Difference Between Lightning Protection & Surge Protection Devices
Lightning protection is to be installed at the primary level for the protection of structures or
buildings for protection of tall structures or buildings from direct lightning strikes. This is a first
line rescue system that can be a conventional franklin rod network on the top of the roof with
down conductor connecting to the earth termination system as per NBC 2016 & IS/IEC 62305.
Whereas, when it comes to ​Surge protection devices​, they generally are devices installed at the
equipment level/ secondary equipment. They are for transients of the waveform of both
10/350µs (lightning surges) and 8/20µs (switching surges) which are called direct lightning &
switching surges.
Need for External Lightning Protection System & Surge Protection Devices
In general, as per latest codes & standards, the complete lightning protection system is divided
into two parts- i) External Lightning Protection System; ii) Internal Lightning Protection System.
Looking for the protection of your building or structures? Then you certainly have to go for the
external lightning protection system as it protects your structure from outside. It detours the
lightning discharges away from objects in its protection zone and redirects it safely to the
ground.
The parts and parcels of the system is a network of air terminals installed on the highest point;
corners & edges of the roof connected with parallel conductors providing multiple paths for the
struck lightning. They are then connected to the down conductors isolated from the walls,
which then conveys this excess energy safely to the ​earthing system​.
But this does not serve the complete purpose as it does not protect the sensitive electronic
equipment inside your facility. There comes the requirement of special devices called transients
suppression units or surge protection devices which shall be installed at the main LT panel &
Sub distribution board that monitors the internal voltage of the associated devices and comes
into action as and when a transient voltage is detected.
Surges simply means an increase in the normal prescribed voltage level of a particular
associated device or an electric network. They are very swift and stay in any network for a few
nanoseconds making it difficult to detect by normal fuses or circuit breakers. Hence, it is
important to have a surge protection system complying to IEC 61643 & IS/IEC 62305-4 along
with the ​lightning protection system as per IS/IEC 62305 – 1 to 3 and NBC 2016 to avoid
electric hazards and fire hazards.
At present, the outdoor and indoor environment is precarious and extensively unforeseeable
because of which the installation of additional lightning and switching surge protectors are
mandated and highly recommended as per mandatory codes and standards.