Lightning 101 - Introduction to Lightning

Lightning is a very dangerous weather phenomenon that causes over a billion dollars of damage a year world-wide. So it is obvious that understanding lightning is important in explaining the effects of lightning on equipment and also how many of LEC’s products work.


Multiple lightning strikes together
Global lightning facts:

  • 45,000 lightning Storms every day
  • 2,000 lightning storms every moment
  • 100 cloud-to-ground strikes per second
  • $1 billion annual global damage

How Lightning Strikes Form

As a thunderstorm grows, charges build up in the cloud. The bottom usually develops a large negative charge while high at the top of the cloud a positive charge develops. Ninety percent of all lightning flashes occur within the cloud. When a thunder cloud moves over an area, it can induce an intense charge of opposite polarity on the ground below. This is called the cloud electrical shadow, and results in unequal and constantly changing ground potential. Everything within the electrical shadow accumulates and dissipates this charge at varying degrees:

  1. Conductors (metal structures, storage tanks, wiring/piping, and grounding grids) - collect and dissipate these charges most quickly (microseconds).
  2. Products within containers (petroleum, military ammunition) - collect and dissipate these charges relatively slowly (the rate is highly dependent on surrounding insulators vs. conductors)
  3. Insulators, and some insulated products - collect and dissipate these charges most slowly.
  4. The ground (earth)- collects and dissipates these charges on a grand scale but the rate is very dependent on geological factors (soil resistivity, moisture, stratifications, lakes and rivers, etc.)

If all of the above components are interconnected (using an effective common grounding mechanism), their charges will rise and fall together, keeping the charge across the system in balance. If the components are not interconnected, then the charges grow and shrink independently causing ground potential differentials, and the creation of “Bound Charges”. If the intensity of a Bound Charge becomes big enough, it will try to dissipate following a path of least resistance which can either be to follow grounding structures or wiring or to arc to a nearby conductor which has less resistance and/or impedance. As the storm intensifies, so do the magnitudes of these charges, and when the air between the cloud and the earth can no longer act as an insulator a cloud-to-ground spark (or lightning strike) occurs. Lightning always “chooses” to follow a path of least resistance/impedance.

Thunder storms and lightning strikes have the following characteristics:

  • Total Cloud Charge: 10 to 40 Coulombs
  • Average Cloud Charge: 30 to 90 Coulombs are discharged
  • Charge Transfer per Flash: 25 Coulombs Discharged
  • Average Transfer per Flash: (EFS) 5 to 30 to 300 kV/m
  • Electric Field Strength: Dependent on humidity, temperature & pressure
  • Average EFS for lightning: 10 kV/m (required to breakdown the insulation threshold of moist air)
  • Multiple Upward Streamers: 100 to 300 kV/m (usually under drier conditions)
  • Peak Voltage: One to Ten Billion Volts, 50% at 100 Million Volts
  • Peak Current: 2 to 510 kA (usually the return stroke) 99% < 200 kA 50% @ 30 kA
  • Polarity Negative: > 90%
  • Duration (99%): 30 to 200 ms (average duration of single return stroke 50ms)
  • Number of Strokes per Flash: 1 to 26 50% > 4 10% > 9
  • Lightning RFI Range: 1 kHz to 100 MHz 95% 200 kHz to 20 MHz
  • Temperature: 50,000 F Pressure 10 atm (causing sonic boom = thunder) Many bad things happen when lightning strikes, resulting in various direct and secondary effects.

Direct Effects of Lightning

A Direct strike can have the following effects:

  1. Heat: fires, structural damage from instant vaporization of trapped moisture (example: explosions of concrete or trees)
  2. High voltage and high current surges along conductors over long distances (along lightning rods to grounding rods, and along any electrically or metallically connected equipment)
  3. High voltage and high current surges along the ground over shorter distances.
  4. If a strike hits an individual it can cause severe injuries or even death.

Secondary Effects of Lightning

When lightning strikes nearby within microseconds the strike lowers (or neutralizes) the local ground charge and all interconnected conductors. However, The accumulated charge of some objects such as the fluid of a storage tank, does not discharge as quickly, resulting in a temporary “Bound Charge”. People, computers and electronic equipment, transformers and certain electrical equipment, and flammables do not like being hit by lightning, or being anywhere near where it strikes.

Lightning Protection Solutions

All of LEC’s Products have been precision engineered to provide the best and most reliable protection against all the hazards of lightning (surge, grounding, lightning protection) and bound charge (grounding), review our solutions to learn more or contact us and a representative will help find the best engineered solution for you.

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