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Baseplate Safety Grounding The following recommendations are offered, but applicable safety codes for your area or equipment type should also be consulted. The baseplate’s metal back must be grounded using a separate conductor; the baseplate mounting screws are not considered to be an acceptable ground connection by themselves. Use a minimum AWG #12 (3.3 mm2) wire with a ring terminal and star lock washer under the head of one of the baseplate’s two lower mounting holes. These two holes have openings to the side to allow connecting a wire and ring terminal under the head of a mounting screw. Connect the other end of this ground wire to a tapped hole in the panel that the baseplate is mounted to, using a machine screw, star lock washer, and flat washer. Alternately, if your panel has a ground stud, it is recommended you use a nut and star lock washer for each wire on the ground stud to ensure adequate grounding. Where connections are made to a painted panel, the paint should be removed so clean, bare metal is exposed at the connection point. Terminals and hardware used should be compatible with the aluminum baseplate material.

Programmer Grounding For proper operation, a computer (programmer) running PLC software must have a ground connection in common with the applicable baseplate when connecting to a CPU or intelligent module such as a PCM or DSM. Normally, this common ground connection is provided by ensuring that the programmer’s power cord is connected to the same power source (with the same ground reference point) as the baseplate. If the programmer ground is at a different potential than the PLC ground, a shock hazard could exist. Also, damage to the ports or converter (if used) could occur when the programmer serial cable is connected between the two. If it is not possible to ensure this common ground scheme, use a port isolator (IC690ACC903) between the programmer and PLC serial port connection, and avoid touching the programmer and PLC at the same time.