What are lightning protection levels (LPL)?

The different Lightning Protection Levels (LPL), only refer to the type I arrester and its impulse current 10/350 µs. A distinction is made between lightning protection levels I, II and III/IV, with the probability of lightning damage increasing from lightning protection level I to lightning protection level III/IV.

Lightning protection level I

Lightning protection level I

Lightning impulse current [Iimp]: 200 kA

Effectiveness: 98%

Lightning protection level II

Lightning protection level II

Lightning impulse current [Iimp]: 150 kA

Effectiveness: 95%

Lightning protection level III/IV

Lightning protection level III/IV

Lightning impulse current [Iimp]: 100 kA

Effectiveness: 88% / 81%

Lightning protection level I

Lightning protection level I

A pulse of 200 kA hits the external lightning protection system directly and is conducted half into the earth and half into the electrically conductive parts of the system. Depending on the number of conductors, the current is divided into 25 kA (4-conductor system) or 20 kA (5-conductor system) per conductor.

Examples of lightning protection level I are:

  • Petrochemical facilities (Ex-zones)
  • Explosive material depots

Lightning protection level II

Lightning protection level II

A pulse of 150 kA hits the external lightning protection system directly and is conducted half into the earth and half into the electrically conductive parts of the system. Depending on the number of conductors, the current is divided into 19 kA (4-conductor system) or 15 kA (5-conductor system) per conductor.

Examples of lightning protection level II are:

  • Telecommunications towers
  • Parts of hospitals
  • Freight warehouse with fire alarm systems

Lightning protection level III/IV

Lightning protection level III/IV

A pulse of 100 kA hits the external lightning protection system directly and is conducted half into the earth and half into the electrically conductive parts of the system. A current of 12.5 kA per conductor is assumed for both a 4-wire system and a 5-wire system.

Lightning protection level III/IV covers approx. 80% of all applications, e.g:

  • Buildings
  • Residential homes
  • Administrative buildings
  • Industrial plants

Example calculation

Flash pulse calculation

This example shows how to select the correct type I arrester.

Assumption:
It is an application with external lightning protection.

  • Lightning protection level III: 100 kA
  • Mains voltage: 230 / 400 V AC
  • Mains system type: TN-C-S (L1, L2, L3, N, PE)

Calculation:

  • A direct lightning strike occurs with 100 kA.
  • 50% (50 kA) of this is conducted directly to earth.
  • 50% (50 kA) of this is fed into the building.

Flash pulse formula

Parameters for lightning and surge protection:

  • Limp = 50 kA / 4 arresters = 12.5 kA
  • Un = 230 V = Uc = 300 V

Product recommendation:

VPU AC I 4 R 300/12.5 LH

VPU AC I 3+1 R 300/12.5 LH

VPU AC I 3+1 R 300/12.5 LCF

Risk-oriented lightning protection

The publication ‘Risikoorientierter Blitz- und Überspannungsschutz ’ from the German Insurance Association (GDV) offers help in assessing the risk of damage caused by lightning and surges.

The document describes various objects and their assignment to the lightning protection levels. Normally, a complex calculation is required to determine this classification. The document helps to assess a quick classification, is only valid in Germany and is only a recommendation. It does not release the user from a risk assessment.

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