Installation 2-3
MN1269
General Wiring Considerations Care should be taken to see that all interconnecting wiring is sized and installed in
conformance with the National Electrical Code (NEC) or Canadian Electrical Code (CEC)
and other applicable local codes.
To minimize electrical interference problems, interconnecting wires should be arranged in
groups. As a minimum, two groups should be used; (1) high current, high voltage power
wiring such as main power input, 115 VAC for fans, relays, contactors, etc. DC wiring for
motor power and (2) low level signal wiring such as input speed commands, tachometer
feedback, inhibit/enable signals, etc. It is recommended that wire groups be separated
by at least one foot, or run in separate grounded conduits. All wiring should be kept as
short as possible.
As a general rule, use only wires of adequate size for their length and current being
carried. Specific recommendations for each major group follows. For critical
applications, finer subdivision into wire groups of like functions is advised.
Power Wiring
All power wiring for the cooling fans, motor power and input power connections should be
no less than 16 AWG gauge or equivalently rated wire. It is suggested that power wires
be run as twisted pairs, i.e., twist the wire carrying current with the same wire returning
the current. Twisting the wires will reduce radiated electrical noise. In systems
particularly sensitive to electrical noise, use of shielding for the motor power wiring might
be considered.
Grounding
Proper grounding helps guard against electrical shock to personnel and can reduce the
effects of electrical noise interference. Each chassis/power supply assembly should be
grounded. One mounting bolt can be used to attach a ground wire. The chassis ground
wire should have a green or green with yellow stripe insulation. In addition to the chassis
grounds, the cabinet which houses the equipment should have a separate connection
direct to earth ground on the power distribution panel.
The system ground should be designed in a tree fashion with individual ground wires
converging to a single earth ground point. Ground wires should be short and large
enough to carry the maximum short circuit current rating of the circuit, as determined by
the fuse rating on the incoming power. Consult local governing codes for compliance with
safety regulations before finalizing the grounding system.
Servo Systems Co. • 115 Main Road • P.O. Box 97 • Montville, NJ, 07045-0097
(973) 335-1007 • Toll Free: (800) 922-1103 • Fax: (973) 335-1661
www.servosystems.com
