[FTC]: HiTechnic Motor Controllers - Motor and Power wires fall out???

[Al Skierkiewicz]

As others have described, there is a piece of metal between the screw and wire opening. This does not automatically push out of the way when you insert a wire and may need a little help from a small screwdriver. When yo insert the wire, the end musts extend beyond the screw prior to tightening. If it does not, the screw will push down on the metal tab forcing the wire out of the terminal. The ferrules described above work well in this application as they will force the metal tab out of the way when inserted. But here comes a big caveat, do not use these for the FRC PD. The PD is designed for a very particular WAGO ferrule that is available from WAGO suppliers. Any other device is not designed to handle the current due to the unique design of the WAGO PD terminals. In general, these terminals and the PD are intended to be used with bare copper (not tinned) or specific ferrules.

[RRLedford]

The proper way of tinning for this type of a screw against pivoting clamp bar connector scheme is to tin only the very tip of wire, and then cut most of the tinned end off, leaving mostly only bare copper to mash down at the point directly under the screw and further out, but with a short zone of tinned remaining at the far tip of the wire.

This produces a reversed wedge effect, such that the tinned tip of the wire is the big end of the wedge, and the clamp piece then squeezes tighter as the wire gets pulled, since the tinned tip will not flatten out as much or as easily as the bare copper did when connection was tightened. Thus, the clamp bar grips the wire at an angle, tighter at the exit and looser further inward, and this effectively locks the wire inside the clamp.

-Dick Ledford