I must be paranoid! I have that box pictured - and a cheap multimeter from Harbor freight and a more expensive one (that self zeroes) from Sears. I always check before i screw them on anything, but since i only run REOs and a Silver Bullet - I am probably ok even if there is a short. My A7s will not seem to give me a reading at all on that black box though.
T
The A7's center post can be adjusted down a little to make contact with the ohm meter. I always have to move them down a little. Just be sure to move it back up before putting on your REO.