Electrical Contracting News (ECN) Cable & Cable Management 2017 | Page 18

DETA ELECTRICAL KNOWLEDGE IS STRENGTH Robert Tucker, product manager at Deta Electrical, explores the various levels of specification within the BS EN 61386 standard. As he explains, not all conduit tube is equal. S teel conduit tube and fittings have been used for over a century as part of cable management systems for wiring. This durable and adaptable solution is used in various markets around the world. When designing cable management systems, various aspects need to be considered, including the location, whether it will be used indoors, outside, or in a clean room, its mechanical strength, and its ability to provide an effective bonding path. It is all too easy, when buying conduit tube and fittings, just to order galvanised conduit, but how do specifiers, installers and buyers know they are getting a product that will meet their specific requirements? Levels of specification The current safety standard for conduit tube is BS EN 61386, and while it’s possible to specify tube to this standard, it’s important to consider the various levels of specification within the standard. This harmonised standard lays out the performance requirements for conduit tube, such as its mechanical strength, bonding effectiveness and resistance to corrosion. Each criterion has several classification levels. The resistance to compression criteria, for example, has a classification range from one: Very light Location plays a big part in determining requirements for a cable management system. with a compression force of 125N, up to five: Very heavy with a compression force of 4,000N. Clearly, there is a wide range, with a varying factor of over thirty. It is because of these different classification levels that if conduit is specified by the standard alone, you could receive a product that will not meet your requirements. Independent testing Deta TTE conduit tube is tested and certified by BSI to BS EN 61386. 18 | August 2017 Cable & Cable Management Independent testing will confirm that the product meets the standard, while the report will confirm which classification levels it meets. Deta TTE conduit tube is tested and certified by BSI to BS EN 61386, confirming that it exceeds the most demanding classification five rating for resistance to compression, resistance to impact and tensile strength. It is also tested to confirm compliance with bending, threading, electrical bonding and ingress protection and achieves the highest class four resistance to corrosion classification. Corrosion resistance is particularly important, since the term ‘galvanised’ is applied to a variety of different zinc coatings used to protect iron or steel. BS EN 61386 includes several different corrosion classifications, the most demanding being class four, which requires both internal and external surfaces to pass the heavy protection corrosion test. To achieve this rating, Deta TTE conduit tube is galvanised on a dedicated plant using the optimum zinc coating to provide an extended corrosion-free life, while also allowing the conduit to be formed on-site without damage to the protective coating. The final stage of the process employs a steam blast to ensure that the bore of the conduit is smooth and free of debris that could damage cable insulation. Every length of tube is marked with the Deta TTE brand name, the BS EN 61386 standard number and is clearly marked with a ‘Class 4’ classification. For further information visit: www.detaelectrical.co.uk.