How do I wire a 12 volt into my fusebox?

 

depends on what it is you're trying to connect. need more information

 

I am adding nitrous to my mustang. I need to wire my switch into the fusebox. there are a few blank spots. How do I wire into the back of the blank spots and add a fuse?

 

it would be easier to get a fuse holder from the parts store and connect it directly to the hot terminal on the starter solenoid and then run the wire into the car to your switch and back out to the solenoid for the nitrous. this way you won't disturb the stock wiring and accidently knock something loose that you really need to work. it's easy enough to put a wire through the same grommet in the firewall where the speedo cable enters the back of the dash. this way the fuse would be easy to access under the hood whenever you have to service the nitrous system, just make sure to use a properly sized wire for the current the solenoid is going to use.

 

In the same post in another section I suggested he might wire it off the "key on" lead with an in line fuse rather than a direct battery hook up...

Ron