How strong of fuse do I need for 4, 55 watt fog lights in a car?

Question

I originally bought a set of fog lights for my car. They were 2, 55 watt fog lights which are connected to a remote control box for control from a wireless remote. This system came wired to a 15 amp fuse. I recently purchased another pair of lights and I spliced them into the wiring of the older set of fog lights. After wiring everything together, the lights would work for about 10 minutes while the car was on, and then shut off. I discovered that the fuse blew out and so I replaced it with another 15 amp fuse I have. Of course that blew out too. I'm assuming that because there are 2 more lights, both 55 watt each that there needs to be a stronger fuse. Does it make sense to just get a 30 amp fuse to compensate for the extra wattage or do I need a stronger one?

Answer 1

OK you've got 4 times 55 watts, thats 220 watts total. To find the amps divide by 12 volts, thats 18.3. So you round up to the next convenient size, and add a bit to take care of turn-on surge. 25 amps should work perfect.

Hope this helps.

Answer 2

First answer I would have to go with. Allow for a little fudge and a little surge. The fuse is to protect the wiring from durning up in the event of a dead short. 220 wats but the actual running voltage is closer to 13.5 while charging, sometimes more. Your amperage draw will be 16 to 17 amps. Use a 25 amp fuse and be sure your wiring can handle the load

Answer 3

It depends on how it's wired. if it's wired in series, the amperage would go down and you don't need a bigger fuse. And, maybe the lights wont be so bright. If it's wired in parallel, the resistance would go down, therefore the amperage would go up causing the fuse to blow. Remember, the fuse is to protect the wiring from melting down or causing a fire. If it's wired wrong, and you put a bigger fuse to cure the problem, it will not protect you from the heat problems caused by high amperage. Ohms law and Series & parallel circuits is a good thing to know about when installing lights on a vehicle.

Answer 4

Ohms law buddy will give you the answer.
(55X4)/12 =18.33 so if your input voltage is 12v and the total watts is 220 then you need a 20 amp fuse because they do not make a 18.3 amp fuse
that should protect your circuts.BUT I also hope that you are running those lights thru a relay setup. Other wise your burn up your lights and fry your wiring or switches. Let the relays take the load. and 4 lights on one switch and one relay is too much. wire them in pairs thru relays.

Answer 5

4 Fog Lights

Answer 6

you should try a 25 amp fuse first then go to a 30

Answer 7

If my schooling is remebered correctly, watts divided by volts equals amps, so in theory 20 amp should work, as long as the wiring can support the capacity neccessary.