and vice versa. This is why 6 volt cars have heavier wires than 12 volt cars; they need twice the current (amps) to make the lights shine as brightly as they do on a 12 volt car.
What that means is that if a device with a fixed output (lightbulb candlepower, electric motor RPMs, etc.) pulls 14 amps at 6 volts, they will only need 7 amps at 12 volts to do the same job.
The bottom line is that on a 12 volt system, you'd want a circuit breaker (and/or fuses) with HALF the rating of your 6 volt ones.
Radio Shack carries circuit breakers that will do the job. They even look like the original ones.
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You're close. Volts x Current = watts. A 58 watt bulb requires 8amps at 6 volts. But 4 amps at 12 volts. The filament will have a higher resistance on the 12 volt bulb to limit the amps. Everyone else is right in that the circuit breakers only see current and do not care about voltage as there is no resistance until they surpass the current rating. At that point the bimetalic strip will curl from the heat and open the circuit. The two metqals have different expansion rates which cause it to curl.