Lightning Protection Zones (LPZ)

The featured image of the article 'Lightning protection zones', a cartoon image of a factory in rain and lightning.

Concept of Lightning Protection Zone

The advanced electrical and the electronic devices which are sensitive to the surges originating from the direct or indirect lightning stroke are becoming increasingly popular in different types of sector ranging from Residential Buildings to Hospitals to Data Centers. The economic losses happening due to the damage of these instruments demands a permanent solution to this elevated problem. The protection of these electrical and electronic components against the Lightning Electro-magnetic Pulse (LEMP) is based on the Lightning Protection Zone (LPZ) concept.

The picture shows the division of the structure into different zones.
According to this principle, the structure can be divided into different zones based on the risk levels posed by the Lightning Electro-magnetic Pulse. This gives the freedom to choose the Lightning Protection Zone based on the type, sensitivity and the insulation parameters of the electronic systems.
Depending on the number, type and withstand level of the equipment to be protected, suitable LPZ can be defined. These may include small local zones (e.g. equipment enclosures) or large integral zones (e.g. the whole structure).

Lightning Protection Zone (LPZ):

With respect to the threats due to the Lightning, the Lightning Protection Zones can be divided into the following categories as defined in IS/IEC 62305 – 1:

Outer Zone:

It is the zone that is closest to the direct lightning strike point and is designed to withstand the highest level of lightning current and associated transient over voltages
LPZ 0: It is the first zone in the LPS that lightning current may encounter as it enters a building or structure. LPZ 0 is subdivided into:


LPZ 0A: 
It is the unprotected area and they are exposed to direct lightning strikes. Hence the components are exposed to full lightning impulse surge currents.

These zone is protected against direct lightning strikes by air terminals. The internal systems will be subjected to partial lightning surge currents.

Inner Zone:

The Inner Zone is the area inside the structure protected.

LPZ 1: 

It is the zone inside the structure where the magnitude of surge current is reduced due to multiple parallel paths and isolating interfaces and/or by installing SPDs on the main distribution boards at the boundary. Spatial shielding shall be used to reduce electromagnetic fields.

LPZ 2…n:

 Zone where the surge current may be further reduced by current distribution and isolation of interfaces and/or by installing additional SPDs on the sub distribution boards at the boundary. Additional spatial shielding will further reduce the electromagnetic field due to lightning.

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