Lightning, Ben found out the hard way

You’d be shocked how much damage lightning can cause

By John D’Annunzio, Columnist,

This article is about lightning strikes to buildings and lightning rod systems. To understand the way a lightning rod works, however, we should first take a look at how lightning develops.

It all starts when a cold and warm air mass clash together causing a thunderstorm. There is positive and negative energy preceding a storm which causes negative energy to rush to the ground. This result of this rapid descent is the sound of thunder and the visual flash of lightning from the earth to the sky.

About 5.5% of homeowner’s insurance claims are lightning related and the damage caused by lightning is estimated to be over $1,900,000,000 per year.

A bolt of electricity can produce a minimum of 20 million volts, and most are significantly greater than that. There can be 30 or more lightning strikes in any square mile in the United States per year.

Here is an idea how a lightning rod system works:

First it will not attract or repel a lightning strike. When lightning leaves the clouds, headed downward towards the ground, an equal and opposite ground charge is seeking a path upward to meet or neutralize the cloud charge.

Now, when a cloud charge is over a house with a lightning rod system, the earth charge uses this system and dissipates out of the top of the air terminals (lighting rods) and the two charges meet at a location called striking distance, usually 150 feet, more or less, above the ground. A typical system is made up of the following components:

1) Air terminals –or “lightning rods are installed on ridges, chimneys, or any high point.

2) Conductors- are copper or aluminum and are braded; these conduct the electricity to a ground rod.

3) Ground rods – are copper clad steel rods installed about 10 feet in the earth.

4) Surge suppression device (optional)- which includes surge arrestors installed where utilities such as electrical service, telephone, and cable or satellite enter a building .

When a nearby utility pole or transfer station gets struck by lightning, damaging surges can come down the wires into your building. Surge arrestors, however, can stop these surges before they start electrical fires and cause damage to computers, electronics, and appliances.

Lightning rod systems must comply with NFPA (National Fire Protection Agency) 780 and UL (Underwriters Laboratory) 96A and make sure the installer is following local township guidelines.

Do you get a discount on homeowner’s insurance? Policies vary by insurance company, but many offer a discount for lightning suppression systems.

As far a cost, it can vary widely depending on building size and complexity. Just multiply the square footage of a structure times $2 to $3 a Sq. Foot.

Don’t be like Ben, save yourself the shock of lightning damage and look into a lightning rod.

John D’Annunzio is a local Commercial and Residential builder who has held nearly every job in the construction industry from heavy equipment operator to home builder. He is ICC building code certified and lives and operates in Chester County, PA. His column will appear weekly and address various home improvement and building issues with special attention to subjects of interest locally.

Contact John at

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