Lightning can strike anywhere and anytime, make sure you are protected. Although most of our work has been in Northern Lower Michigan and the Upper Peninsula of Michigan we have the capability to provide lightning protection throughout the United States. Call us at at 231-228-4112 and let’s discuss how we can protect your home or building from a lightning strike.
Lightning Protection is a system that is designed to send the path of lightning directly to the ground rather than it dispersing throughout your home or business causing damage and injuries.
A lightning protection system does not increase or decrease the chances of your building being struck by lightning; it decreases the chances of damage or injury if you are struck.
The cost of a lightning protection system varies based on size and design. There is a substantial savings if the system is installed during the construction phase. We will provide a free estimate.
Lightning can strike the same place twice, if your surroundings are attractive to lightning you may see lightning strike twice.
A metal building is usually less than 3/16” thick. NFPA 780 states that metal bodies 3/16″ thick or thicker will take a direct lightning strike and conduct it to a grounding system such as structural steel framing members (heavy steel columns and beams). Thin metal will melt through where the lightning attaches, so to protect the moisture seal of the roof, you need strike termination devices or lightning rods. The roofing isn’t a valid conductor, so you need cable conductors to the grounding system. A metal building or roof area is protected the same way you protect a non-metallic building, either wood or concrete.
Houses are grounded from the standpoint that they have an electrical system ground, communication system ground, maybe a data system ground, and metallic piping systems (water, sewer, gas) that enter the ground. This is a good and a bad thing. Lightning wants to get to ground by the easiest method available. If allowed to advance with no control mechanism through a structure, it may move from grounded system to grounded system “jumping” or side-flashing through the house. When these various grounded systems are not intentionally interconnected or bonded together near grade (which sadly is typical of most houses) then the jumping can occur from a less suitable ground path (a poorly grounded water line) to a better path (the electric service ground). When lightning jumps through free air, it can be dazzling as in “ball” lightning. When it jumps through building materials it may cause fires or even explosion from superheating. Plastic piping is not a conductor, but a system with partially plastic and metallic sections can lead to this side-flashing phenomena.
In some areas of the country it is very common for houses to have lightning protection systems. If you look at Annex L of NFPA 780, there is a risk assessment calculator for structures. Certainly the fact that residences are smaller buildings may be in areas of lower lightning activity, or do not have the occupancy of other structures can have an impact on risk or consequences. It seems that a more pertinent factor may be whether there is anyone in a local area promoting and selling lightning protection, thus raising awareness of the fact that lightning protection is effective and affordable. In the early part of the last century, insurance companies allowed credits for lightning protection systems for some residential structures particularly those remote from fire protection. Today, most insurers just lump lightning losses with all fire losses, rather than giving a separate credit. This is an area that we continue to work on to make protection more affordable. It may seem more likely that lightning will strike larger buildings, but it is a fairly random occurrence in any area so it depends on how much exposure you can stand. I have lightning protection on my house. I’m building a new house with lightning protection on it. In fact, I don’t remember ever living in a house without lightning protection on it.
The answer to your question depends on how you look at things, and that’s where a lot of confusion lies. Clouds become charged through the separation of ions created by dust particles and ice crystals “rubbing” together as winds and up-drafts circulate around. These ions generally accumulate in different portions of the cloud, and once they reach a level of intensity that allows for the breakdown of a very good insulator (air) they begin to reach down from the cloud, approaching earth or anything ground mounted. These invisible “feelers” reaching toward earth are called step leaders (they can be viewed and studied with an infrared lens). When they reach a certain point above earth or a ground-mounted object dependent on the intensity of the step leader, they pull ions of opposite charge up from ground-mounted objects, called streamers. Pointed objects or edges release ions more easily, so a flagpole, roof ridge, building corner, or the branches of a tree can provide an improved attachment point. Once the ions pulled up meet the step leader from the cloud, you have a complete circuit and the visible lightning bolt, or interchange of ions to neutralize the electrical imbalance. Several return strokes may follow the same path causing the “flickering effect”. Ions located in the base of the cloud are generally negatively charged, so most lightning strikes (around 92%) are negative cloud to positive up from the ground. Positively charged sections of the cloud, normally near the top (“cloud anvil”), can also pull negative ions from below, generally from tall radio or TV towers, and account for the balance of strikes.
Indirect lightning may be the name used for a variety of situations. A direct strike is fairly straight forward, but associated consequences may not be. There can be side flashing within a structure between separately grounded systems if they are not interconnected. The massive electromagnetic force of a lightning strike may cause inductance to wiring for any system in close proximity to the path of the lightning between a roof and the ground. Once lightning reaches the ground, it spreads over the surface of the earth for a distance to neutralize the charge with the distance dependent upon the electrolytic content of that particular soil structure. This causes an “electrified grid” effect, which may impact anything in the vicinity – people standing on the ground, earthing or grounding devices buried in the ground, or metallic piping systems. Lightning may strike utility lines and be carried into the structure if surge suppression is not applied at service entrances. This is why bonding of all building systems at grade, interconnecting long grounded systems near their top within a structure, and surge suppression is so important – all parts of a complete lightning protection system along with the direct strike protection.
The Lightning Protection Institute- www.Lightning.org