How to you figure out what fuse you need with different accessories? Like with my Cobra 29 CB radio, I have it wired straight up to the battery with the in-line fuse that came with the radio. What rating fuse would that require? How about for some offroad lights? I'm going to put a aux fuse block in the engine bay to tidy up my wiring and figured I should know this.

 

I use a 30 amp for everything on mine. 12V outlet in the bed, fog lights, off road light, and hard wired power inverter all have there own fuse. I figure if theres any jump in current or theres a short it will be alot more then 30 amps.

Check and see if your CB has a built in fuse. If it does put the same fuse in line.

 

It already has a fuse in-line, when I put in the fuse block I'm going to just use a blade style fuse instead of the in-line.

 

You need to figure out what the normal amp draw is on your accessories. Your CB should say an amp draw on it somewhere. Off road lights, you need to convert the watts to amps (Ohm's law), that will show you the amp draw of each bulb.

Once I figure out the amp draw, I like to round up to the next larger fuse and then add 5 amps to allow for power surges.

My 100w KC's will draw 8.99 amps so I am using a 30 amp on each set of 2 lights (wiring 4 up to 2 per switch).

 

So say my CB pulls like 22 amps, I should put a 30 amp fuse on it? So for 2 130watt KCs on a switch it would be 260watts/12volts = 21.6 amps, so use a 25 amp fuse? I think I got it now.

 

See how much wattage does it consume, and divides by the voltage of your vehicle.

Example, if your radio consumes 100W, try:

100W / 12v = 8.33 A

Or, use a fuse that is imediatelly superior for that value = 10A.

If you have three 130W offroads lights, try:

130*3 = 390W
390W / 12v = 32.5A - At least a 40A or 50A fuse.

 

Yeah thats what I just posted up above. Thanks tho thats exactly what I needed to know.

So if the fuse was under the amount of watts the thing consumes then would it just blow the fuse right? What would happen if say you used a 50amp fuse on a 25amp device?

 

Run a relay for your lights....

 

Oh yeah I know the fuse would be for the switch.

 

This is a super late reply but for others looking for it most CB radios come with a 3 amp fuse inline. When I used to drive over the road I would take out that fuse holder and put in a blade type holder since glass fuses are not as good IMO.

 

well if o run a 50 amp fuse on a 25 amp circuit nothing will happen and if it short the fuse will blow no mater what, however if you over load the circuit then its possible to burn out wires so thats another thing to look out for, and i agree with Fx4wannabe01 put a relay in for your accessory lights, but if you want them to come on with your prkng lights or all controlled by one swithch, say you want to do either of the about, have the switch trigger the relay and have the battery connected so it powers the contacts, and put the accessory lights on the nomaly opencontacts, that is what i did with my lights to protects my parking light cicuit and to save from haveing multiple switches mounted on the dash.

 

and glass buss fuses are perfectly fine and the fuse holders are easy to hide if you want to make the wiring look good.

 

This thread is over 2 years old...

 

really well then why the hell did it showed up on like the top of the list when i clicked on the general techical and electrical discussion

 

Trent was just stating a fact... Dont start a **** storm that you cant handle 894banger.

 

umm i was just wundering why it appeared so high up on the list of threads when its over two years old, and the since the threads appear to be in order by date, and i didn't start a **** storm, that is how i casualy talk so sorry if it came out harsh or like i was pissed off,

 

Well when people USE search functions or find a Thread that pertains to something than get used to OLD threads popping up. that is all

 

ok thank you btm757, that is all i wanted to know, again sorry if my previous statement seamed harsh, but i had no intention of so, and again that's how i causally talk.

 

Someone else randomly posted in it bringing it back up on the list. It was originally posted in 2008 though. I don't even have the same truck anymore lol

 

haha ok, thanks for clearing that up, but your f150 there is pretty damn sexy