hey my wife broke the switch off my off road lights there hard wired from my battery with a 30 amp inline fuse i originnally put this switch in myself but i forgot what kind i got the guy at the part store said a 10 amp switch would work but logically a circut is only as good as its weakest link so it wouldnt make sense to put a smaller amp switch with a 30 amp fuse or the fuse wouldnt do its job is that right or will a 10amp switch really work?if not should i get 30 and above?

 

First you need to determine how much wattage your switch is controlling. Two 100 watt bulbs would be 200 watts on your circuit.

So P=IV
200watts=I*12volts
I=16.67amps

You always want the fuse to be the weak link in the circuit. If your switch is under rated do you really want that to blow and possibly catch on fire? In the example above get a fuse that's rated at 20 amps and a switch rated at something higher than 20 amps.

 

ok cool thats what i thoguht im prolly gonna get a 20 amp fuse and a 30 amp switch because that 30 amp fuse in there could heat up those wires too hot from what i hear i dunno why theres a 30 amp fuse in there

 

100 watt lights

 

It's not the fuse that would make the wires hot, it's the current that the lights would draw. Find out the wattage of the lights to figure out the current. Then from the current we can figure out if you have the correct size wire. The wire size will be marked on the wire every foot or so as something like 14awg or 12awg or another size. The only reason the fuse size would cause the wires to get hot is if there was a short in the wires. The fuse is just a safety switch that opens the circuit in case of a short, it's transparent otherwise.
I hope I'm not getting too technical on you, but if you give a man a fish you feed him for a day - teach a man to fish and you feed him for life.

 

Sorry, you must have posted while I was replying.
So that's 100 watts for each light and there are 2 lights? Anything else on this circuit?
Now we need to get the wire gauge .