Questions about the Leakage Tester

I have built one of the original single-color capacitor testers, and it works great just out in the open, but I’d like to build one of the dual-color ones and put it in the proper enclosure.

My questions are about the leads.

In Paul’s version, the positive lead is an unshielded cable with a banana termination, but the negative side is a shielded cable with a BNC termination.

First of all, why does one of the leads need to be shielded, and why only the negative one? Are we worried about random noise being picked up like it’s an antenna?

I thought the biggest concern would be leakage through the actual insulation of the probe cables when they touch each other, but I am still a beginner so I’m probably missing something.

Second, what type of coax have you guys used for the shielded probe cable? I looked at some of the Belden cable Paul recommends in another video, but that doesn’t appear to be the type he used as it’s not black.

Thanks,

Jim