INM 9370-RD Rev 5
8
After mounting the enclosure
Check that:
• it has not suffered any damage,
• the IP rating is not affected; for example, by distortion of the enclosure,
• the mounting bolts/nuts are all tightened as recommended above.
4
INITIAL ELECTRICAL INSTALLATION
WARNING!
Before starting any electrical installation work, ensure that the
incoming trunk connection is isolated from any source of power.
CAUTION
The temperature inside the enclosure could rise to 75°C. Ensure that all cables and
cable glands fitted are rated to withstand these temperatures.
4.1 Overview
Captive screws are used to secure the lid. Loosen these screws to obtain entry.
CAUTION
The lid of the stainless steel enclosure is connected to the enclosure body with a
protective grounding cable.
DO NOT leave the lid hanging by this link cable while work is carried out!
• The enclosure receives power from the incoming trunk cable and requires no
further source of power.
• The equipment shall only be powered from supplies conforming to IEC 61158.
• Type ‘A’ fieldbus cable is recommended for fieldbus trunk connections.
• The terminal blocks for the trunk fieldbus cables have either screw terminal
connectors or cage clamp connectors according to the enclosure model
specified, but both are suitable for cables from 0.5mm
2
/AWG 20 up to 2.5mm
2
/
AWG 14.
On completion of installation, check all blanking plugs and cable glands are tightened
to ensure IP rating of the enclosure is maintained.
Details of the internal wiring for the two enclosure types is provided in Appendix 1.
4.2 Grounding
Two distinct ground concepts should be recognised before wiring of the enclosure
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 in, or
on, the enclosure does not present a hazard to personnel; it also provides a low
impedance earth grounding circuit for any surge protection items used in the
enclosure. An external M10 earth-grounding stud is provided on the side wall of the
enclosure to enable a connection to be made to the local ground.
Use a ring terminal to make a good quality, plant safety-earth connection (4mm
2
cross-sectional area or better) to this bolt and tighten it to a recommended torque of
5Nm.
Note
: It is important to prevent this connection from loosening and also to protect it
from corrosion against the stainless steel grounding stud.
4.2.2 Cable shield ground
The enclosures can be configured by the user to either of two grounding methods. The
user should adopt the one that conforms to their system’s normal grounding
method.
