Engineering Documentation

Table Of Contents
Chapter 1 Wiring Regulations and Specifications
Grounding
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Conduit spacing
NOTE:
Use cable tray spacing for non-metallic conduit.
The minimum distance between adjacent conduit runs.
The following guidelines reflect the recommendations given in IEEE 518-1982 for
locating network wiring in proximity to sources of interference:
For (ALN) trunk AIs, AOs, and DIs with circuits greater than 120 volts and carrying
more than 20 amps:
Cable tray spacing = 26 in. (660.4 mm)
Cable tray and conduit spacing = 18 in. (457.2 mm)
Conduit spacing = 12 in. (304.8 mm)
For circuits greater than 1000 volts or greater than 800 amps:
Cable tray spacing = 5 ft (1.5 m)
Cable tray and conduit spacing = 5 ft (1.5 m)
Conduit spacing = 2.5 ft (0.8 m)
Grounding
The following topics are discussed in this section:
National Electrical Code Grounding Guidelines Compliance [ 16]
Earth Ground Current Loops [ 16]
Single Earth Ground for AI, DI, and AO Circuits [ 17]
Equipment Grounding System Requirements [ 17]
National Electrical Code Grounding Guidelines
Compliance
Grounding must comply with National Electrical Code (NEC) guidelines for grounding
of electrical equipment. Under no circumstances should equipment be installed in
violation of local electrical codes. In most cases, NEC guidelines have been
incorporated into local electrical codes.
Earth Ground Current Loops
Earth ground current loops can interfere with AI, DI, and AO circuits. Building electrical
grounds connected to the automation system must be referenced to the same
potential levels within a facility.
CAUTION
Conduit entering an enclosure must be grounded to the enclosure.
If a poor electrical connection is found, scrape off the paint under the conduit locknut,
tighten the locknut, and retest.