Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
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3.4.1 LIGHTWEIGHT CABLE<br />
Cable types <strong>and</strong> installation techniques<br />
Lightweight cable, as its name suggests, is cable which does not have any<br />
form <strong>of</strong> outer protective armouring. This type <strong>of</strong> cable is typically used in very<br />
deep water (usually in excess <strong>of</strong> 1000m) where the cable risk assessment has<br />
identified that the cable is highly unlikely to be subject to any form <strong>of</strong> hostile<br />
seabed intervention (e.g. anchoring or trawling).<br />
3.4.2 ‘SHARK BITE’ CABLE<br />
Shark Bite cable was initially developed by AT&T in the USA when they<br />
discovered that the electromagnetic field emanating from the power feed<br />
system in their subsea telecommunication cables was agitating the local shark<br />
population. The sharks would then attempt to bite any surface laid sections <strong>of</strong><br />
cable. To protect the cable, a new design, which provided a light single armour<br />
around the cable adequate to repel any potential shark attack, was derived. The<br />
cable also had additional screening installed in the cross sectional make-up in an<br />
attempt to reduce the amount <strong>of</strong> electro magnetic field propagation.<br />
3.4.3 LIGHTWEIGHT ARMOURED CABLE<br />
Lightweight armoured cable is a lighter version <strong>of</strong> single armoured cable where<br />
the steel armour wires would typically be 4mm in diameter, as opposed to the<br />
4.9mm diameter steel wires which are used in the conventional armoured cable<br />
(Figure 3.2). A typical application <strong>of</strong> lightweight armour would be for a deep sea<br />
section <strong>of</strong> cable which was going to be laid over a rocky seabed area <strong>and</strong> where<br />
the risk <strong>of</strong> abrasion damage to a lightweight type cable was considered to be<br />
high.<br />
3.4.4 SINGLE ARMOURED CABLE<br />
Single armoured cable is a cable type which is typically used in conjunction with<br />
cable burial as a means <strong>of</strong> providing overall protection for the installed cable<br />
(Figure 3.3). This type <strong>of</strong> cable would be employed in areas where the risk from<br />
hostile seabed intervention such as fishing had been identified. This may occur<br />
in water depths anywhere between 50m to 1000m.<br />
3.4.5 DOUBLE ARMOURED CABLE<br />
Double armoured cable would typically consist <strong>of</strong> an inner armoured layer<br />
(similar to the single armoured cable type) with steel wires <strong>of</strong> 4.9mm in diameter,<br />
which would then be overlaid with a second layer <strong>of</strong> armouring with steel wires<br />
<strong>of</strong> 7mm in diameter (Figure 3.4). Double armoured cable is significantly heavier<br />
<strong>and</strong> more inflexible than the single armoured cable which makes it more<br />
difficult <strong>and</strong> expensive to produce <strong>and</strong> install. Double armoured cable would<br />
typically be employed where there is a perceived high risk that the cable may<br />
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