© UPLS 2022
Lightning is one of nature's most powerful and destructive phenomena
Lightning discharges contain awesome amounts of electrical energy and have been measured from several thousand amps to over 200,000 amps - enough to light half a million 100 watt bulbs! Even though a lightning discharge is of a very short duration (typically 200 microseconds) it is a very real cause of damage and destruction.
The effects of a direct strike are obvious and immediately apparent - buildings damaged, trees blown apart, personal injuries and even death. However, the secondary effects of lightning - the short duration, high voltage spikes called transient overvoltages can and do, cause equally catastrophic, if less visually obvious, damage to the electronic systems inside a building.
Protecting electronic systems
We are continually meeting people who have structural lightning protection for their building, but have suffered damage to the - unprotected - electronic systems within. Simply stated, a structural lightning protection system cannot and will not protect the electric systems within a building from transient overvoltage damage.
A total solution
A reliable lightning protection scheme must encompass both structural lightning protection and transient overvoltage (electric systems) protection. That's why we advocate a Total Solution approach to lightning protection - to ensure complete protection of your employees, the fabric of your building and the electronic systems therein.
Why is lightning protection so important?
The function of an external lightning protection system is to intercept, conduct and disperse a lightning strike safely to earth. Without such a system a building's structure, electronic systems and the people working around or within it are all at risk.
There are many ways in which lightning strikes can cause damage or injury. Lightning strikes (or even electrical discharges due to nearby lightning) can cause fires, explosions, chemical release or mechanical disruption within or around a building. Step and touch voltages generated from a lightning strike can cause injury, or even loss of life, to humans (and animals) in the close vicinity.
Benjamin Franklin came up with early lightning protection.
Though his "kite experiment" about the nature of electricity may or may not have actually happened, Franklin did come upon the idea of securing lightning rods to the tops of buildings in order to protect structures from the impact of lightning strikes. The Franklin lightning rod, he said, would prevent a house from being "damaged by lightning … passing thro the metal into the ground without hurting anything."
Once Franklin had an understanding of the behavior of electricity, he set about to protect houses from the destructive forces of lightning. A lightning rod, simply, is a rod attached to the top of a building, connected to the ground through a wire. The electric charge from lightning strikes the rod and the charge is conducted harmlessly into the ground. This protects houses from burning down and people from electrocution.
In a 1753 edition of Poor Richard's Almanack, Franklin published this description of his invention:
It has pleased God in his goodness to mankind, at length to discover to them the means of securing their habitations and other buildings from mischief by thunder and lightning. The method is this: Provide a small iron rod (it may be made of the rod-iron used by the nailers) but of such a length, that one end being three or four feet in the moist ground, the other maybe six or eight feet above the highest part of the building. To the upper end of the rod fasten about a foot of brass wire, the size of a common knitting needle, sharpened to a fine point; the rod may be secured to the house by a few small staples. If the house or barn belong, there may be a rod and point at each end, and a middling wire along the ridge from one to the other. A house thus furnished will not be damaged by lightning, it being attracted by the points, and passing through the metal into the ground without hurting anything. Vessels also, having a sharp point rod fixed on the top of their masts, with a wire from the foot of the rod reaching down, round one of the shrouds, to the water, will not be hurt by lightning.
To understand the need for surge protection, it is important to understand how lightning causes damage.
The sources of lightning damage are quite different, and we use different types of mitigation techniques and equipment to protect different items.
There are two areas of concern when evaluating a building or structure, namely the structure itself, and all incoming cables, meaning IT equipment as well as power. The four sources of damage are derived from these, and manifest as:
Lightning strike directly to the building.
Lightning strikes near the building.
Lightning strike directly to an incoming line.
Lightning strike near to the incoming line.
Nearby strikes cause lightning surges. When striking neighbouring buildings, surrounding objects or areas adjacent to incoming lines, the lightning current generates a magnetic field that is cast over the structure or lines. This magnetic field generates induced current on the incoming line or on the cables inside the structure. To prevent damage to electrical equipment, we use surge protective devices (SPD) to reduce the induced effects of lightning. To prevent burning or mechanical damage, we avoid direct strikes to structures by means of a system of lightning rods, also known as external lightning protection.
By installing external protection, you will protect yourself from structural damage, but this will not necessarily prevent your electronic equipment from being damaged (TVs, internet routers and appliances such as kettles, fridges, microwaves and others). Therefore, in order to protect equipment, you need surge protective devices.
The calculation from the SANS 62305-2 standard to evaluate the risks is as follows:
The area to be considered for direct strikes is a radius around the structure, which is three times the height of the structure
The area to be considered for surges is a radius of 500 m around the structure and can be up to 2 km away in both directions for incoming lines.
We can therefore see that the risk of resultant surges exceeds that of direct lightning strikes, meaning that the correct installation of surge protection devices is extremely important.
Other benefits of surge arresters include the minimising of switching surges coming from the grid. This is a very relevant topic when seen against the background of recent load shedding from the South African grid.
Lightning is known to be the most significant source of surges—bolts have been recorded to have a million to a billion volts and between 10,000 to 200,000 amps. However, lightning only makes up a portion of all transient events in a facility.
Because transients can originate from both external sources (like lightning) and internal sources, facilities ought to have both a lightning protection system and surge protection installed.
This begs the question: what is the difference between these two systems, and how do they work together?
Lightning Protection System
Quite simply, a lightning protection system protects a structure from a direct lightning strike.
To do this, an air terminal (or system of air terminals) is placed in the most probable position to capture the direct strike, based on the structure’s architectural design and roof equipment. The rest of the system is designed to safely convey that electrical energy from the lighting strike to ground as efficiently and safely as possible.
To intercept the strike and conduct the high current energy of a lightning strike into the earth, system components include the:
Air terminal, which is used to intercept the lightning strike.
Down conductors, providing the most direct path possible to move the electrical energy towards the ground.
Grounding system, which provides a path for the current to dissipate into the ground and out of harm’s way.
Bonding, meant to reduce the possibility of voltage differences that are a safety risk.
Lightning protection standards ensure how to properly place air terminals, run cable, ground and bond in order to ensure maximum safety in this energy transfer and dissipation.
Surge Protective Device (SPD)
A surge protective device (SPD) is designed to protect electrical systems and equipment from surge and transient events by limiting transient voltages and diverting surge currents.
What causes transients and surges?
Lightning is the most spectacular form of an externally generated surge, however, it is estimated that 65% of all transients are generated internally within the facility by the switching of electrical loads such as:
How does a SPD work?
There is at least one non-linear component of the SPD, which under different conditions, transitions between a high and low impedance state. At normal operating voltages, the SPDs are in a high impedance state and do not affect the system. When a transient voltage occurs on the circuit, the SPD moves into a state of conduction (or low impedance) and diverts the transient energy and current back to its source or ground. This limits or clamps the voltage amplitude to a safer level. After the transient is diverted, the SPD automatically resets back to its high impedance state.
What Sets the Two Systems Apart?
On a basic level, the lightning protection system protects the facility and structure from direct strikes, while SPDs protect electrical equipment and systems against surges or transients.
How the two operate, and the components involved, also vary. Lightning protection system components are always in place and ready to function, while SPDs monitor internal system voltages and spring into action if a transient voltage occurs on the circuit.
How the Two Work Together
Though lightning is not the most common transient event, it is the most significant. While a lightning protection system protects the exterior against the affects of lightning, SPDs must be in place to support the other system and the related transients a strike creates. SPDs will activate and begin to conduct energy into the grounding system if surges to bonded equipment exceed the designated rating.
Lightning is the most likely external cause of a significant surge, and SPDs must be installed to limit currents entering into the internal environment, showing the importance of an interconnected facility electrical protection system.
Lightning protection standards—such as National Fire Protection Association (NFPA) 780, UL 96A, LPI 175, IEC and BS standards in the handbook—outline the special considerations for SPDs for use with lightning protection systems.
Essentially, a surge protector device must be rated for use with the lightning protection system according to its Nominal Discharge Current, or the peak value of In (8/20 μs) that the SPD can still function at after 15 applied surges. According to UL 96A, for example, service entrance SPDs must have a Nominal Discharge Current rating of 20 kA.
Not all UL listed SPDs are necessarily rated for use with a lightning protection system. What this rating means is that it can handle greater surges than devices with a lower In rating.
Class 1 – (10/350) LIGHTNING CURRENT ARRESTERS which can withstand direct lightning
Typical surge handling ability must be 12.5kA (10/350) per phase.
Whenever a building has external lightning protection such as a mast, or conductors on the building, Class 1 lightning current arresters are required.
These units are designed to withstand direct lightning surge currents and are very robust devices, but on their own cannot clamp the voltage to low enough levels to protect sensitive electronics. Thus Class 1 lightning current arresters must always be used in conjunction with Class 2 surge arresters (8/20). Please note that when using a Class 2 surge arrester in conjunction with a Class 1 lightning current arrester you require a minimum of 10 –15 meters of cable between the units for de-coupling. There are special coils available that can be used to simulate 15m of cable.
If you did not use a Class 2 surge arrester in conjunction with the Class 1 lightning current arresters, surge up to 3kV could enter the system and the surge arresters would not operate thus damaging sensitive electronics.
Class 2 – (8/20) SURGE ARRESTERS, to protect against induced surge currents
In all cases, you must install a minimum of a Class 2 surge arrester in the main electrical distribution board.
The SANS 10142-1:2003 requires that these surge arresters must withstand a nominal surge current of 5kA and a peak surge current of 10kA. Experience has shown this to be inadequate.
The IEC requires a nominal surge current rating of 10kA and 25kA peak surge current.
All surge arresters must have a disconnection mechanism with a visual indication showing end of life, this can be a mechanical flag or a light. Whenever a building has external lightning protection such as a mast, or conductors on the building, Class 1 lightning current arresters are required.
Class 1 & 2 – (8/20) COMBINATION SURGE ARRESTERS, to protect against induced surge currents
To overcome the problem of coordination of Class 1 and Class 2 arresters a combined surge arrester has been developed which eliminates this problem.
A further advantage of this combination is that it halves the clamping voltage Phase to Neutral when compared to the standard method of installing surge arresters from each Phase and Neutral to Earth and it can be used on all types of wiring applications earthing systems. This means you can install it in a container such as an electrical distribution board and have complete protection.
These units can take a direct strike and limit the voltage to less than 1,5kV as required by SANS 10142-1:2003.
Class 3 – (8/20) SURGE ARRESTERS, to protect against induced surge currents
When using Class 3 surge arresters there must always be Class 2 surge arresters installed upstream to ensure that the units will not be overstressed.
These units are typically 5kA (8/20) devices and are used to dissipate any surges that may be induced between the electrical distribution board and the equipment.
Class 3 surge arresters without internal disconnecting mechanisms may only be used in circuits that are supervised by earth leakage devices.
Facts about lightning in South Africa
It is a fact that the highveld region of South Africa and Lesotho have amongst the highest lightning strikes per square km per annum in the world.
On average every square km of South African highveld and Natal receives 7 direct lightning strikes per annum.
The facts are a direct or indirect lightning strike within a 1,5km radius of your home or office can generate as much as 120 million volts and up to 180 000 Amps, sending lethal surges ripping through power cables and telephone lines. The core temperature of a lightning strike is as high as 20 000 deg C or five times as hot as the surface of the sun.
Statistics prove that as much as 80% of problems on electronic equipment are associated, directly or indirectly, with lightning and overvoltage surges.
An average of 1,000 people each year experience lightning-related injuries, including heart attacks, lung damage, eardrum ruptures, burns, and even broken bones. To protect your family members from the dangers of lightning, advise them to come indoors any time they hear thunder or see lightning flashes.
To protect your family while they are inside your home, ensure your home has a lightning protection system. A lightning protection system consists of a series of rods and conductor cables that direct the electronic charge that lightning carries away from your home and deep into the ground.
Contrary to popular belief, lightning protection systems do not attract lightning. Instead, they simply offer lightning a path to the ground with very little resistance; lightning is attracted to the ground due to the positive charge it carries and is always looking for a path to it.
When lightning is attracted to this system instead of the less conductive materials your home is composed of, you can feel better that your family is safe and secure from lightning-related injury or death when indoors.
Don't believe every myth you hear about lightning because it is a hazard that kills and injures many people each year. Contact Universal Lightning Protection Services to discuss your residential Lightning Protection System options.
Your business is exposed to serious risks if you haven't installed a lightning protection system on your premises. Here are a few specific examples of how a lightning strike can paralyze your business operations.
Start a Fire Outbreak
A lightning strike can cause a fire outbreak in two main ways. First, lightning itself heats up the air around it, and the heated air, which can be extremely hot, can easily ignite the surrounding environment. Your file cabinets, window treatments or even furniture can easily ignite and spread the fire to the rest of the office.
Secondly, lightning can cause a fire outbreak by causing electrical malfunctions (such as a short circuit) that can trigger an electrical fire and burn down your business.
Fry Up Your Electrical Wiring
All wiring has a maximum voltage amount it can safely handle. Several things can happen when lightning forces electrical wiring to carry a voltage beyond this limit.
For example, the electricity overload will heat up the conductors (due to the increased electrical resistance) and even damage their insulation. Not only that, but some of the electricity may be forced to flow through unintended paths (classical short circuit) causing further damage. All these damages mean that, in a worst-case scenario, you will have to replace your electrical wiring after a lightning strike.
Damage Your Electronics and Electrical Items
In the case of a powerful lightning strike, the damage may extend from the electrical wiring to the electronics and electrical items. Just like the electrical wiring, the electronics and electrical items in your business also have a maximum amount of electricity they can handle.
Unfortunately, if lightning strikes your electrical wiring, the electricity may pass through and overload the plugged-in electronics and electrical appliances, damaging them too. The damages mean you will have to replace the wiring and the electronics/electrical items.
Injure Your Employees
One of the worst things about a lightning strike is the injuries it can cause to those at the scene of the strike. A typical lightning bolt contains millions or even a billion volts of electricity, which is not safe for a human body.
Even if the strike doesn't hit your employees directly, it may pass through other items in the workplace and still reach the employees. In addition, consider the risk of getting trampled in a stampede after a lightning strike, getting injured by malfunctioning appliances, or getting burned by a lightning-induced fire.
All these risks mean that your employees may be severely injured if you don't have lightning protection for your workplace.
Trigger Liability Claims
A lightning strike can trigger liability claims or even a lawsuit against your business in two main ways. First, a lightning strike may cause injuries to your visitors (such as clients) who were on the premises at the time of the strike. The victims of the accident may sue you if they are convinced that you could have prevented their injuries if you had installed a lightning arrester.
Secondly, your business may also face liability claims or lawsuits if the lightning strike causes damage to your client's belongings or delays your service delivery to your clients.
Create an Uncomfortable Working Environment
Lastly, a lightning strike may also render your business premises unbearable if it knocks out your heating and cooling system or damages your plumbing system. For example, a lightning strike could damage your plumbing system and flood your premises with water. Damages to heating, cooling, and plumbing systems may force you to give your workers time off until you can fix the damages.
The good news is that you don't have to expose your business to the above risks. At Universal Lightning Protection Services, we understand the danger of lightning strikes and we can design and install a suitable lightning protection system for your business.
“When thunder roars, go indoors!” is a truism that actually holds up. But much of what we think we know about lightning is fiction. Here are some common myths, along with the facts that will keep you and your loved ones safe in a storm
·Myth #1 – Lightning never strikes twice in the same place.
Fact: Lightning often strikes the same place repeatedly, especially if it’s a tall, pointy, isolated object. The Empire State Building was once used as a lightning laboratory because it is hit nearly 25 times per year, and has been known to have been hit up to a dozen times during a single storm.
·Myth #2 – Lightning only strikes the tallest objects.
Fact: Lightning is indiscriminate and it can find you anywhere. Lightning may hit the ground instead of a tree, cars instead of nearby telephone poles, and parking lots instead of buildings.
·Myth #3 – If you're stuck in a thunderstorm, being under a tree is better than no shelter at all.
Fact: Sheltering under a tree is just about the worst thing you can do. If lightning does hit the tree, there’s the chance that a “ground charge” will spread out from the tree in all directions. Being underneath a tree is the second leading cause of lightning casualties.
·Myth #4 – If you don't see rain or clouds, you're safe.
Fact: Lightning often strikes more than three miles from the thunderstorm, far outside the rain or even the thunderstorm cloud. Though infrequent, “bolts from the blue” have been known to strike areas as distant as 10 miles from their thunderstorm origins, where the skies appear clear.
·Myth #5 – A car's rubber tires will protect you from lightning
Fact: True, being in a car will likely protect you. But most vehicles are actually safe because the metal roof and sides divert lightning around you—the rubber tires have little to do with keeping you safe. Convertibles, motorcycles, bikes, open shelled outdoor recreation vehicles and cars with plastic or fiberglass shells offer no lightning protection at all.
·Myth #6 – If you're outside in a storm, lie flat on the ground.
Fact: Lying flat on the ground makes you more vulnerable to electrocution, not less. Lightning generates potentially deadly electrical currents along the ground in all directions—by lying down, you're providing more potential points on your body to hit.
·Myth #7 – If you touch a lightning victim, you'll be electrocuted.
Fact: The human body doesn’t store electricity. It is perfectly safe to touch a lightning victim to give them first aid.
·Myth #8 – Wearing metal on your body attracts lightning.
Fact: The presence of metal makes very little difference in determining where lightning will strike. Height, pointy shape and isolation are the dominant factors in whether lightning will strike an object (including you). However, touching or being near metal objects, such as a fence, can be unsafe when thunderstorms are nearby. If lightning does happen to hit one area of the fence—even a long distance away—the metal can conduct the electricity and electrocute you.
·Myth #9 – A house will always keep you safe from lightning.
Fact: While a house is the safest place you can be during a storm, just going inside isn’t enough. You must avoid any conducting path leading outside, such as electrical appliances, wires, TV cables, plumbing, metal doors or metal window frames. Don’t stand near a window to watch the lightning. An inside room is generally safe, but a home equipped with a professionally installed lightning protection system is the safest shelter available
·Myth #10 – Surge suppressors can protect a home against lightning.
Fact: Surge arresters and suppressors are important components of a complete lightning protection system, but can do nothing to protect a structure against a direct lightning strike. These items must be installed in conjunction with a lightning protection system to provide whole house protection.
Have you ever had the feeling that lightning was about to strike? It was more than just a feeling. Oncoming lightning can give some noticeable signs before it's about to strike; you just need to know what to look for. Here's what you need to know.
1. You See Tall, Bright White Clouds
Tall, bright white clouds are "cumulonimbus clouds." These clouds may appear to be soft, fluffy, and nonthreatening, but that's only true when they appear in bright skies. If these clouds appear during a storm or in a grey sky, they could mean lightning.
2. You Can Hear the Thunder Approaching
When you see lightning, count the seconds until you hear the thunder. Keep doing this every time lightning strikes. You don't need to ensure you count in one second intervals; it's more important that you count consistently.
If the time is getting shorter, that means the storm is approaching and lightning is coming your way. If the lightning is heading your direction, you should immediately seek shelter.
3. You See Your Hair Standing on End or Feel Tingling
Just before lightning strikes, static energy is going to fill the air. If you look at your arms, you may see the hair on your arms standing on end. You may also feel a physical tingling sensation throughout your body, especially in your extremities. This is often the gut feeling that people get when they "sense" that something is impending.
If your hair is standing up, you may have only a few seconds to protect yourself from lightning.
4. You Taste Something Metallic
Though it may sound strange, you may taste something metallic in your mouth just before a lightning strike. Electrical stimulation in general can lead to a metallic taste, including electrical discharge from batteries. If you taste something metallic, you are already experiencing some form of electrical current, and you should immediately get into a safe area and out from under open sky.
5. You Smell the Scent of Ozone in the Air
Ozone, the smell after a rainstorm (often described as similar to the smell of chlorine), has an unmistakable scent. It often feels fresh or clean after a storm, but when it's during a storm, it could mean that a lightning strike is imminent.
The scent of ozone in the air is associated with electrical discharge overall. That means that the scent of ozone could also mean that lightning has already touched down in an area. Of course, this also means that the area itself could still be dangerous.
6. You Start to Get Dizzy or Sweat
Once you start to get dizzy or sweat, a lightning strike is imminent. This means that you should immediately get under cover and away from any large, metal objects as soon as possible. The feeling of dizziness and sweating is caused by the electrical charge interfering with your nervous system and heating your body, as hearts run on electrical current.
7. You Can Hear Vibrating, Buzzing, or Crackling
Even if you aren't feeling anything electrical, you may be able to hear a buzzing, cracking, or vibrating in the metallic objects near you. Under no circumstances should you try to touch these objects. Make sure you stay far away, because electricity can arc towards you even if you aren't touching the items. Electrical hums and buzzing may intensify as lightning approaches, and it should only happen once lightning is within a few seconds of striking.
Of course, even when you know lightning will strike, you still need to do something about it. Not only do you need to go to a safe place when it's happening, but you may want to take proactive measures to protect your property. Visit Universal Lightning Protection Services today to find out more.
© UPLS 2022