lightning protection

[billd766]

I want to build a weather station at home and the anemometer will be mounted on a steel pole about 11 metres up to get it over the trees and the roofline of the house.

We live in the country and when the thunderstorms are around there is also a lot of lightning although the house has not been hit. About 500 metres away there is a ToT tower about 25 to 30 metres tall which has been hit a few time (it knocks out my internet).

I am not sure if I need to put a lightning rod extending 1 or 2 metres above my anemometer and run a fairly thick cable down the pole to a ground rod buried 2 or 3 metres into the ground. The system has no physical connection to the house at all and all the info is wirelessed across.

I can get the steel pole up here in rural Thailand and I will be using galvanised or stainless steel 3mm wire for support stays. Galvo turnbuckles and anchor bolts etc.

I have no idea where to find a lightning pole though. Does anyone have any ideas?

I found an old archived thread from TVF back in 2008

http://www.thaivisa.com/forum/topic/211667-lightning-strike/page-2

[eyecatcher]

The steel pole is your answer.

Its obviously earthed by means of a foundation to it.

Why are you looking for anything more.

At the same time you can earth your house with it and save yourself 1k bt buying a copper rod.

Sounds flippant but true .

[Longtooth]

The steel pole is your answer.

Its obviously earthed by means of a foundation to it.

Why are you looking for anything more.

At the same time you can earth your house with it and save yourself 1k bt buying a copper rod.

Sounds flippant but true .

Well, I like the original poster's idea better. Lightning could travel down one of the guy cables and burn it in two (or vaporize it) If you have the money just use the long (2 meter?) copper clad steel ground rods they sell at every home improvement store as your upright rod and maybe three in a triangle with 2 or 3 foot separation (length of the sides of the triangle arrangement) around or next to the base of the pole (triad ground) linked with a bare copper cable about the size of your little finger ought to do it. Make a complete circle with the cable on the triad ground, and link the top rod to the assembled triad ground. A continuous cable with no splices is best. Use the ground clamps that they use on the rods same as a house system ground. Make nice round bends in the cable, not sharp corners. Should work. Whether it would protect the electronics in your mast mounted anamometer is another question. Maybe, but probably not.

[billd766]

The steel pole is your answer.

Its obviously earthed by means of a foundation to it.

Why are you looking for anything more.

At the same time you can earth your house with it and save yourself 1k bt buying a copper rod.

Sounds flippant but true .

The house is earthed anyway and the steel pole will be in the front garden some 20 metres from the house.

My concern was for the anemometer etc mounted on the pole.

[billd766]

The steel pole is your answer.

Its obviously earthed by means of a foundation to it.

Why are you looking for anything more.

At the same time you can earth your house with it and save yourself 1k bt buying a copper rod.

Sounds flippant but true .

Well, I like the original poster's idea better. Lightning could travel down one of the guy cables and burn it in two (or vaporize it) If you have the money just use the long (2 meter?) copper clad steel ground rods they sell at every home improvement store as your upright rod and maybe three in a triangle with 2 or 3 foot separation (length of the sides of the triangle arrangement) around or next to the base of the pole (triad ground) linked with a bare copper cable about the size of your little finger ought to do it. Make a complete circle with the cable on the triad ground, and link the top rod to the assembled triad ground. A continuous cable with no splices is best. Use the ground clamps that they use on the rods same as a house system ground. Make nice round bends in the cable, not sharp corners. Should work. Whether it would protect the electronics in your mast mounted anamometer is another question. Maybe, but probably not.

Many years ago I was working for Motorola building mobile phone base stations and we did a one day course on grounding. Perhaps I should have stayed awake and also kept my notes. That was in 1992 and about 30 countries ago.

[Pib]

I understand what you are looking for...you definitely want a lightning rod protruding above the support pole/tower with ground wire going down the pole/tower to the grounding rod to ensure the lightning strike is shunted away from the pole and instruments on it...give a very low resistance path to follow. Same way that cell phone towers are protected.

I would think mounting a long copper grounding rod on top of the pole (a rod just like you drive in the ground would work) would work...get it at your local hardware store with some brackets to mount it to the top of the pole.

See this document.

lightning.pdf

[billd766]

I understand what you are looking for...you definitely want a lightning rod protruding above the support pole/tower with ground wire going down the pole/tower to the grounding rod to ensure the lightning strike is shunted away from the pole and instruments on it...give a very low resistance path to follow. Same way that cell phone towers are protected.

I would think mounting a long copper grounding rod on top of the pole (a rod just like you drive in the ground would work) would work...get it at your local hardware store with some brackets to mount it to the top of the pole.

See this document.

lightning.pdf

That is the sort of thing I was looking for though instead of a tower it will be a 6 metre length of 2 inch galvanised pipe connected to a 6 metre 1 inch pipe. I will fit a base plate on the foot and the anemometer will be set at about 11 metres AGL. There will be 4 wire stays 90 degrees apart which will hook on to some angle iron about 1 metre long which will be driven about 75 cm into the ground.

Longtooth above suggested extra ground rods and a ground ring too which IIRC was what we were taught about 24 years ago.

The foot of the pole will be bolted onto a small concrete slab and the cable supports will be concreted as well. I am hoping to get this set up in December during the dry season though I need a bit of damp in the ground to drive the stakes in.