Initial Electrical Installation; Overview; Grounding - Eaton Crouse-Hinds Series Instruction Manual

INM9380-RD Rev 2
After mounting the assembly check that:
• none of the component parts have suffered any damage,
• the baseplate of the assembly is not distorted
• the mounting bolts/nuts are all tightened as recommended above.
4

INITIAL ELECTRICAL INSTALLATION

Before starting any electrical installation work, ensure that the
incoming trunk connection is isolated from any source of power.
Assembly temperatures could rise to 75°C. Ensure that all cables and cable glands
fitted are rated to withstand these temperatures.
4.1

Overview

• The assembly receives power from the incoming trunk cable and requires no
further source of power.
• It shall only be powered from supplies conforming to IEC 61158.
• The environment/enclosure in which an assembly is mounted must ensure
adequate separation of the trunk and spur wiring. This may be provided by
means of separate cable trunking or clear physical separation as defined by local
rules. Blue cable trunking is recommended for the IS spur cables to identify that
they are intrinsically safe circuits, while grey or black trunking is recommended for
the non-IS trunk cables. The cable routing should ensure that trunk and spur cables
do not cross each other inside the enclosure.
• Type 'A' fieldbus cable is recommended for fieldbus trunk connections.
• The TTA can accommodate trunk cables with outer diameters between
approximately 5 and 13mm - see Section 4.3.1 for further details regarding
protection rating.
• The terminal blocks for the trunk fieldbus cables have either screw terminal
connectors or cage clamp connectors according to the model specified, but both
are suitable for cables from 0.5mm
For details of the wiring for the two system types see Appendix 1.
4.2

Grounding

Two distinct ground concepts should be recognised before wiring of the assembly
begins:
a) Protective local ground - mandatory
b) Cable shield ground
These two concepts and their implementation are explained below.
4.2.1 Protective local ground
This ground connection is required to ensure that any exposed metalwork of the
assembly does not present a hazard to personnel; it also provides a low impedance
earth grounding circuit for any surge protection items used on the assembly. An M10
earth-grounding stud is provided on the assembly baseplate, which must be bonded
to the body of any protective enclosure and from there to the local plant structure.
Where multiple assemblies are installed inside one final enclosure, the grounding
studs for the individual baseplate must be connected in a "star" formation to the
grounding point on the enclosure.
Note: It is important to prevent these connections from loosening and also to protect
them from corrosion against the stainless steel grounding stud.
WARNING!
CAUTION
2 2
/AWG 20 up to 2.5mm /AWG 14.
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