Quality matters

Why is the quality of materials used in electrical installations so important?

HT: You first need to look at the effect of using low-grade materials. The first impact is on safety. In November 1987, the Kings Cross disaster hit the headlines as the greatest loss of life on the Underground in almost a decade. In total 31 people died, but what many don’t realise is that fumes from melting fixtures, ties and cables were a key contributor to the number of fatalities.

Following the tragedy, new requirements were introduced for zero halogen (HF) and limited fire hazard (LFH) products to be used in public buildings. Fixings were also required to have a resistance to burning (V0 rated materials). Products which meet HF, LFH and V0 standards will have been tested for toxic smoke generation, flammability and flame propagation to reassure specifiers that, should a fire occur, the products they use will not contribute to fatalities.

The second impact is on the longevity of the installation, which is also linked to safety. Poor quality materials used in cables and cable management products are often made from second grade nylon and can become brittle when exposed to the air during use. If the product becomes brittle it will break, which can cause an installation to fail completely – that could be potentially life threatening if the installation is in a public place.

Another important consideration is liability. In a society which is ever more driven by ‘blame culture’, traceability is increasingly important. Should poor quality products be to blame for an accident or fatality, the consequences will be serious, as ultimately, responsibility stops at the contractor, rather than at a product which was ill-chosen for the application.

You are calling for a more ‘holistic view’ for the specification of electrical installations – tell us more?

HT: Specifiers need to look at electrical installations as a whole. We have seen installations where a contractor has specified premium cables but has managed those cables with low grade fixings. All the time and effort has gone into choosing the correct cabling which is HF and V0 rated, but the cable management products have been selected on price or availability. It’s like laying railway tracks with drawing pins.

By taking a holistic view of an installation, you are able to see the wider picture. It is not just the larger elements such as the cables and enclosures that should be specified to the highest grade to ensure a safe and durable installation. By looking at the finer details and ensuring that fixtures and fixings are manufactured to the same standards, using the same materials as the cables, specifiers can confidently guarantee the quality of their work.

Does quality vary much from product to product?

HT: Very much so. Manufacturers such as HellermannTyton use the latest techniques to ensure that products reach contractors in peak condition and offer superior performance. As with all premium brands, our cable ties are made from pure, first grade nylon that gives our products set tensile strengths which can be used to calculate the right tie for every application. Moisture is taken out of the plastic during the manufacturing process and is added back in at the packaging stage – this ensures the plastic has the correct balance of properties and is strong, as well as flexible.

We urge contractors to specify premium cables and cable management products to ensure that future installations are safe.

There are manufacturers who supply to the UK market who use substandard second grade nylon, which does not have the same integrity as first grade nylon. This material can incorporate reground materials and high amounts of water so that the product appears flexible, but once the excess water evaporates during exposure to air, the material becomes brittle and breaks.

To look at a premium cable tie and a lower grade cable tie, the visual difference will be minimal. This is why we recommend that specifiers verify the quality of a cable tie by checking whether it has achieved the Milspec 23910 industry standard. Cable ties achieving this standard should be moulded with a number as well as the manufacturer’s company name or logo.

You have conducted some research into the difference in quality between cable ties. What were your findings?

HT: We conducted a series of tests on cable ties from our own range and compared their performance with ties from other premium manufacturers, as well as cheaper alternatives. The first test was to compare the same cable tie (300 mm x 4.8 mm or nearest equivalent) under different temperature conditions (20°C, 85°C and -40°C) to measure the average maximum force of the product.

At 20°C, performance varied from 542·6 N for the best performing tie to 313·7 N for the poorest performing product. At 85°C, the variance was much more pronounced with the leading tie able to sustain a mean force of 616·2 N and the least just 95·2 N – a difference of 521 N. At -40°C, the performance variable was much the same as at 20°C, with the leading tie able to withstand a mean force of 505·9 N and the least 279 N.

Next we compared loom retention for a range of ties from a variety of manufacturers. The three worst cable ties failed 100%, 60% and 40% respectively of the tests carried out on their loom retention. Should these cable ties have been used in an application, the contractor would be going back to make repairs soon after leaving the site or risk the integrity of the remainder of the installation – and public safety.

At our manufacturing plant in Manchester, we have a dedicated team of quality engineers who carried out the quality testing. They concluded that the inferior performance of some makes of cable tie suggested that not only was substandard nylon being used, but that the material was being ground with other materials such as old carpet tiles and plastic bottles. We are obviously very concerned about these findings and would urge contractors to specify premium cables and cable management products to ensure that future electrical installations are safe.

Is there anything else that contractors can do to ensure they are using premium quality ties?

HT: We encourage contractors to ensure that the products do meet the specifications they claim. It is always prudent to ensure the products incorporate the company logo and a moulding number but not to rely on this fact alone. By using reputable manufacturers that know poor quality electrical accessories and especially cable management products can prove fatal, you can be reassured that the products you are buying are of a high quality.