More About Lightning and Surges

Lightning is a massively powerful, random and unpredictable event. Its’ physical characteristics include current levels sometimes in excess of 400 kA, temperatures to 50,000 degrees F., and speeds approaching one third the speed of light. Globally, some 2000 on-going thunderstorms cause about 100 lightning strikes to earth each second. Insurance company information shows one homeowner’s damage claim for every 57 lightning strikes. Annually in the US lightning causes more than 26,000 fires with damage to property in excess of $5-6 billion!

Lightning strikes to earth, as presently understood, follow an approximate behavior:

1. Leaders from a thundercloud pulse towards earth seeking out active electrical ground targets.

2. Ground-based objects (fences, trees, blades of grass, corners of buildings, people, lightning rods, etc., etc.) emit varying degrees of electric activity during this event. Upward Streamers are launched from some of these objects. A few tens of meters off the ground, a “collection zone” is established according to the intensified local electrical field.

3. Some Leader(s) likely will connect with some Streamer(s). Then, the “switch” is closed and the current flows. We see lightning.

Lightning often strikes power lines, towers,  transformers and sub-stations. These strikes may travel along power lines for miles, affecting homes and businesses with disastrous results. Lightning effects can be direct and/or indirect. Direct effects are from resistive (ohmic) heating, arcing and burning. Indirect effects are more probable. They include capacitive, inductive and magnetic behavior. Lightning “prevention” or “protection” (in an absolute sense) is impossible. A diminution of its consequences, together with incremental safety improvements, can be obtained by the use of a holistic or systematic hazard mitigation approach. Often, a whole-house surge protector can stop this current in its tracks before it has the chance to damage your furnace, televisions, and other electronics. In cases where the property is severely exposed to lighting strike risk, lightning rod systems may be installed to provide a direct lightning barrier.

See your experienced electrical surge team at Solutions Electric to find out how to reduce your exposure to severe damage in your home.

References

1. API 2003, Protection Against Ignitions Arising out of Static, Lightning, and Stray Currents, American Petroleum Institute, Washington DC, December 1991.
2. Golde, G.H., Lightning, Academic Press, NY, 1977.
3. Hasse, P., Overvoltage Protection of Low Voltage Systems, Peter Peregrinus Press, London, 1992.
4. Hovath, Tibor, Computation of Lightning Protection, John Wiley, NY, 1991.
5. IEEE Std 1100, Powering and Grounding of Sensitive Electronic Equipment, IEEE, NY, NY. 1992.
6. KSC-STD-E-0012B, Standard for Bonding and Grounding, Engineering Development Directorate, John F. Kennedy Space Center, NASA, 1991.
7. Morris, M.E., et.al., Rocket-Triggered Lightning Studies for the Protection of Critical Assets, IEEE Transactions on Industry Applications, Vol. 30, No. 3, May/June 1994.
8. Sunde, E.D. Earth Conduction Effects in Transmission Systems, D. Van Nostrand Co., NY, 1949.
9. Towne, D., Wave Phenomena, Dover Publications, NY.
10. Uman, Martin, Lightning, Dover Publications, NY, 1984.
11. Viemeister, Peter, The Lightning Book, MIT Press, Cambridge MA, 1972.