While I haven't used the fuse box, I did wire in my radar detector permanently.

 

This should help a bit.
I have a dash cam and a radar detector hard wired here. However they are not grounded in the box but to the body post behind the box.

 

.....However they are not grounded in the box but to the body post behind the box.

I believe that would be true for all the vehicles electrical components. There are grounding posts throughout the vehicle so that very few, if any, components get their ground from the fuse box. The fuse box would have ground points for it's components like plugged in relays.

 

judsonlimited, Is that the junction block under the dash? Any information / links on this? *EDIT* I found a link: Back Up Camera Install that shows that same picture. Thank you.

Have you utilized the fuse box when you open the door? I'm just wondering if I use an Add-A-Circuit if it really matters which fuse connection I piggy back?

 

This is under the dash by your left foot.
I also have used the add a circuit on the other fuse box on the side. works pretty well.

 

You can also grab switched power off the overhead console if you like. I used it for my hardwired brandmotion garage door opener.

 

I have a dash cam wired into the fuse box on the drivers side of the dash. You just need to find the fuse with the correct power (Accessory, Constant, etc....).

 

Where, which fuse location?

 

I will add as well that I had to get a voltage step down for my dish cam. 12v to 5v. Find them on amazon for pretty cheap. Otherwise you'll fry things very rapidly

 

I modified a fuse to mount my 3rd brake light flasher in the fuse block so I wouldn't have to cut the brake wire.