i'm fascinated with electrical but baffled at the same time. so, since i don't want to burn my 4runner to the ground, i'll ask here first

i'm going to install an aux fuse panel to add more fun gadgets this summer but i'm unsure of what fuse to use and when. specifically, i'm putting in some sunvisors with lighted mirrors and the Homelink feature, i can handle the +/- wiring just fine but how do you know how big of a fuse to run to certain electrical additions? i'll be using constant power to these so i can admire myself in the mirror at night when the key is turned off and be able to use the garage door feature without putting the key in the ignition. so, again, is there some equation for determining what size fuse to run and if so, how do you determine that?

also, i'm going to install some fog lights and possibly some driving lights. i noticed that Ritzy and some one else has little radioshack LEDs wired near the instrument cluster to show when the lights are on/off so you don't forget to turn them off. just where do you connect the power wire of the LED to make it turn off and on with the switch?

sorry, one of these days i'm going to lay off the 4runner mods and take some classes at the community college and get sum lernin'!

thanks in advance

 

I know it's from those "other" 4x4 people, but...
I stumbled across this link the other day, and it seems pretty comprehensive. It goes over fuse selection, terminology, alternator capabilities, a little relevant math, etc.
...Might help, just ignore the banners on the top and left side!


.::EDIT::. ...left out the link the first time around, duh:
http://f150online.com/tech/electrical1.html

 

Usually one of two things determine the fuse size. How much current the device you need will pull or how much current the wire you plan to use can handle. I usually use like 14-16 ga. wire for smaller circuits and a 15 amp fuse. Heavier wire or a higher load device and you need a bigger fuse. You can also use smaller fuses, but I like to keep the number of different fuses I need to carry to a minimum. I use a small 6 circuit fuse block in my '85, it has held up fine for over 10 years now:
- http://www.4crawler.com/4x4/CheapTri...werPoint.shtml

 

I don't have an aux fusebox, but I generally tend to use 15A fuses for low-draw circuits. I use 25A for higher-draw. But I use 12 ga for everything. partially because I tend to be safe rather than sorry but mainly because I get 100' spools of it from my friend free

 

Low draw junk gets 10-15 amp fuses, bigger stuff gets 30amp fuse.

Wire your fuse block like this: + from battery to wire, wire to 30amp circuit breaker fuse (this will prevent overload, if the circuit overloads it will shut power off), breaker fuse to fuseblock. Then wire it out to whatever you want. I always used 14ga or better wire, this insures no issues.

 

Very similar opinion. I use 8 gauge wire to accessory blocks, with a 60A circuit breaker or fuse on the "master" accessory line (under the hood). Once at the accessory fuse block use;

10A fuse, 16 ga. wire for: small interior stuff (Lamps, CB, radar, homelink)
15A fuse, 14 ga. wire for: big interior stuff (Radio, extra 12V outlets)
20A fuse, 12 ga. wire for: Say a pair of 100W lights
30A fuse, 10 ga. wire for: a 400W inverter, electric coolers

Match your accessories to the above "groups" and you'll be safe. And do take classes - there's a lot of math to determine what wire gauge/lengths are safe.

 

sorry for getting back so late...

thanks for all the links and suggestions. this will make things go much smoother and i know i'll have it done right. i appreciate the info

patrick