Product News | Services | Website Design | Tips & Tools | News | Jobs | Company Login | Add Your Company | About EngNet

Impact assessment of a lightning strike to a business site

An exercise seldom undertaken by the management of small and large business alike in Southern Africa is the impact assessment of a lightning strike to the business premises. The cost implications of down-sizing, outsourcing, franchising, brand-building, employee motivation and globalisation on the internet top the agenda at the Monday morning management meeting. The negative impact of equipment theft, warehouse fires, bad debts and other potential business-damaging events are well understood and insured against. With so many important issues to address, it is not surprising that the almost obscure event of a direct lightning strike to your business premises is largely ignored...until it happens, that is! The truth of the matter is that to a business, the damage that a lightning strike is able to inflict could be crippling in a multitude of unforeseen ways. The good news is that it is largely preventable. This article will outline the importance of conducting a simple impact assessment and investigate methods of preventing damage to the assets vital to your business.

Like any good business decision, the first thing that is necessary is to identify the risk and put a well thought out plan into place to achieve the desired results. This could be done using the following steps:

• Quantify the risk of a lightning strike to your business premises
• Identify vital equipment which could be damaged in the event of such a strike
• Accurately estimate the impact in terms of both cost and image that downtime due to a lightning strike could have on your business
• Develop and implement a strategy to limit the impact of such a strike
• Schedule a future reassessment to ensure that your strategy keeps pace with the growth of your company and maintenance is not neglected

We shall now look at how each step of the impact assessment is performed.

Quantifying the risk to your building

Fortunately, a fair amount of academic research has been undertaken in this field so that it becomes possible to put a number to your likelihood of being the victim of lightning damage. Lightning damage may occur either as a result of a direct lightning strike to the building or, more subtly and more commonly, as a result of the induced effects of a lightning strike some distance away. Lightning which strikes kilometres away may cause damaging electrical surges which travel long distances on power and telecommunications lines. Although a proper detailed risk analysis* is outside of the scope of this article, there are some simple calculations which may be performed and basic reasoning which may be employed. Firstly, look up the lightning ground-flash density (LGD) of your area. Lightning ground flash density is simply a number which represents the average number of direct lightning strikes to a square kilometre of your area in one year. The LGD for Johannesburg is approximately 7 strikes/square km/year while Durban and Cape Town drop down to approximately 3 and 1 strikes/square km/year respectively, indicating a significantly lower risk in these two areas. The next step is to investigate the geography of your area and use the rules outlined in the standards (SABS IEC 91024-1) to work out what percentage of those strikes to your area are likely to terminate on your building and what percentage are likely to cause induced surges which may damage equipment connected to power or telecommunications cables in your office. Should the standards be too technical or if you simply don’t have the time or inclination, earthing and lightning protection companies will perform the service at relatively inexpensive rates or even free of charge as it leads to further business for them. Quantifying the risk will allow you to make an educated financial decision about the lightning protection measures which need to be employed in your business.

Adding up the cost of lightning damage

Once the lightning risk has been determined, the next step is to calculate the costs should lightning damage occur. These costs may be split into two types, direct and indirect costs:

Direct costs are incurred when lightning damages equipment, buildings and causes lost productivity. Common equipment fatalities in the business environment include:

• computers and peripheral equipment such as scanners and printers
• modems
• network equipment
• fax machines
• alarm systems
• electric fence energisers
• CCTV cameras and equipment
• electric gate motors
• intercom systems
• telephones
• PABX’s
• Specialised electronic equipment unique to your type of business

Additional direct costs include:

• Repairs to damaged wiring and building superstructure
• Lost productivity resulting in lost income

A commonly heard response during this exercise is "My insurance will pay so it is of no real concern to me." This is only true in some cases as most insurers now state in their contract that they will only cover the eventuality of lightning damage provided that adequate lightning protection systems were in place. Lost productivity is also a direct cost which few businesses are covered for. The figure you have arrived at for your business represents an estimate of the immediate cost which you will probably incur every X years where X is the result of your lightning risk analysis outlined above. Not so easy to quantify, however, are the indirect costs.

Indirect costs represent losses to the business in ways which are not so easy to put a figure to. Some of these may include:

• Downtime of the phone and PABX system - most businesses rely heavily on their incoming phone lines as a source of new business and client contact. Phone downtime loses customers and damages service reputations.
• Downtime of computer systems and networks - once again, if your emails go unanswered, your website is unavailable and your staff are sitting helplessly behind blank screens, customers and reputations are lost
• Lost data - a massive hidden cost to any company operating computers (who isn’t?). Not only is the information lost but if no adequate back-up strategy is in place, months or even years of work may be lost as well.
• Lost productivity may also be classed as an indirect cost as late deliveries also ruin reputations. If you operate expensive imported machines where spares and repair expertise are not freely available, your company should be especially wary of this point
• Breach of office security - When the electric fence, CCTV cameras, electric gates and alarm system are out of action, your premises are exposed to a high security risk
• Health - although rare when compared to the frequent damage of sensitive electronics, lightning strikes sometimes claim human victims which is unforgivable when it is easily preventable.

Developing and implementing a lightning protection strategy

If the preceding steps have been investigated, you should have a decent idea of the impact of the lightning threat on your business. The next step is to analyse what you know and put a simple but effective strategy into place in order to deal with the threat. Such a strategy is proposed below:

• Get a reputable and qualified consultant to check the earthing system of your premises. The earthing system is vital to both general electrical safety and the correct operation of lightning surge protectors. Many companies will do this testing free of charge in exchange for the contract to supply earthing or surge protection equipment.
• Install decent surge protection on all of your valuable equipment. Something to note about surge protection devices is that, like any product, you get the poor quality, badly designed and the decent products. Finding out which is which may be difficult but asking for properly tested, SABS approved equipment is a good start. Another good strategy is to ask for advice from the technical department of a number of companies and compare the different answers. You could also contact the local university, the SABS or the CSIR or equivalent bodies and ask the advice of the electrical engineering departments. This technique will help you to isolate the competent companies. In general, the cost of installing decent surge protection will be a fraction of the cost of the equipment being protected and should be viewed as a vital form of physical insurance. Remember, most insurance companies will not cover equipment damaged by a lightning strike unless lightning protection devices are installed.
• If the risk analysis indicates that the expected number of direct lightning strikes is high due to your geographical situation, you should also consider installing an external lightning protection system if one is not already installed. This system comprises a series of interconnected conductors running from your buildings roof, down the walls and into an earthing system. An external system of this type is designed to divert the lightning currents safely to earth on the outside of the building and prevents damage to the superstructure, dangerous side-flashes and touch-potentials inside the building and minimises the risk of damage to equipment. An external lightning protection system is not a substitute for surge protection devices but is rather an additional and vital level of protection which complements the operation of the surge protection and decreases the overall risk of lightning damage to your building as the path of the lightning current is controlled and diverted directly to earth.
• Finally, a maintenance strategy should be put into place to check that the earthing system and surge protection devices remain in good working order. Earthing systems degrade with time due to corrosion, theft (they comprise mostly copper!) and accidental disconnection during non-related electrical work. They should be checked on a regular basis. Surge protection devices degrade with use like any other physical product and should be maintained and replaced accordingly. Some products have failure indicators built in which visibly indicate failure. Maintenance strategy should include the checking of all surge protection devices after big storms, checking the devices and the earthing system after the summer lightning season and possibly the replacement of all surge protection every 1-3 years regardless of visible condition.

Conclusions

The negative effects of direct and indirect lightning strikes to a business can be minimised. In fact a lightning strike is one of the only forms of natural disaster in which no damage to person or property is necessary, provided the correct technology and strategy are employed beforehand. At the end of the day, the risk of damage must be weighed up against the cost of installing and maintaining a lightning protection system and each business requires a unique strategy to combat this threat.

Information Supplied By:

Contact:	Company:
Grant Walliser, MSc (Eng)	Kuell Lighting Protection
Click here for Company Profile and Contact Details