Lightning Safety

The article below is replicated from the source indicated at the end. This is purely for information and knowledge:

What is lightning?
Lightning is a big charge of electricity that can reach from clouds to the ground or to other clouds. It can start fires and it is strong enough to hurt or kill people.
Is lightning really dangerous?
There are thousands of lightning strikes every day. Scientists think that lightning hits somewhere on the earth about 100 times every second. More people are killed by lightning than by any other kind of storm, including hurricanes and tornadoes.
Where can lightning strike?
Lightning can strike almost anywhere. Many people are struck before and after rain falls. Lightning can strike as far as 10 to 15 miles away from a storm. So, the blue sky above you is not a guarantee against a lightning strike from a storm looming in the vicinity.
There is also something called “dry lightning.” That is when lightning strikes from a non-rain bearing cloud. Dry lightning often causes forest fires because there is no rain to stop a fire from spreading.
How can you estimate the distance to a storm?
You can tell how far away lightning struck by counting seconds between the flash and the thunder. Every 5 seconds equals one mile, so if you count 10 seconds until you hear the thunder, the lightning flash was 2 miles away. A six miles estimate (a 30 second count) would make you in the high danger zone.
Lightning Safety Position
Lightning safety experts have suggested a “lightning safety position” that is very important to know if you are caught in a thunder storm and you can’t find a shelter.

“Keep both feet on ground and crouch with the heels together. Cover your ears with your palms to minimise hearing damages due to thunder”.

This position looks hard to achieve, but it could save your life. The reasons for doing it are as follows:

  • It makes you a smaller target.
  • With your heels together, if lightning hits the ground, it goes through the closest foot, up to your heel and then transfers to the other foot and goes back to the ground again. If you don’t put your feet together, lightning could go through your heart and kill you.
  • The hands over your ears protect them from thunder shock waves.

First Aid
Persons struck by lightning receive a severe electrical shock and may be burned, but they carry no electrical charge and can be handled safely.
If a victim is not breathing, you should immediately begin mouth-to-mouth resuscitation, once every 5 seconds to adults and once every 3 seconds to infants and small children, until medical help arrives.
If both pulse and breathing are absent, cardiopulmonary resuscitation–a combination of mouth-to-mouth resuscitation and external cardiac compression–is necessary. This procedure should be administered only by persons with proper training.
Victims who appear only stunned or otherwise unhurt may also need attention. Check for burns, especially at fingers and toes and next to buckles and jewelry. Give first aid for shock. Do not let the victim walk around. Send someone for help. Stay with the victim until help arrives.
Personal Lightning Safety Tips

  1. Wherever you are, when you first see a lightning or hear thunder, activate your emergency plan. Lightning often precedes rain, so don’t wait for the rain to begin before suspending your current activities.
  2.  If outdoors……Avoid water. Avoid the high ground. Avoid open spaces. Avoid all metal objects including electric wires, fences, machinery, motors, power tools, etc. Unsafe places include underneath canopies, small shelters, or near trees. Where possible, find shelter in a substantial building or in a fully enclosed metal vehicle such as a car, truck or a van with the windows completely shut.
  3.  If lightning is striking nearby when you are outside, you should crouch down. Put feet together. Place hands over ears to minimize hearing damage from thunder. Avoid proximity (minimum of 15 ft.) to other people.
  4. If indoors… Avoid water. Stay away from doors and windows. Do not use the telephone. Take off head sets. Turn off, unplug, and stay     away from appliances,computers, power tools, & TV sets. Lightning may strike exterior electric and phone lines, inducing shocks to the indoor equipment.
  5. Suspend activities for 30 minutes after the last observed lightning or thunder.
  6. Injured persons do not carry any electrical charge and can be handled safely.  Apply First Aid procedures to a lightning victim if you are qualified to do so. Call the applicable medical emergency number for assistance or send for help immediately.

Lightning Protection Codes and Standards
Some of the country codes are;

  • Singapore’s CP 33
  • Australia/New Zealand’s AS/ANZ- 1786
  • South Africa’s SABS-03
  • Indian IS-2309
  • UK – BS-665,
  • German VDE-0185
  • Chinese GB 50057
  • Russian RD 34.21.122-87
  • Polish PN-86/E-05003/01.

So far, no universal lightning risk management code exists. The closest candidate is the International Electro-technical Commission IEC 61024, which is said to be the “single best reference document for the lightning protection engineer.”
Lightning Risks Assessment
Damage to property—especially for aircraft, large industrial or commercial facilities, and the petroleum, explosives manufacturing and defense industries—is a grave threat.
The amount of damage lightning does to these targets is growing because more lightning-sensitive equipment (anything containing low-voltage microprocessors) is being used.

The Hazard Analysis

The hazard analysis is an engineered safety process to control, eliminate, identify or isolate perils, threats, and uncertainties. The process should commence at once and be an ongoing endeavour. Well-known techniques for this include: analysis of conceptual and pre-construction drawings; engineering and operational changes analysis; mishap investigation; readiness reviews; walk downs and surveys; and publishing safety
information such as material safety data sheets and “lessons learned” summaries. To assist in identifying operational hazards, the associated threats from lightning are described in summary form:

  • Direct Strike. This is the most dangerous hazard, wherein the person or structure is a direct path for lightning currents to seek ground. The magnitude of the current determines its effects. Typical amperage of 20kA acting on a ground of 10 ohms creates 200,000V. A large strike can attain 150kA levels.
  • Side Strike. This hazard results from the breakup of the direct strike when alternate parallel paths of current flow into the ground via a person or structure. When the initial current path offers some resistance to current flow, a potential above ground develops and the person or structure’s resistance to ground becomes the alternate path of conduction.
  • Conducted Strike. This hazard occurs when lightning strikes a conductor which in turn introduces the current into an area some distance from the ground strike point. Unprotected connected equipment can be damaged and personnel injured if they become an indirect path in the completion of the ground circuit.
  • Structure Voltage Gradient. When current passes through two or more structures, it creates momentary voltage differentials. Poor interconnect bonding may cause a completed circuit potential difference. The same hazard is created, for example, by a person touching an ungrounded object while he himself is grounded – the electrical circuit is completed through him, sometimes with fatal consequences.
  • Induced Effects. Lightning can induce electric field and magnetic field coupling into structures and into wiring. Magnetic coupling is transformer action, and the common laws for transformers prevail.
  • Step Voltage/Touch Voltage. This hazard occurs as a result of a lightning strike hitting the ground and dissipating its energy through the ground. The ground current creates a voltage drop across the surface of the earth, emanating from the earth entry point radially. A person standing on the earth within several hundreds of feet from the lightning strike point can have several hundreds of volts generated between his feet. This hazard is identical to a person being grounded while touch two live wires, one with each hand.

Source: National Lightning Safety Institute, USA

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