I have very old fog lights with glass lenses (70s?) The halogen bulbs plug in via a wire to the housing. I had them wired to my repop fuse block that was supposed to prevent a short but I got a cab full of smoke as I left the gas station a few weeks back. Does anyone know how how large a fuse I need to avoid this or am I supposed to have a transformer in between the accy and the power? As you can see from the picture the fuse block cooked even after the fuse blew. Luckily I didn't have anything else connected to it.
Yeah use a relay and a 25-30 amp fuse, and try and find what's caused the short. No matter what size fuse you have a dead short will blow it. Posted using the Full Custom H.A.M.B. App!
You must obey Ohms law here, Watts/volts=amps so assuming that the bulbs are 55 watt, you have 110/12 = 9 amps. Throw in some wire run and connection resistance and call it 12 to 15 Amp draw, so 20 amp should cover it nicely. And the closer to the load the relay is the better off you are.
----------------- Yeah..'back in day', 1970's vintage fog lights were "traditional" on almost all '64 and older era hot rods and customs, don't cha' know! Mart3406 ============
Think you missed the "very old 70's" bit they aren't saying all fog lights aren't traditional Posted using the Full Custom H.A.M.B. App!
Bringing this one back from the dead before a whole year is up. I hate to be one of those people who brings dead threads back but I think it is worse when you never post an outcome so here goes: I finally got this one beat... Thanks to everyone for the help and feedback! I did something very close to what mashed posted. I picked up: a per-wired 30/40amp relay, a 20 amp fused switch, 20 amp inline fuse and wired it up. The battery power on Relay prong 30 went to my head light switch. The supply on the switch went to accy on the ignition. I am not great at wiring so these diagrams I found on google made it really simple for me to understand:
I'm connecting a single fog light to a toggle...on the last diagram above..does the line at the "off" on the toggle to the ignition need a fuse as well ?
It comes from the fusebox, in theory, from a fused circuit (typically Accessory circuit that only lets the fog light run with ignition on). The draw is only enough to run the indicator light and the relay. So an extra fuse inline won't hurt but is probably not needed. Just make sure your connections are good and the wires don't rub.
Your question doesn't make sense. In the diagram, power comes from the fuse panel, and is switched on/off by the toggle switch. What part of this are you asking about?
In some of the diagrams I've seen there has been an inline fuse from the power source to the toggle. I was assuming the power was coming from the ignition switch in the diagram.