Effective Lightning Protection Methods

Try a google search for surge protectors.

A Faraday cage might block the effects of external electric fields, but penetration of the cage by a conductor provides a path for surges impressed on the conductor to reach equipment within the cage. In essence, your electrical supply is carrying the lightning surges from outside into your cage and damaging your equipment. You need surge arresters appropriately installed at the proper points in your system to protect your equipment. That would probably be at the electrical service entrance into your building. Seek qualified help in doing the selection and installation of the surge protection!

Also, make sure your equipment and electrical system grounding is done properly, per all applicable codes & standards.

Hi

Lightning protection design

1- Location where is this

2- do risk assesment what you really need

3- select the suitable method

4- Applicable standards NEC BS IEC VDE

regards

Frankly speaking there are no effective methods of protection against lightning strikes. Lightning itself is a phenomena which is as unpredictable as it is baffling. I am sure you are having the conventional system of lightning rod on top of the building which is connected to downcomers i.e. earth strips which run down the building at a number of places around the building and are connected to earth pits at the base of the building. You may check whether these downcomers are as straight as possible and do not have sharp bends; are not disjointed or damaged.

The most effective way of tackling your problem is remove all the earth connections of the IT equipment and have a separate / isolated earthing system for your equipment. I think you are using the same earthing network of the building for earthing your equipment which is badly affecting your system.

BB Raina

I strongly disagree with this suggession to have an "isolated" earthing system for IT Equipment. Going by IEEE 1100 (Recommended Practice for Powering & Grounding Sensitive Electronic Equipment) - such a practice of having isolated earthing system for IT equipment is not permitted.

To quote from IEEE 1100 - Clause 9.10.12.2: "The use of any separate, isolated, insulated, dedicated, clean, quite, signal, computer, electronic or other such IMPROPER form of earth grounding electrodes for use as a point of connection of the equipment grounding conductor is not permitted". (Please note that the Standard has termed such isolated earthing as IMPROPER).

Also, vide IEC 60364-7-707, "the use of independent, "isolated" earth electrodes for computer or electronic systems is not recommended/permitted".

Now, would you like to go againt these Standards?

What could be the reasons for such a recommendation from IEEE1100? Why is it not permitted? Would be grateful if you can enlighten us on this because now-a-days insulated earthing Intrumentation/ Electronic system has gained popularity.

BB Raina

The use of separate, isolated grounds for such things as IT or medical equipment, while promoted by some manufacturers, is often the cause of more problems than it solves. It can result in potential differences between supposedly "equipotential" equipment (dangerous touch potentials can kill!), ground loops, power quality problems with harmonics and noise, and other troublesome issues. If an electrical system is properly grounded and bonded per accepted standards and codes (IEEE, NEC, etc.) and with properly engineered and sized protective equipment (surge arresters, etc.), you will avoid many problems that plague electrical installations.

Do you have the incoming Outside Plant Communications cable protected?

http://www.adc.com/us/en/Library/Techpub/81608.pdf?refer=Library&C=Data_Connectivity

Please follow IEC 62305. Even if you install a faraday cage external to the building there are chances of equipment getting damaged due to method of routing down conductors near sensitive areas,incorporating loops,inducing voltage etc.Sometimes it is advised to enclose rooms with sensitive equipment in a separate faraday cage.You should check earthing and surge protection of those equipment too.Or call an specialist.

If the path of the lightning discharge goes through anything that can cause a difference of potential between different grounds, you can cause serious ground potential differences between connected computers. Ethernet actually uses the earth ground connection on computers as one of the signals. It takes very small amounts of resistance to cause voltages high enough to blow these interfaces and the computer circuits they are installed inside. Current from a lightning strike can average 100,000 amps and sometimes be as high as 300,000. If your mentioned Faraday cage has ANY connections to any of these earth grounds, you're going to blow stuff fairly often from grounds. Even rebar grids in concrete floors are usually not adequate to handle the big strikes.

Almost all digital equipment power supplies are switch type which can allow transients to feed through the power supply into the equipment rather easily,causing considerable damage to equipment if your power lines are happening to act like antennas. If your Faraday cage is good enough, you're probably not seeing damage of this type. A lot of very good EMI RFI surge protectors would take care of this type of problem if it does exist.

If you can define the failures more specifically, this might allow a better guess to the actual failure mode you are experiencing