Power Distibution Board - Broken stud

[FrankJ]

Here is a data point: We have six of these boards on various robots. We have one a broken stud. Relatively untrained student screwed on a 1/4-20 nut with an experienced mentor looking over her shoulder. Definitely operator error in our case.

We are now powering that PD board through a Wago connector for a test bed.

[Richard Wallace]

The PD shanks are fragile, when compared against steel M6 screws. The PDB doc (here) states, on p.7, that the shanks can shear if torqued to more that 3.9 N-m. That's about four pounds of force at the far end of an eight inch wrench. Not nearly as much torque as is typically recommended for steel M6 screws -- about 10 N-m for Class 8.8 or 15 N-m for Class 10.9.

However, the OP clearly stated that the person with the wrench was a veteran electrical mentor guy. I agree this one is probably just bad luck. One of the best students on our team had similar bad luck a couple of years ago.