RS485 data communications and other low
voltage signals can be subject to electrical interference.
This potential can result in intermittent malfunction
or anomaly that is difficult to diagnose. To avoid this
possibility always use earth shielded cables, securely
bonded to a known good earth at one end. In addition,
give careful consideration to cable routing during
installation.
a) Never route an RS485 data communications or low
voltage signal cable alongside a high voltage or 3-phase
power supply cable. If it is necessary to cross the path of a
power supply cable(s), always cross at a right angle.
b) If it is necessary to follow the route of power
supply cables for a short distance (for example: from a
compressor X8I to a wall along a suspended cable tray)
attach the RS485 or signal cable on the outside of an
earthed cable tray such that the cable tray forms an
earthed electrical interference shield.
c) Where possible, never route an RS485 or signal cable
near to equipment or devices that may be a source of
electrical interference (for example: 3-phase power
supply transformer, high voltage switchgear unit,
frequency inverter drive module, radio communications
antenna).
12