Objective:
minimise lightning electromagnetic effects (LEMP) on electrical & electronic systems. Defines Lightning Protection Zones (LPZ), coordinated SPDs, shielding, and bonding. Adopted in Malaysia as MS IEC 62305.
Part 4
4 zones
3 SPD types
MS IEC 62305
Scope
What IEC 62305-4 covers
Six interconnected measures — all required together. No single measure provides adequate protection in isolation.
Assess and reduce the electromagnetic threat from all four lightning source types — direct strikes, near-structure, and conducted surges on incoming service lines.
Selection, coordination, and installation of SPDs at each LPZ boundary to progressively clamp surge voltages to a safe level for the next zone inward.
Equipotential bonding networks at every LPZ boundary bar, connecting all metallic services — pipes, cable screens, structural steel — to a common reference.
Spatial shielding (Faraday cage), cable screening, and routing rules that reduce the electromagnetic field strength reaching sensitive electronics inside each zone.
The LPZ framework divides a structure into zones of progressively lower threat. All other measures are implemented at zone boundaries, not inside zones.
Systematic sequencing of Type 1, 2, and 3 SPDs — each device clamps the surge to a safe level for the next one downstream. Not interchangeable by type.
LPZ concept
Lightning Protection Zones explained
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Lightning Protection Zones
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Description
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LPZ 0A
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Direct lightning exposure
The unprotected exterior — rooftop, open ground, exposed conductors. Full lightning current and full electromagnetic threat. The external LPS (IEC 62305-3) operates here. |
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LPZ 0B
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Partial exposure — no direct strike
Within the protection angle of the external LPS, so a direct strike is unlikely — but the full LEMP threat from nearby and remote strikes propagates freely. Type 1 SPD required at the 0B→1 boundary. |
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LPZ 1
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Direct lightning exposure
The unprotected exterior — rooftop, open ground, exposed conductors. Full lightning current and full electromagnetic threat. The external LPS (IEC 62305-3) operates here. |
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LPZ 2
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Direct lightning exposure
The unprotected exterior — rooftop, open ground, exposed conductors. Full lightning current and full electromagnetic threat. The external LPS (IEC 62305-3) operates here. |
LPZ 0A
- Building roof & exterior
- Open land, antenna masts
- Outdoor switchgear
LPZ 0B
- Under air terminal coverage
- Covered walkways (with LPS)
- Atria with LPS above
LPZ 1
- General building interior
- Main distribution board
- Cable risers, plant rooms
LPZ 2
- Data centre server halls
- UPS & battery rooms
- SCADA / control rooms
Surge Protection Devices
SPD coordination
Three SPD types must be installed in sequence across LPZ boundaries. Each clamps the surge to a safe level for the next device downstream — no type can substitute for another.
Lightning current arrester
Main distribution board (MDB)
LPZ 0 → 1 boundary
Test: 10/350 µs (Iimp)
Surge arrester
Sub-distribution boards
LPZ 1 → 2 boundary
Test: 8/20 µs (In)
(Iimp)
Point-of-use protector
At equipment (within 5 m)
LPZ 2 → device
Test: 1.2/50 µs + 8/20 µs
- Type 1 handles the full lightning current impulse. Installing a Type 3 at the main board will fail — its energy capacity is far too low.
- Type 3 at equipment alone provides no protection without upstream Type 1 and Type 2 already in place to absorb the bulk of the energy.
- When Type 1 and Type 2 are less than 10 m apart, a coordination element is required to ensure the upstream device discharges first.
- Coordination applies to all services crossing LPZ boundaries — power lines, data cables, telecom, and any metallic conductor entering the zone.
Standards comparison
IEC 62305-3 vs IEC 62305-4
Complementary, not alternatives — both are required for complete lightning protection of any facility with critical electronics.
Protects the building from direct strikes
- Air terminals, down conductors, earth termination network
- Prevents fire, structural damage, and shock from direct strikes
- Protection level defined by LPL I–IV (from IEC 62305-2 risk assessment)
- Passive — activates only when a direct strike occurs
- Output: LPS layout drawings, earthing resistance targets, material specs
Protects what's inside the building
- SPDs, shielding, equipotential bonding, LPZs, cable routing rules
- Prevents electronics damage from conducted surges and radiated LEMP
- Protection defined by LPZ 0A → 0B → 1 → 2
- Continuous — protects against all nearby and distant strikes
- Output: LPZ plan, SPD schedule, bonding layout, shielding specification
Malaysia context
IEC 62305-4 compliance in Malaysia
In Malaysia, IEC 62305 is adopted as MS IEC 62305, recognised by JKR and SIRIM. IEC 62305-4 compliance — LPZ design, SPD coordination, and bonding — is required for data centre Tier certification, JKR submissions, and facilities seeking international consultant approval.
Malaysia’s ground flash density in Johor Bahru, the Klang Valley, and Penang is among the highest in the world — Source: MetMalaysia / TNB lightning data — making LEMP a near-daily risk for facilities with unprotected electronics.
Tokai Engineering provides complete IEC 62305-4 compliant surge protection design and installation — LPZ analysis, SPD selection and coordination, bonding network design, and commissioning documentation — across Malaysia since 1991.
Facilities requiring IEC 62305-4 in Malaysia
FAQ
Frequently asked questions
What is IEC 62305-4?
IEC 62305-4 (Protection Against Lightning — Part 4) is the standard for protecting electrical and electronic systems from LEMP. It defines LPZs, SPD coordination, shielding, and bonding. Adopted in Malaysia as MS IEC 62305, recognised by JKR and SIRIM.
What are Lightning Protection Zones?
LPZs are concentric zones from LPZ 0A (direct lightning exposure) through LPZ 0B, LPZ 1, to LPZ 2 (highly protected). Each boundary is where SPDs, bonding, and shielding are applied to progressively attenuate the LEMP threat.
What is LEMP?
LEMP (Lightning Electromagnetic Pulse) is the electromagnetic effect of a lightning discharge — conducted surges on power and data lines, magnetic field induction in cable loops, and radiated electromagnetic fields. LEMP can destroy sensitive electronics without a direct strike. Malaysia records 180–260 thunderstorm days per year (MetMalaysia).
What is the difference between IEC 62305-3 and IEC 62305-4?
IEC 62305-3 covers the external LPS — air terminals, down conductors, and earthing for the physical structure. IEC 62305-4 covers the internal LEMP protection — LPZs, SPDs, shielding, and bonding for electronics. Both are required together.
What does SPD coordination mean?
Coordinated SPDs means installing Type 1 (main board), Type 2 (sub-boards), and Type 3 (at equipment) in sequence — each clamps the residual surge for the next device. One type alone is not a coordinated system.
Is IEC 62305-4 required for data centres in Malaysia?
Yes. Hyperscale data centres in Johor Bahru and Selangor require IEC 62305-4 compliant LEMP protection for Tier III/IV certification, international consultant approval, and JKR submission.
