Headlights draw around 4-6 amps each at 14 volts depending on the style,ie halogen or standard.Almost all vehicles use an auto resetting circut breaker on the headlight circuit to prevent a temporary problem from plunging you in darkness.You can use a 30 amp fuse instead of the breaker,it'll break the circuit to prevent a meltdown in case of a severe short circuit, but won't nuisance blow .