MT014 300A ON-OFF Battery Isolator Switch The MT014 is built for DC systems that pull real current. With a 300 amp continuous rating it sits comfortably above the average marine isolator, so it can serve as the main break on a boat where windlass, inverter, bow thruster and engine all share one feed — instead of being limited to a modest accessory circuit.The working window is 12 to 24 volts DC. Two-position operation keeps the logic simple: turn the dial to ON and the