Protecting Cable

Nowhere is this more true than beneath the sea, where damage is not going to be noticeable to casual observers – other than fish. Costs associated with failures are usually considerable, and recovery and repair costs also tend to be high. One answer is to enhance the armour around the cable or hose but this is expensive, as well as making it much heavier, stiffer and more difficult to handle. The common solution is to put some extra sheathing around the cable over vulnerable areas, but here comes a problem. How do you thread a long length of cable through a circumferential, tubular sheath? The solution is usually to make the sheath as two half shells and then secure them with clamps at each end and possibly in the middle as well, but this leads to other problems. Unless there is a perfect size match, there are either gaps between the sides of the two half shells or they do not fit onto the cable all the way round. There is also a tendency for the shells to slip past each other as the cable or hose bends, leading to ends of the shells becoming unclamped. The ChallengeOur challenge this month is to come up with the best means of adding additional protection to part of a long, continuous length of pipe or cable. It should, like all solutions, be something that can be applied fairly quickly, which rules out moulding on an extra layer of material. Like all good engineering solutions, it should be totally reliable at the same time as being as simple as possible low cost. The solution we offer solves the problem elegantly and at reasonable cost. While the version for use in the offshore industry costs a certain amount, our readers will recognise it as an idea that can be applied on the small scale at negligible cost. Once you see it, you will consider it obvious – some of our readers may discover that they already do something like this. It is however, considered innovative enough to be protected by patent. For those without access to the web, the solution will be described fully in our December issue. See if you can come up with anything better. Solution The Solution to our November challenge comes from Balmoral Offshore Engineering in Heywood, Lancashire, and is called the 'C' shell, and is primarily intended to protect undersea cables. It consists of two elements with 'C' shaped cross sections, which fit over each other. Each 'C' can be opened out to be popped on as the cable comes off the boat, and there is an inner 'C' section and an outer 'C' element. Because there is a gap between the arms of each 'C', it does not have to exactly size match the cable. The gap between the arms of the outer 'C' is normally on the opposite side to the gap between the arms of the inner 'C', so the cable is protected all the way round. Lengths of 'C' shell can be joined by a method we have been asked not to disclose. Some amateur electricians will recognise the technique as a means of safely protecting cables passing through holes in chassis when there is no properly sized grommet in the toolbox. The 'C' shell is commonly improvised by carefully slitting and removing a length of outer insulation from a length of mains cable.