I put a CB radio in my XJ yesterday. I wired it to the fuse box using one of those add a fuse gizmos. It turns on without me running the ground wire to anything. Does it need to be grounded?

Might be grounded through its mount.

Run a simple negative wire to a good ground. You dont want your rig to burn up because of a lack of a good ground. It will also help with your output signal with your CB.

X2

X3

1) Concur. There's never any harm in adding a definite ground to something - even if it is grounded through the mount.

2) I don't like those "add-a-fuse" jobs. The OEM fuse panel can only handle so much.

I prefer, instead, to add a fuse block for accessories. The fuse block gets fused (as a whole) as close to distribution as possible - then the individual circuits off of it are fused. Say the fuse block has an aggregate rating of 60A max - I'll wire it up with 10AWG wire, and put a 60A fuse of some variety (ANL or MAXI, usually) right near wherever I pull the power off. Even if I wire it through a high-current relay to be "Hot in ACC" or "Hot in RUN."

Then, the individual accessories get their individual fuses.

Overkill? Perhaps. However, I can honestly say that none of my wiring jobs have ever lead to an electrical fire, and this is with some 30 years' history! I'm cranky about maintaining that reputation...