Radio Frequency Interference; Physical Protection; Grounding - Simrad ES70 - INSTALLATION REV A Installation Manual

Simrad ES70
• To allow for future expansion of the system, all cables should be allocated spare
conductor pairs. Also, space within the vessel should be set aside for the installation
of extra cables.

Radio Frequency interference

All cables that are to be permanently installed within 9 m (30 ft) of any source of Radio
Frequency (RF) interference such as a transmitter aerial system or radio transmitters,
must, unless shielded by a metal deck or bulkhead, be adequately screened by sheathing,
braiding or other suitable material. In such a situation flexible cables should be screened
wherever possible.
It is important that cables, other than those supplying services to the equipment installed
in a radio room, are not installed through a radio room, high power switch gear or other
potential sources of interference. Cables which must pass through a radio room must
be screened by a continuous metal conduit or trunking which must be bonded to the
screening of the radio room at its points of entry and exit.

Physical protection

Cables exposed to the risk of physical damage must be enclosed in a steel conduit
or protected by a metal casing unless the cable's covering (e.g. armour or sheath) is
sufficient to protect it from the damage risk.
Cables exposed to an exceptional risk of mechanical damage (for example in holds,
storage-spaces and cargo-spaces) must be protected by a suitable casing or conduit,
even when armoured, if the cable covering does not guarantee sufficient protection
for the cables.
Metallic materials used for the physical protection of cables must be suitably protected
against corrosion.

Grounding

All metallic cable coverings (armour, metallic sheathing etc.) must be electrically
connected to the vessel's hull at both ends except in the case of final sub-circuits where
they should be connected at the supply end only.
Grounding connections should be made using a conductor which has a cross-sectional
area appropriate for the current rating of the cable, or with a metal clamp which grips
the metallic covering of the cable and is bonded to the hull of the vessel. These cable
coverings may also be grounded by means of glands specially intended for this purpose
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