Lightning arrestor installation place

Hello Asitha

You don't list your Location or Country, which you can easily do in your Profile, and would be especially helpful to people replying to a Question such as yours.

If the water tower is built of reinforced concrete, it is very important to fit a proper lightning arrester system.

I have not seen the design of water tower you are thinking of, or are building, and a diagram or plan/picture here, with some dimensions would be helpful.

The Ground resistance at the base of the tower is important that this be lowered as much as possible, and, once again, I do not know the nature of the ground where you are writing about, but this is normally done by an Earth Mat, with a ring of circumferentially connected and driven Earth Rods..

Thus I can only give general advice, until some missing details are supplied.

General:

The "early Streamer" device emits streams of charged ions from the upwards facing pointed electrode tips.

Before the main discharge of lightning, the charged cloud emits a ground-seeking streamer of voltage which may exist for several minutes, extending itself towards the ground, or any object which is higher, even though a poor conductor, helped by rain, should that be falling at the time.

The downwards travelling streamer eventually makes near contact with the ground, ionising the air during that travel downwards.

This is why at times, people have had the hair stand up on their head, because of the higher than normal Voltage field (Normal Planetary electrostatic field is approximately 1000 Volts per Metre, vertically for some 20,000 feet) - and if you ever have your hair stand on end, with a large cloud overhead, you may have less than a second to fall flat, to minimise a lightning shock to yourself.

When that downwards travelling streamer makes full contact with the ground, or grounded object, because the ionised air is conductive, the main discharge happens immediately, perhaps several million Amperes at 20,000,000 Volts or more = Huge energy transport in a few seconds.

The air outside the discharge cloud is instantly heated to plasma state, perhaps 1,000,000 Degrees Celsius or more, and the rapid expansion causes the Thunder sound.

If you are very close to a lightning strike, a few Metres away, and are not injured, you find that you never heard the thunder, but you heard the discharge, which has the typical sound of "tearing calico", and having been in that situation several times during a dry thunderstorm, before the heavy raindrops started falling, it is rather a frightening sound.

Induced charges are minimised, by all reinforcing steel having welded joints, and being properly bonded to the Earth Mat, at Tower base.

Building Protection (Your Water Tower).

The Earth Mat is welded copper conductors, in a 600mm x 600mm square grid form, cross-sectional area of conductors being 1 inch diameter or equivalent, with driven hot dip galvanised/copper/stainless steel electrodes, dependent on local soil corrosiveness.

All joints are welded and crimped/bolted/riveted, dependent on the type of mat conductor being used.

1. The Earth Mat distance extended outwards from the tower base is determined by:
2. Annual number of Lightning days in the area
3. Height of Tower
4. Resistance of soil
5. Whether other buildings are located in the vicinity.
6. Other factors as advised
   

Flat electrical busbar grade Copper strip 100mm wide x 6mm thick is run around 4 sides of the tower, upwards all joints welded using "Silfos" or similar welding wire. Each joint is also bolted or riveted before welding.

The vertical strips run to the top of the tower, as straight as possible, with no sharp corners, and if there is a single point higher than any other, all go there and are connected together, welded + riveted/bolted.

The "Streamer device" normally fits at the tower top, to radiate upwards the ionised streamers.

The energy contained in the average lightning strike may be enough (if carefully and instantly capable of being safely stored), to meet the demands of a large city for several months.

That's a short summary, and trust it assists you.

Should you wish further please

Kind Regards....

Hello again, Asitha

for your valued reply.

What should happen, is that the water supply pipelines to/from the water tower should be Insulating pipes: Polythene, Cross-linked Polythene, or HDPVC, etc.

The pipes must be metal within the bottom of the water tower foundation, and those Metal pipes MUST BE ELECTRICALLY BONDED ONLY at the Earth Mat, by both clamps and welding.

The Pipelines to/from the tower out past the Earth Mat, should once again be Polythene, Cross-linked Polythene, or HDPVC (High Density PVC),for at least 100 Metres, or more, dependent on soil conditions.

The purpose of the insulating material used for all pipes vertically in the tower, is to ensure lightning discharge does not use the pipes as a conductor, and the earthed portion of the pipeline at Earth Mat level, then the long insulated pipe/s away from the Earth Mat, ensures any induced voltage passes into the Earth Mat, thence to the several/many, driven Earth Electrodes.

If the tower vertical pipes are inside the reinforced cage of reinforcing steel, they are effectively within a "Faraday Cage", and there should be minimal induction from a lighning strike to the tower, if proper lightning protection is installed.

Please have a look at this below, as they will certainly have much local expertise:

<".... Refer: http://news.oneindia.in/2006/04/26/ne-most-lightning-prone-zone-in-world-1146051633.html

Wednesday, April 26 2006 16:57 (IST)

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Guwahati, Apr 26 (UNI) Nature has endowed North East India with beauty, and has also chosen it as its favourite destination to display its fireworks.

NE region enjoys the distinction of being among the regions with the highest lightning density, with the Brahmaputra Valley having the world's highest average of lightning days.

This was stated by Deputy Director General of the Regional Meteorological Centre, Guwahati, D Chakrabarty on the opening day of a two-day National Workshop on Lightning Protection here today.

The workshop has been organised by The Energy and Resources Institute (TERI), in collaboration with South Asian Lightning Information and Resources Centre, Sri Lanka. It is being supported by Union Department of Science and Technology and MTL India Limited.

Against a world average of 70-80 days of lightning days annually, 121 days are recorded in NE alone.

As per data available since 1959, 119 lightning or thunderstorm days have been recorded in Guwahati alone. During the same time, Tezpur accounted for 121 days and Dibrugarh for 113 days. Similarly, Dhubri reported 89 lightning days, Silchar 77 days, Imphal 56 days, Pasighat 34 days and North Lakhimpur 69 days.

Dr Chakrabarty informed that three deaths due to lightning were reported from Asom and Meghalaya each last year, while Tripura had five such deaths. About five deaths have been reported from Asom in the current year, he added.

He maintained that in the absence of organised mapping of lightning incidents in the region, the total deaths and other damages to property could not be ascertained. He added that the death toll would rise if proper survey was undertaken. ....">

Trust that assists you further.

Kind Regards....