Lightning

large lighting strikeThis June is potentially going to break records for rainfall but on top of that, we seem to be seeing more than the usual number of thunderstorms.

As lightning is an incredibly powerful burst of electricity, we thought it might be interesting to share some facts about lightning.

What Is Lightning?

Lightning is a very quick (each strike only lasts around 1 or 2 microseconds) but very powerful natural electrical discharge that happens during a storm. It can happen between clouds or between a cloud and the ground. It is a surprisingly common occurrence with around 100 cloud to ground lightning bolts striking the Earth’s surface every second. Each bolt of lightning can contain up to one billion volts of electricity and has an average temperature of approximately 20000 °C (36000 °F).

Lightning is more common over land than it is over oceans and around 70% of it happens in the Tropics. You will often hear thunder when you see lightning, this is because thunder is caused by lightning.

How Does It Happen?

During a storm, particles of rain, ice or snow collide which increases the imbalance between positive and negative charges. Negative charges (electrons) form at the bottom of clouds and positive charges (protons) form at the top of the clouds or sometimes objects on the ground such as trees, steeples or the Earth itself. The negative charge seeks out a positive charge to connect with and a current is passed between the two.

The intense heat of the lightning can heat the air around it to temperatures five times hotter than the surface of the sun. The heat causes the air to quickly expand and vibrate. This generates the thunder sound that usually accompanies lightning.

How Safe Is Your House?

Cloud to ground lightning will always try to find the easiest path to the ground. If there are conductive objects to follow they will provide potential routes but lightning can also reach the ground without any conductive objects. Houses contain lots of these routes such as pipes, phone lines, electric lines, gutters etc. Lightning won’t necessarily just take one path, sometimes it will branch and take more than one path at a time. It can also jump through the air between different conductive materials. This is known as a side flash.

The main types of hazard to a house that suffers a direct hit by lightning are:

  • Fire – houses contain lots of flammable materials such as wood or other building materials which can ignite if lightning passes through it. If lightning travels through a wire, it can burn up, causing a risk of ignition.
  • Power surge – if lightning selects a path via electrical wiring, the surge can damage anything that is connected. Electronics are most likely to suffer damage but even non-electronic appliances can be affected.
  • Shock wave – the explosive shock waves that lightning creates is what generates thunder. At close range, these waves can cause physical damage to concrete, brick, chimneys etc. They can even shatter glass or damage foundations.

The best way to stay safe during a storm is to stay away from any potential paths that the lightning may choose on its journey to the ground. Avoid things such as water from taps, showers or baths or using any wired appliance or tools. Stay away from metal framed windows. If your house does get hit, the first thing to check for is fire. If your home suffers a direct hit then it is a good idea to call the fire brigade in case a fire has started somewhere that isn’t immediately obvious. If you go outside, be wary of any falling debris.

In this country, we don’t necessarily have enough major lightning storms to justify the expense of a professionally installed lightning protection system but there are some precautions you can take. It is a good idea to unplug any expensive items during a storm and always check that your insurance covers lightning damage. In the worst case scenario, electronics can be replaced but consider the things that can’t such as computer data, work files, photos etc. Make sure that you have an adequate backup procedure and the backup device/facility is either off site or can be unplugged.

If you have any concerns about the electrical safety of your home, please contact us and we will be happy to help.