Protection at your fingertips

Apr 19, 2012 | UPS & Standby Power

Protection at your fingertips

Weidmüller offer a range of industry solutions that can help protect against overvoltages in order to ensure the safety of critical electrical systems

Any switching operation, fault initiation or interruption is followed by a transient phenomenon in which an overvoltage can occur. Common causes can include power grid quality issues, downed lines or faulty wiring. Surges can also occur through natural causes such as lightning strikes. These can all cause massive disruption, degradation, sparking or flashover. These can destroy any unprotected electronic system, resulting in systems failure, corrupted data, unnecessary down-time, health and safety issues, damaged reputations and can even be life threatening.

In July 2011, the Institution of Engineering and Technology (IET) and the British Standards Institution (BSI) jointly published important changes to The IET Wiring Regulations, 17th Edition, BS 7671:2008 incorporating Amendment No.1, 2011. This set out the national standard to which all new electrical installations must comply, and they came into effect on 1st January 2012.

The changes in the regulations were in part due to the complexity of modern installations and the resulting increase in client expectations regarding the reliability and safety of the installations. This has meant new considerations for those involved in protecting businesses against the potential effects of transient overvoltages, along with the maintenance, installation and/or design of electrical installations or wiring in buildings.

The new Section 534: Devices for protection against overvoltages, is a section that comprises a collation of information that can be found in:

l BS EN 7671:2008 Section 443.

l BS EN 60664-1 Insulation Co-ordination.

l BS EN 62305-4 Protection of Electronic Systems within Structures.

l BS EN 61643 Parts 12 & 22: Power, Data, Telecoms and Signal Surge Protection.

The standard has been designed to ensure that all competent parties adhere to, and implement, lightning and surge protection strategies, within electrical systems. It also lays out selection and erection guidelines for installations.

Weidmüller Class 1 solutions

The installation is protected from direct lightning strikes by using lightning current or equipotential bonding surge protection devices (SPDs). Lightning current or equipotential bonding SPDs are designed to prevent dangerous sparking which can occur between the structural LPS and electrical services. This presents a potential fire hazard and risk from electric shock.

Class I SPDs should be installed as close to the point of entry to the building as possible when there is an external lightning protection system in place.

Weidmüller Class II solutions

The installation can be protected from indirect lightning strikes by using Class II SPDs. If there is no external LPS required, Class II devices are the first level of protection. Class II SPDs are designed to protect electrical and electronic equipment from the secondary effects of an indirect lightning strike and against switching transients such as those caused by motors and HVAC equipment.

If a Class I SPD is present then Class II SPDs should be installed at sub-distribution boards and at equipment level. Although, as previously mentioned, these devices can also be used at point of entry should no external protection be needed.

Weidmüller Class III solutions

These SPDs are designed to protect delicate and system critical electrical and electronic equipment from the effects of damaging switching transients.

Class III SPDs give the best protection when used in a co-ordinated system and should have a Class II device installed upstream – they can be installed at the sub-distribution board or equipment level.

CPD seminars

Weidmüller UK is now certified by the Chartered Institution of Building services Engineers (CIBSE) as a CPD Course Provider. This means that the company is now able to offer CIBSE accredited Continuous Professional Development (CPD) seminars on its surge solutions, which means that these events can contribute towards the CIBSE CPD requirement needed to keep skills and knowledge up to date and ensure electrical work is completed safely, legally and effectively.

Weidmüller’s CPD seminars are aimed at providing the critical and pertinent facts on changes in legislation, and the impact they may have, along with effective approaches to simplify implementation and ways of reducing overall labour and maintenance costs. The company aim to clarify and ease selection of products to meet the new standards with its own training seminars and comprehensive product portfolio, designed to help ensure installations or projects meet all aspects of these new changes.

This course discusses Surge Protection and in particular provides an understanding of BS7671:2008 Amendment 1. The main aim of the course is to provide the delegate with enough information to confidently select their own or interface with end customers with respect to the selection of the correct surge protection devices to suit a range of applications.


T: 0845 094 2006