Conventional System Designed in accordance with NFPA780 and BNBC
What is Lightning Protection System?
Lightning is a gigantic electrical spark!
It has been measured Lightning discharges contain from several thousand amps to over 300,000 amps – enough to light half a million 100 watt bulbs!
The function of an external lightning protection system is to intercept, conduct and disperse a lightning strike safely to earth. Without such a system a building’s structure, electronic systems and the people working around or within it are all at risk.
Conversional LPS
Key Features
Major Components LPS designed in accordance with NFPA780 and BNBC
It has to be the highest point within its range
Air Terminal: The air terminal requires a connection to earth to perform its protective function. Copper and its alloys are the most common materials used in lightning protection.
Down Conductor must be installed straight and vertically to provide the shortest to earth
Down Conductor: The Down-Conductor is that part of the external Lightning Protection System (LPS) that conducts lightning current from the Air Terminal system to the Earth Termination system.
It is recommended that earth resistance value should be near 10 Ω
Earthing System: The earth rod requires a connection to earth to perform its protective function. This protects structures from damage due to lightning strikes and dilapidates the lightning to the ground
Lightning Protection System (LPS)
Comparison between two major methods of LPS
Early Streamer Emission (ESE) LPS
- Products for different coverage area are available
- Simple and cost effective
- Single air-terminal can cover over 300 ft. radius
- Generally Class II materials are used
- Regardless building height or size two grounding facility required
- Recommended for power station, golf field, commercial and residential projects etc.
- Latest technology
Conventional (Franklin Rod Method) LPS
- Custom Designed for individual building
- Require complex engineering to function properly
- Single air-terminal can cover up to 50 ft. radius
- Two classes of conductors used: Class I and Class II
- Depending on building perimeter, two or more grounding facility required
- Highly recommended for industrial sheds and buildings
- Traditional and proven technology
FAQs
-
Lightning is a giant spark of electricity in the atmosphere between clouds, the air, or the ground. In the early stages of development, air acts as an insulator between the positive and negative charges in the cloud and between the cloud and the ground.
The amounts of electrical energy traveling between cloud to cloud or cloud to earth, containing an average charge of 3,000,000 to 5,000,000 volts, a current of 300,000 amperes and a speed of 22 km/s. Even though a lightning discharge is of a very short duration (typically 200 microseconds) it is a very real cause of damage and destruction.
-
The function of an external lightning protection system is to intercept,
conduct and disperse a lightning strike safely to earth. Without such a
system a building’s structure, electronic systems and the people
working around or within it are all at risk. -
There is no direct answer to this question. However, there are different standards e.g. NFPA78o (USA), BNBC (Bangladesh), IEC, IEEE etc. which dictates different classes of construction and usage of LPS according to type, use, location, importance, make etc. Only an expert can determine if a construction will require LPS or not.
-
Bangladesh National Building Code (BNBC) first proposed in 1993,
made it mandatory in 2006 and a legal binding in 2015; gives clear
regulations for setting up “Lightning Arrestor” recommended for
buildings over 22m high and mandatory for buildings more than 33m
high. -
Fire Service and Civil Defense department and, Public Works Dept.
(PWD) of Bangladesh government are working relentlessly in lightning
awareness and protection in common people. It is obligatory to take
the NOC (No Objection Certificate) for all realtors which comply with
BNBC code.
Genesis Bangladesh
Engineering for Safer Tomorrow
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