Steel Structure used as Lightning Protection System (LPS)

The design of a Lightning Protection System (LPS) should be technically and economically optimized.

Clause 4.2 Design of the LPS in IEC 62305-3 - Protection against lightning Part 3: Physical damage to structures and life hazard states that design optimization could be achieved if design and construction of the LPS are coordinated with the design and construction of the structure to be protected.

Can the steelworks of the protected structure be used as parts of the LPS? The answer to this question is YES compliant to some conditions.

1. Electrical Continuous Steelworks
Steelworks within reinforced concrete structures is considered to be electrically continuous provided that the major part of interconnections of vertical and horizontal bars are welded or otherwise securely connected. Connections of vertical bars shall be welded, clamped or overlapped a minimum of 20 times their diameters and bound or otherwise securely connected.
Welded Joints (suitable for lightning current and EMC purposes)
Clamped Joints (suitable for lightning current and EMC purposes)
Bound Joints (suitable for lightning current and EMC purposes)
Lashed Joints (suitable for EMC purposes only)
2. Resistance not be greater than 0.2 ohms
Clause 4.3 Continuity of steelworks in reinforced concrete structures in IEC 62305-3 - Protection against lightning Part 3: Physical damage to structures and life hazard states that the electrical continuity of the reinforcing bars shall be determined by electrical testing between the uppermost part and ground level. The overall electrical resistance should not be greater than 0.2 ohms, measured using test equipment suitable for this purpose.

The connection to outside components of the lightning protection system should be established by a reinforcement rod brought out through the concrete at a designated location or by a connecting rod or ground plate passing through the concrete which is welded or clamped to the reinforcing rods. The most commonly used method for this is the earthing boss or the earthing plate.

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A Filipino Engineer, Registered Professional Engineer of Queensland (RPEQ) - Australia and Professional Electrical Engineer (PEE) - Philippines with extensive experience in concept select, front-end engineering, HV & LV detail design, construction and commissioning of Hazardous and Non-Hazardous Area electrical installations in water and waste water pipeline and pumping facilities, offshore platforms, hydrocarbon process plants and pipelines including related facilities. Hazardous area classification and design certification (UEENEEM015B, UEENEEM016B, UEENEEM017B).