fuse size

Just got my new wiring harness in, it wasn't too bad to do. Just have on e problem, test drove it, and it quit on me , the fuse in the fusible link for the main feed for the panel blew. I had a 30 amp in it. Is that too small, or do I have another problem. I could tell when it started to melt, I had the electric fan and headlights on when I started it . I think that did it. The instruction don't say how big of a fuse It just says to put in a fusible link. Any help is appreciated, I have a cruise tomm morn.


Devin

 

Pretend you have everything on in your car at once, add up all the power requirements, headlights, hi-beams, electric fan, radio, etc. Your fusible link should support that amount of power. It is there for protection in case that main power lead shorts out, which will produce way more amps than anything else on your car.

30 amps is too small, as you found out. Without knowing your electrical system, I'd guess you will be fine with something in the 75-100 amp range. You could go with 150 amps until you do all the math, and be okay.

 

thanks flingdingo
I'll try the fusible link I hope it holds out

Devin

 

You'd be better served to not use a fuseable link but instead use a breaker or, at least, a big fuse for your main. A fuseable link of that amperage could cause quite a fire.

 

You need to size the fuselink to the wire size it is protecting. Rule of thumb for a fuse link is two wire sizes smaller than the feed wire (i.e. 14 awg protects a 10awg). Fusible links are usually 6 inches long and have a hypolon insulation. You should be able to find them at a national auto parts store. If your wire harness feed has two battery feeds to the fuseblock and igntion those both need to be protected. There is also Maxi fuses that replace fusible links but you need the total current requirements to size it correctly. Do yourself a favor and put a relay in there to power the electric fan and also a fuse to the battery feeding the relay it will cut the current down on your ignition switch. Most wire harness manufactures recommend relays for fuel pumps, electric fans, air pumps etc. for large loads.