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Gelling Together

Don Lucas, Managing Director of GH Lucas explains the economic reasons for choosing ‘Gel’ filled cable-jointing products above the established resin. Having graduated in engineering, Don has spent 40 years promoting cable management and cable gland products to the electrical trade.

But recently has invested in products with new and innovative technology that better reflect the needs of current health and safety regulations and the lowering of labour costs, that together provide a much reduced installed cost.

It has been suggested that each year in the UK more than four million holes are excavated in roads and footpaths to repair leaks in services, provide services to new properties and lay new cables and pipes. (This does not include structural work to bridges, street lighting, and cyclical maintenance such as, checking of traffic signals and replacement of street furniture). It’s also very expensive!

In April 2001,the Government introduced reserved powers, allowing local councils to fine utility companies who ‘overstay their welcome’ when digging up roads, up to £2,000 per day for failing to complete the approved roadwork’s within pre-agreed timeframes. In fact last year, in London alone, utility companies were fined more than £3million for over-running on roadwork’s and causing gridlock across the capital.

But despite the Governments attempts to co-ordinate the work of utility companies, a report from the Transport Research Laboratory suggests that traffic disruption and congestion is still continuing to grow. The unnecessary delays from street works cost the travelling public in the UK an estimated £2 billion a year.

We’ve all witnessed the same scenario: Two men and a lorry turn up, put up a barrier, set up the traffic lights, out comes the pneumatic drill, they dig a hole, expose the problem, have a brew and disappear. A day or two later, another couple of men arrive and after they have pumped out the rainwater, removed the ‘take-a-way’ litter and beer cans, start to rectify the problem. After an hour, they too disappear. The next day (if you are lucky) the second two men come back, check the repair and if it’s OK, summon the first two men with the lorry and back fill the hole. The day after another lorry turns up and delivers the asphalt. This they lay, rake and roll out, remove the ‘temporary traffic lights and barriers, hitch up the roller, quick brush round and off they go to their next ‘hole’

If an LV cable repair for traffic signals or streetlights had caused this hypothetical situation, part of the reason that the exercise took so long would be the methods used by cable-jointers who probably still use resin mixtures to effect the repair. That being the case, once the fault in the cable had been exposed, the hole would require extending to allow the cable jointer, room to cut out the damaged cable and effect the repair (because there is now a need to add a new length of cable, two joints are required) and make it ready to accept the ‘shell’ casings.

This is purely due to the fact that you can't re-enter a resin joint without damaging the internal cables. So, the contractor needs to cut the cable out, spend hours and money, locating the same size and configuration of cable and then insert the cable, having now dug a bigger hole to accommodate the additional length of cable and joints and backfill with virgin backfill, not the stuff the first two men had dug out of the original hole.

The cable-jointer would then, after complying with safety procedure, mix the resin in its crucial parts and insert the mixture into the casings, avoiding as he goes, any air bubbles. The resin then takes 24 hours to cure to a point that it can, after testing, be carefully reburied and the road reinstated to accommodate normal traffic. (NB Notice the emphasis on carefully reburied, as often, after a repair has successfully been completed by a fully qualified cable-jointer, an over zealous contractor, in an effort to speed up the job, will drop the new back fill on the repair which in some cases, will crack the hardened resin. This is likely to invite a rapid ingress of water and a couple of weeks after the road has been re-opened, it’s like groundhog day! That same hole appears, in the same place, disrupting the same traffic to allow the same repair to be made all over again!)

With Raytech’s Gel products, all the cable-jointer needs to do is take off the casing, make the repair, and using the same casing, refill with Gel. No need for a bigger hole and cable repaired in minutes. Don’t get me wrong, for the right application; resins are an excellent way of forming tough polymeric cable connections for many electrical and electronic potting and encapsulation applications.

However, they also have a number of downsides. Firstly, resin mixes have a relatively short shelf life and buyers should be made aware of the strict ‘use by’ dates. Secondly, they need to be handled with great care as they can carry a number of exposure hazards arising from the substance itself. Some are combustion products, resulting in the emission of gases. Others are classed as burning products which during mixing, set free a complex combination of gases and airborne particulates, including carbon monoxide, carbon dioxide, nitrogen oxides and other noxious and toxic gases and fumes.

Cable jointers, who handle these products, should avoid inhaling vapors, must wear protective gloves and eye protection and wear personal protection clothing. If contact is made with the skin, washing must be carried out immediately to avoid skin irritation. And if contact is made with the eyes or the product is ingested, Medical advice must be sought.

With the implementation of the REACH directive, (which aims to improve human health) and which became fully operational on 1st June 2008, many of these resin products now run the risk of falling foul of the ruling, which means that cable-jointing methods will have to be substituted for more innovative ones and cable-jointers will have to look seriously at certain products and adopt new and safer methods of cable jointing in the future.

Another reason to change is the time, and therefore money it currently takes to carry out a simple cable joint repair. Now, because new technology allows re-entry within the joint casing, much can be done to speed up the digging and back filling of the ‘hole,’ the current 24hours it takes for the resin filled repair to cure and to test can be totally eliminated.

Whilst considered the perfect solution for filling enclosures & boxes, the totally new, non-toxic ‘Gel-filled Systems’ from Raytech in Italy, are also considered ideal for applications in trunking and pipes, and offers electrical engineers and cable jointers a completely new ‘re-enterable’ option; even after long working periods, compared to current sealing methods.

Two other distinct advantages these new innovative products claim over current ‘resin systems’ are due to the materials softness, which allows the filled components to withstand external shocks without breaking or cracking; making it ideal for extreme installations, even deep underwater, where performance improves with depth of submersion. And secondly, the ability of the ‘Gel’ to cross-link in temperatures as low as -20º completely outperforming resin mixes.

Extremes in daily temperature cycles are easily managed by the soft consistency of the Gel, as opposed to the natural stresses built up in the exothermic curing of resin compounds, which can actually cause breakdown of the joints integrity. Typical installations of these joints are directly buried, in ducts or traps, fully submerged at any depth (e.g. submersible pumps), directly exposed to UV and weather agents, in tunnels or at the base of columns for street lighting, bollards and traffic signals.

Offering speed of installation, the gel-system can be used without the use of particular tools like torches or other specialist equipment thus reducing the skill factor of the operator and the installation time.

The system, being absolutely non-toxic, due to the chemical characteristics of the gel, and totally chemically inert, it totally complies with the REACH directive and therefore negates the use of specialist health & safety precautions that would be required with some resin systems.

To date, Raytech ‘Magic-Gel Systems have been installed extensively throughout the world, in Northern, cold countries as well as in Middle Eastern, hot regions; literally millions of pieces have been installed for connecting distribution cables, public lighting in streets or tunnels and industrial or civil purposes. It is completely non-toxic, sets in less than 10 minutes, is re-enterable, offers greater than IP68 rating and has no shelf life!

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