OK. Materials specs battery 12 volts 12 ah (as usual ) fuse (12 volt/1 ampere (let's say)) bulb (12 volt/5w ) Ok, the line 1 joined the terminal - and + causes it to short-circuit. but it's have own fuse to protect itself. so, it will not affect the line 2? as you may notice, both line have their own connection. they are directly put on the battery. um,what's your comment? am i correct? i hope so.