INM 937x-FB2-Px-SS Rev 1
7
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 Preparation
Loosen the captive screws of the enclosure lid and then remove it to obtain access
to the contents.
• The enclosure receives power from the incoming trunk cable and requires no
further source of power.
• The equipment shall only be powered from supplies that conform to
IEC 61158.
• Type ‘A’ fieldbus cable is recommended for fieldbus trunk and
spur connections.
• The terminal blocks for the trunk fieldbus cables have either screw terminal
connectors or spring 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.
For details of the enclosure wiring for the two system types.
4 .2 Grounding
Two distinct grounding concepts should be recognised before wiring of the
enclosure begins:
a) A protective local ground – which is 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 metal work 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 M8 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.
