Electrical Gurus help

[georgeramos]

I bought some used amber fog lights off ebay and they only have one wire going to the bulb with the other end of the loop being a metal "arm" that contacts the inside of the case to "ground" the system I guess.

My questions are a) does one wire mean a 6v light? b) if so can I convert it to 12v or is there a way to use a 6v light? c) if it is 12v how do I set it up? I want to use a secondary toggle switch and a relay.

Thanks

[aj81spider]

1 wire does not necessarily mean a 6 volt light (and if it was built in the last 20 years I'd be surprised if it was 6 volts). It does mean that your case needs a solid metal to metal connection to the body of the car.

You can check the bulb in the light to see if it is a 12 volt bulb (should be marked somewhere on the bulb). If there is no bulb then buy a 12 volt bulb and you are all set.

Basically it's voltage to the wire, through the bulb to the case to the body of the car. The bulb is the only thing in the circuit and determines the voltage. A six volt bulb will be very bright, burn out quickly and conduct a lot more current than a 12 volt bulb if you connect it to your 12 volt system.

To set it up with a toggle switch and relay connect one side of the relay coil to ground, one side to your switch. Connect the other side of the switch switch to a convenient source of voltage (through a fuse!). I'm assuming you meant an on-off switch and not a toggle switch, as that will involve substantially more complicated wiring.

Take the switched contacts of the relay, connect one side to your wire on the light. Connect the other side to a source of 12 volts (like the alternator output) again through a fuse! I would use a small fuse (5 amp or less) on the coil and a larger fuse (8 amp) on the switched contacts.