Basic of External Lightning Protection System (LPS)-(Part-4)

BASIC OF EXTERNAL LIGHTNING PROTECTION SYSTEM (LPS)-(PART-4)

October 1, 2024 Leave a comment

MATERIAL COMBINATIONS AND DIMENSIONS

Required to use galvanically compatible metals in lightning protection system components and surface materials on which the components are mounted. For example, do not connect copper to aluminum. * Do not use together metals that are not galvanically compatible. Bad matching accelerates their corrosion in the presence of moisture. * With aluminum conductors, use only connection devices designed for aluminum. Make sure to use the right fastening torque.

Different Contact Material

Material

Suitable Contact Material

Copper

Nickel /Brass / Tin / Lead / Stainless steel / Monel (nickel–copper alloy) Aluminum

Magnesium / Zinc / Galvanized steel / Stainless steel / Lead / Wrought iron / Galvalume (an aluminum-coated sheet steel product)

LPS MATERIAL

LPS Materials and Conditions of Use

Table-5 (IEC 62305-3)

Material Use Corrosion In Open Air In Earth In Concrete Resistance Increased by May be destroyed by Galvanic Coupling with Copper Solid Solid Solid Good in many environments Sulphur compounds – Stranded Stranded Stranded – Organic materials – – As coating As coating – – – Hot galvanized steel123 Solid Solid Solid Acceptable in air, in concrete, and in benign soil High chlorides content Copper Stranded 4 – Stranded 4 – – – Steel with electro-deposited copper Solid Solid Solid Good in many environments Sulphur compounds – Stainless steel Solid Solid Solid Good in many environments High chlorides content Stranded Stranded Stranded – – – Aluminum Solid Unsuitable Unsuitable Good in atmospheres containing low concentration of Sulphur and chloride Alkaline solutions Copper Stranded – – – – – Lead 5 Solid Solid Unsuitable Good in atmospheres with high concentration of sulphates Acid soils Copper As coating As coating – – – Stainless steel

MATERIAL DIMENSIONS

Several lightning protection system codes and standards define minimum dimensions for the components of a grounding system. These standards are designed to protect buildings and other inhabited or otherwise critical facilities. * Practical minimums are based on field experience and indicate what is needed to protect the installed equipment in a cost-effective way during the foreseeable technical lifetime, typically a few decades, taking into account local regulations. To ensure proper operation of the grounding system, periodic inspection and maintenance is needed

MINIMUM DIMENSIONS OF EARTH ELECTRODE AS PER IEC 623053

Table 1 and Table 2 are based on standard IEC 62305-3 Ed 2. The tables list minimum dimensions for the lightning protection system equipment. * The following table lists the different materials and shapes that are used in air terminals, down conductors, and ground electrodes, including the cross-sectional area.

Minimum Dimensions of Earth Electrodes

Table-7, IEC-62305-3

Material Configuration Dimensions Earth Rod Diameter Earth Conductor Earth Plate Copper, Tin-plated copper Stranded – 50 Sq.mm (8 mm) – Solid round 15 mm 50 Sq.mm (8 mm) – Solid tape – 50 Sq.mm (8 mm) – Pipe 20 mm – – Solid plate – – 500 × 500 mm Lattice plate – – 600 × 600 mm Hot-dipped galvanized steel Solid round 14 mm 78 Sq.mm (9.96 mm) – Pipe 25 mm – – Solid tape – 90 Sq.mm (10.7 mm) – Solid plate – – 500 × 500 mm Lattice plate – – 600 × 600 mm Profile * – – Bare steel (Shall be embedded in concrete for a minimum depth of 50 mm.) Stranded – 70 Sq.mm (9.4 mm) – Solid round – 78 Sq.mm (9.96 mm) – Solid tape 75 Sq.mm (9.72 mm) Copper coated steel Solid round 14 mm 50 Sq.mm (8 mm) Solid tape 90 Sq.mm (10.7 mm) Stainless steel Solid round 15 mm 78 Sq.mm (9.96 mm) Solid tape 100 Sq.mm (11.28 mm) Mechanical and electrical characteristics as well as corrosion resistance properties shall meet the requirements of the future IEC 62561 series. In case of a type B arrangement foundation earthing system, the earth electrode shall be correctly connected at least every 5 m with the reinforcement steel. * Different profiles are permitted with a cross-section of 290 mm2 and a minimum thickness of 3 mm, e.g. cross profile.

MINIMUM CROSS-SECTIONAL AREA OF AIR-TERMINATION CONDUCTORS

Minimum Cross-sectional Area of Air-termination Conductors

Table 6 (IEC 62305-3)

Material Configuration Cross-sectional Area Comments Copper, tin-plated copper Solid tape 50 Sq.mm / 8mm * 2 mm min. thickness Solid round1 50 Sq.mm / 8mm * 8 mm diameter Stranded 1 50 Sq.mm / 8mm * 1.7 mm min. dia of each strand Solid round*** 176 Sq.mm /15mm 16 mm diameter Aluminum Solid tape 70 Sq.mm* 3 mm min. thickness Solid round 50 Sq.mm / 8mm * 8 mm diameter Stranded 50 Sq.mm / 8mm * 1.7 mm min. dia of each strand Aluminum alloy Solid tape 50 Sq.mm / 8mm * 2.5 mm min. thickness Solid round 50 Sq.mm / 8mm * 8 mm diameter Stranded 50 Sq.mm / 8mm * 1.7 mm min. dia of each stra…