Lightning Arrester - BS 7671 Detailed Answers

A lightning arrester also known as a surge arrester or lightning rod is a crucial component in electrical installations to protect against the damaging effects of lightning strikes. Here's a detailed overview according to BS 7671:

1. Purpose of Lightning Arrester:

The primary purpose of a lightning arrester is to safeguard electrical systems and equipment from the destructive impact of lightning. Key objectives include:

• Redirecting Lightning: Lightning arresters provide a designated and low-resistance path for lightning strikes redirecting the electrical energy safely to the ground.
• Preventing Equipment Damage: By diverting lightning currents away from sensitive equipment lightning arresters help prevent damage to appliances devices and the overall electrical system.
• Protecting Structures: Lightning arresters are often installed on buildings and structures to minimize the risk of structural damage caused by lightning strikes.
• Ensuring Safety: Protecting against lightning-related electrical surges enhances overall electrical safety for both the property and its occupants.

2. BS 7671 Compliance:

BS 7671 also known as the IET Wiring Regulations outlines standards and requirements for electrical installations in the UK. Lightning arresters must comply with these regulations to ensure their effectiveness and safety:

• Installation Standards: Lightning arresters should be installed following the guidelines set out in BS 7671. This includes proper positioning grounding and connection to the electrical system.
• Material and Construction: The construction and materials used in lightning arresters must meet the specifications outlined in BS 7671 to ensure durability and reliability.
• Integration with Earthing System: Lightning arresters should be integrated into the overall earthing system of the installation to provide a low-resistance path for lightning currents.
• Surge Protection Devices (SPDs): Lightning arresters are often considered a type of surge protection device. Compliance with BS 7671 involves proper selection and installation of SPDs to protect against transient overvoltages.

3. Professional Installation:

Installation of lightning arresters should be carried out by qualified professionals with knowledge of BS 7671. Key installation considerations include:

• Location: Lightning arresters should be strategically located to provide effective protection. This may involve positioning them at high points on structures or near critical electrical equipment.
• Connection: Proper connection to the earthing system is essential for the efficient operation of the lightning arrester. This includes using appropriate conductors and ensuring secure connections.
• Inspection and Maintenance: Regular inspection and maintenance are crucial to ensure the continued effectiveness of lightning arresters. Professionals should follow the maintenance guidelines outlined in BS 7671.

Adhering to the standards set by BS 7671 ensures that lightning arresters provide reliable protection against the unpredictable and potentially damaging effects of lightning strikes on electrical installations.