A marine cable installation is only as good as the point where the cable enters something.
The cable itself can be perfectly specified, correctly routed and properly supported, and the
installation will still fail at the gland - because that is where water gets in, where the
armour has to be terminated and earthed, and where the mechanical load of a cable being pulled
or flexed is actually taken.
Eaton's Capri BVL and BVP ranges are purpose-made for that job in marine and naval service,
built to DTCN 5975 CA standards. They accept both non-armoured cable and steel wire braided
armoured cable, which matters because the two need entirely different treatment: an armoured
cable's braid has to be clamped and bonded so it carries fault current and provides mechanical
restraint, and a gland that only accommodates plain cable cannot do that. Depending on the
model they are made in natural brass or polyamide, accommodate a locknut, and achieve an IP54
rating along with what Eaton describe as a perfect tensile strength. Two operating temperature
ranges are offered across the ranges to suit different cable entry requirements.
The brass and polyamide choice is worth making deliberately. Brass is the traditional
marine material, mechanically strong and able to take a firm armour clamp; polyamide is
non-metallic, lighter, and does not enter into galvanic corrosion with the structure it is
bolted to - which on an aluminium superstructure or in a permanently wet space is a real
consideration rather than a theoretical one.
On the cable itself, we specify against the project rather than offering a single part.
Cable for shipboard and offshore use is type-approved by classification societies, and a
surveyor will look for that approval against the drawings - so the type, the fire performance
(flame retardant, and low smoke halogen free where the specification calls for it), the
screening and the armour all follow from the rules the installation is being built to and the
electrical environment it sits in. We supply to your cable schedule with the certificates,
rather than quoting a type and hoping it satisfies the survey.
The details that decide whether a run behaves are settled at design stage: length and volt
drop, bend radii, segregation from power circuits, and the gland and termination detail at each
end. Getting those right is what avoids the intermittent faults that are unpleasant to trace
once everything is closed up and painted.
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