Thread: "Customer may ground if conditions permit" ???

I'm no electrical engineer, but I've noticed that all of the factory wiring diagrams that I've seen for Cincinnati machines include this note for the low-voltage (110v) control circuit: "Customer may ground if conditions permit."

For example, here's a snip from the factory diagram for my 1-B Toolmaster:



Under what circumstances (and why) should the low-voltage control circuit be grounded as shown? The machine runs fine without the ground.

1950 NEC, now it is required to be grounded...Phil

Originally Posted by Phil in Montana

1950 NEC, now it is required to be grounded...Phil

I don't know about that reg, but ground referencing is not normally done. These control circuits usually float, whether it be 12, 24, 48, 90 or 110 volt. They are typically powered by a separate winding on a step down transformer and used to energize control relays and safety interlock circuits. So when trouble shooting a fault, one test lead must reference the return side of that winding not frame earth.

A fuse has been installed, so they want a path to ground to pop the fuse...Phil