Lightning Protection

Lightning Protection & Earthing: – Data Centre, Disaster Recovery Centre & Communication Centre.
What Is Lightning?

lightning protection image 1Lightning is a gigantic electric spark traveling between cloud and earth. Its energy level is difficult to comprehend. A single lightning flash may be on the order of 30 thousand amperes, 200 million volts, and will take place within 30 millionths of a second. We all know how short circuits in normal 15 amp house circuits can cause fires. Compare this with current and voltage values 2000 and 100,000 times that of the average circuit, respectively.

Lightning discharges are commonly referred to as “hot” or “cold” bolts. The difference is in the amount of power dissipated and the length of time it takes for this dissipation process. “Hot” bolts have higher current values and longer duration times, thus easily igniting combustible materials. “Cold” bolts on the other hand are characterized by low current values, high voltage and short duration times; thus producing the violent shattering effect.

Many Lightning flashes consist of multiple discharges, making this well-known natural phenomenon Nature’s Most Destructive Force.

Why A Lightning Protection System?

A properly designed and installed Lightning Protection System will protect lives and property against lightning damage. Such a system is designed to safely carry lightning currents to ground without damage to the protected structure.

A typical system will consist of air terminals (lightning rods) and ground terminals, which are connected together with low resistance conductors. These conductors are usually copper or aluminium as are other components of the Lightning Protection System. These metals and their alloys are specified not only for their electrical conductivity, but also for their corrosion resistance qualities. In addition to these basic items, Lightning Protection Codes require separately grounded systems to be bonded together as well as other metallic items that may provide a short circuit path between grounded items.

lightning protection image 2A properly designed Lightning Protection System will also take into consideration themyriad of electronic devices found in today’s Data Centre, Disaster Recovery Centre & Communication Centre. Transient voltage surge protection should be provided to guard against unwanted electrical disturbances from entering the structure via the electrical infrastructure, telephone infrastructure or data infrastructure.

All Data Centre, Disaster Recovery Centre & Communication Centre must implement lightning protection and earthing system to achieve maximum computer system and supporting equipment up time. Where centres have not implemented lightning protection and earthing system; data loses and corrupted files have been experienced, latent equipment failure is experienced [this failure is therefore not be associated with lightning] and equipment lose upon lightning disturbance [direct and/or indirect].

We design, supply and implement Lightning and Earthing protection system for Data Centre, Disaster Recovery Centre & Communication Centre, to protect Electrical system [i.e. Generator, UPS, etc], Computer Network system [i.e. LAN, VAN, etc], Telephonic system [i.e. PBX, Fax etc], Security system [i.e. CCTV, Access Control, Electric Fence etc], which complying with the relevant codes of practice and specifications.

Voltage Surges and Lightning Strikes

Voltage surges are momentary increases in the normal working voltage of a system. Sometimes referred to as ‘spikes’, ‘over voltages’ or ‘transients’, these surges affect power cables, data/telephone cables and instrumentation wiring, causing anything from data loss to the total destruction of equipment.

Lightning storms are on the increase globally and including the South Africa where more than 420,000 lightning strikes to ground were recorded in 2004.

Also on the increase is industry’s reliance on sensitive electronic instrumentation, computers and communication networks.

These make uneasy bedfellows as lightning-induced voltage surges damage or destroy delicate equipment with all the consequent costs associated with repairs, replacements and downtime.

Lightning Protection — Standards, Devices and Dangers

lightning protection image 3Two distinctive forms of lightning protection are look at one designed to protect the building structure and fabric, and the second to protect sensitive equipment inside the building.

The traditional mesh of copper stapes on roofs and walls and their associated ear

th rods, properly installed, protect the bricks and mortar but not, except to a very limited degree, electronic equipment within the building. The latter need protecting with ‘surge protection devices’ (SPDs).

SPDs do not protect equipment against direct lightning strikes. Their concern is to neutralise voltage surges on cables caused by inductive or resistive coupling from nearby lightning strikes.

In particular, SPDs should be fitted on the mains power supply lines and incoming data/signal cables to/from all critical sensitive equipment. Cables such as these and consequently any equipment associated with them are particularly at risk as they are partly installed outside the building where they are more vulnerable to the effects of nearby lightning strikes.

A strike within 1,000m of cables or buildings can induce surges up to 5 kV and 1.25 kA. Also at great risk are sites powered from overhead cables and /or telecommunication from overhead cables. Any direct lightning strikes to the power and or telecommunication network will travel along the cables to the detriment of any equipment powered by these since surges on mains power cables can rise to a level of more than 6 kV and 3 kA.

Lightning Activity and Voltage Surges

lightning protection image 4A direct lightning strike can cause an enormous amount of physical damage. However, the indirect effects from a nearby strike can also cause damage by inducing voltage surges onto mains and data cables.

Lightning-induced voltage surges are often described as a ‘secondary effect’ of lightning and there are three recognized means by which these surges are induced in mains or data/telecommunications cables, resistive coupling, inductive coupling and capacitive coupling.

Earthing

In general all earthing system needs to satisfy three requirements:

Lightning and short circuit

The earthing system must protect the occupants, prevent direct damage such as fire, flashover or explosions due to a direct lightning strike and overheating due to a short-circuit current.

Safety

The earthing system must conduct lightning and short-circuit currents without introducing intolerable step-voltage and touch-voltages.

Equipment protection and functionality

The earthing system must protect electronics by providing a low impedance path to interconnect equipment. Proper cable routing, zoning and shielding are importa

nt aspects and serve the purpose of preventing sources of disturbance from interfering with the operation of electrical equipment.

Economic Factors

Even after deciding that the risk of damage might be great enough to warrant surge protection, there is still the hurdle of cost to be considered. The cost of providing surge protection may appear prohibitive and/or nonessential.

However, the following need to be borne in mind:

Ninety percent of businesses and organisations are now reliant on their data network. If the data network is out of action, and/or the electrical system [i.e. Distribution Board, UPS, Generator Set] the business is paralysed. What is the cost to you of this “down-time”?

Restoring the data network and/or the electrical system may not simply be a matter of quickly replacing an item of hardware because:

  1. There may not be anyone with the required skills and confidence on site or available on short notice.
  2. Identifying a single faulty item of hardware is not always straightforward.
  3. There may be damage to more than one item, which will add to the difficulty of faultfinding.
  4. Replacement hardware may not be readily available.
  5. Hardware, even though it may be performing an invaluable job for your business, becomes obsolete and hard to replace, remarkably quickly.Can lost of data be guaranteed to be retrieved?

lightning protection image 247Most insurance companies are now advising surge protection implementation, and it has become a factor in premiums and the willingness to cover a claim in the event of damage.

In summary, hardware can be insured and replaced easily and quickly. Data is priceless; loss of data is more than an inconvenience.

Please contact us and tell us about your project. Give us the opportunity and we’ll provide you with the justification you need, to convince your management to take the next step – for TechNocRacy to be your preferred service provider.