Site Considerations for Equipment Installation, Grounding, and Wiring Manual
D301452X012
October 2019
Grounding and Isolation 7
Section 3: Grounding and Isolation
This section covers the following topics:
▪
Power and Ground Systems
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Importance of Good Grounds
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Earth Ground Connections
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Isolating Equipment from the Pipeline
3.1 Power and Ground Systems
Controllers and flow computers from Emerson Remote Automation Solutions support DC power
systems. AC power supplies are not provided. Our devices typically include a ground lug that
accommodates up to a #4 AWG size stranded copper wire for establishing a connection to Earth
ground.
3.2 Importance of Good Grounds
Controllers and flow computers are used in control systems that must operate continually and
within their stated accuracy over long periods of time with minimum attention. Failures resulting
from an improperly grounded system can become costly in terms of lost time and disrupted
processes. A properly grounded system helps prevent electrical shock hazards resulting from
contact with live metal surfaces, provides additional protection of equipment from lightning strikes
and power surges, minimizes the effects of electrical noise and power transients, and reduces
signal errors caused by ground wiring loops. Conversely, an improperly grounded system may
exhibit a host of problems that appear to have no relationship to grounding. It is essential that the
service technician have a good understanding of this subject to prevent needless troubleshooting
procedures.
Devices must be installed in accordance with the National Electrical Code (NEC) ANSI/NEPA-70.
Installation in hazardous locations must also comply with Article 500 of the code. For information
on the usage of these devices in a hazardous location, see the appropriate sections of the device-
applicable hardware manuals. For information on units in Class 1, Device 1, Groups C & D
hazardous locations, refer to the instruction manual for the respective devices.
3.3 Earth Ground Connections
To properly ground the device, the unit’s chassis ground must ultimately be connected to a known
good earth ground. Refer to Establishing a Good Earth Ground and Ground Wire Considerations in this
section.
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