MS IEC 62305 Compliant Lightning Protection Solutions

[edit] Introduction

MS IEC 62305 is the Malaysian adoption of the IEC 62305 series of standards for protection against lightning. The series provides principles and requirements for assessing lightning risk and for designing, installing, inspecting and maintaining lightning protection systems (LPS) for buildings and other structures.

Lightning protection is intended to reduce the risk of physical damage to structures, injury to people and damage to electrical and electronic systems resulting from lightning. Protection measures may include an external lightning protection system, equipotential bonding, earthing and surge protection measures. The appropriate measures depend on the characteristics and use of the structure, the consequences of lightning damage and the results of a lightning risk assessment.

[edit] MS IEC 62305 and lightning protection

[edit] Structure of the standard

The MS IEC 62305 series is based on the IEC 62305 series and addresses different aspects of lightning protection. Its principal parts cover general principles, risk management, physical damage to structures and life hazard, and protection of electrical and electronic systems within structures.

Risk assessment is an important part of the approach. It considers the likelihood and consequences of lightning-related events and allows appropriate protection measures to be selected. Protection is not necessarily required to the same extent for every building; the level and type of protection should reflect the assessed risk and the requirements applicable to the particular structure.

Compliance with a standard should not be confused with statutory approval. Whether a lightning protection system is required by legislation or building regulations depends on the applicable legal and regulatory framework. MS IEC 62305 provides a technical basis for design and implementation where the standard is applicable or specified.

[edit] Components of a lightning protection system

A lightning protection system normally comprises an arrangement of conductors and components designed to provide a controlled path for lightning current and to reduce the resulting risks. Depending on the design, this can include:

• air-termination systems;
• down-conductors;
• earth-termination systems;
• bonding conductors and equipotential bonding arrangements;
• isolating or separation measures where required; and
• surge protective devices (SPDs) for electrical and electronic systems.

An air-termination system provides defined points or surfaces at which a lightning discharge can terminate. It does not prevent lightning strikes or necessarily attract lightning. Its purpose is to provide a suitable interception arrangement and conduct the resulting current safely through the lightning protection system.

Down-conductors provide paths between the air-termination system and the earth-termination system. Their arrangement is important in controlling the current path, reducing the likelihood of dangerous sparking and limiting electromagnetic effects.

The earth-termination system provides a means of dispersing lightning current into the ground. Its design is considered together with the rest of the lightning protection system rather than being assessed solely by its earth resistance value.

Equipotential bonding can reduce dangerous potential differences between conductive parts of a structure during a lightning event. Electrical and metallic services entering a building may also require appropriate bonding and surge protection measures.

SPDs are used to limit transient overvoltages and divert surge currents associated with lightning and other electrical events. Their selection and installation should be coordinated with the electrical installation and the lightning protection system.

[edit] Design, installation and maintenance

Lightning protection should be considered during the design of a building or structure because the arrangement of structural, electrical and mechanical systems can affect the practicality and effectiveness of the completed system. The design should take account of the building geometry, materials, services, occupants, contents, electrical and electronic systems and the consequences of a lightning event.

Where an LPS is required, its components should be selected and installed so that they provide electrically continuous and mechanically suitable current paths. Particular attention may be required where conductors pass close to conductive services or other metallic components, because differences in electrical potential during a lightning event can result in side-flashing or dangerous sparking. Separation distances, bonding and other measures should therefore be considered as part of the overall design.

Installation should follow the design and the requirements of the applicable parts of MS IEC 62305. Components should be appropriately secured and protected against mechanical damage and corrosion, and connections should provide reliable electrical continuity.

Inspection and maintenance are necessary because the condition of a lightning protection system can change during the life of a building. Conductors and connections may be damaged, corroded or altered during building work, while extensions, new services, roof modifications and changes to electrical installations can affect the original design. Periodic inspection should therefore consider the condition and continuity of the system and whether alterations to the building have affected its suitability.

The frequency and extent of inspection should be determined by the applicable requirements, the characteristics of the installation and the level of risk. Where defects or significant alterations are identified, assessment and remedial work should be undertaken by appropriately competent persons.

[edit] Risk management and protection of electrical systems

The objective of lightning risk management is to determine whether protection measures are necessary and, where they are, what measures provide an appropriate reduction in risk. The assessment can consider risks including loss of human life, loss of service to the public, loss of cultural heritage and economic loss, depending on the circumstances and the applicable standard.

Protection against direct lightning effects is only part of the overall strategy. Lightning can also produce transient overvoltages and electromagnetic effects that may damage electrical and electronic equipment without a direct strike to the equipment itself. Buildings containing sensitive electronic systems may therefore require coordinated measures including SPDs, bonding and appropriate routing and separation of services.

A lightning protection system should also be coordinated with other building systems. Metallic services, electrical installations, communications systems, photovoltaic installations and other conductive components can provide pathways for lightning current or transient energy. Changes to these systems after completion should be assessed to determine whether the original lightning protection arrangements remain appropriate.

[edit] Related articles on Designing Buildings

• Lightning protection system
• Lightning conductor
• Earthing
• Electrical safety
• Fire safety design
• Risk in building design and construction
• Building services
• Concept services design
• Power surge