Author Topic: lightning protection  (Read 1216 times)

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machinemaker

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lightning protection
« on: July 13, 2021, 04:30:05 PM »
I had to stop work outside this afternoon due to the nearly daily thunderstorms this week. My question is what do you do for lightning protection with a tower? The tower itself will be fairly well-grounded with the base and guys, what else should I be thinking about?
machine maker

Scruff

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Re: lightning protection
« Reply #1 on: July 13, 2021, 05:57:28 PM »
The dielectric strength of your conductor insulators routed to your house from the wand or Arc Fault Interrupt response on same conductors.

Mary B

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Re: lightning protection
« Reply #2 on: July 15, 2021, 01:41:19 PM »
I had to stop work outside this afternoon due to the nearly daily thunderstorms this week. My question is what do you do for lightning protection with a tower? The tower itself will be fairly well-grounded with the base and guys, what else should I be thinking about?
machine maker

Coming from the ham radio side of towers and LOT of very expensive connected equipment...

Tower ground needs to be multiple 8' ground rods all bonded in a ray pattern coming from the base of the tower, 1 rod at the tower then at least 4 and preferably 8 more going out in 4 directions with the rods spaced 16 feet apart(12 for 6' ground rods, 8' for 4' and double the number needed...).

all wires coming down the tower need to be grounded at the base via a lightning arrestor like this one https://www.altestore.com/store/enclosures-electrical-safety/lightning-protection/delta-la302dc-dc-lightning-arrestor-500v-p473/

You should also have a lightning entrance panel with another one of the arrestors and a ground rod under it with more rods spaced out and bonded together and bonded to the tower if it is within ~50 feet of the house/shop/garage where the wind power enters.

I use Cadweld and #2 bare copper between each rod, once the wire is bonded the rod can be driven below the surface(make a map of where they are! if any utility digging is needed they need to know this!) and the wires can be pushed into slits in the grass to get them below lawnmower reach. Yes this is a lot of hard work! Some have made cable plows to pull behind ATV's to bury the ground wires, makes the job go a lot faster.

Cadweld is available from many sources, I use these guys because I buy enough gear from them to get discounts! Buy the kit to fit your ground rod and wires, they make kits to bond multiple wires to one rod. This is exothermic welding and CAN light the lawn on fire if it is dry enough. Same for your house! I used a welding blanket between the rod and house to control sparks and wet the ground down to prevent any fires.

https://www.dxengineering.com/search/department/grounding-and-lightning-protection/product-line/erico-cadweld-one-shot-wire-to-ground-rod-clamps/part-type/wire-to-ground-rod-clamps?fr=part-type&SortBy=BestKeywordMatch&SortOrder=Ascending&autoview=SKU&keyword=grounding

The key to lightning protection is a single point ground system your utility ground and any lightning protection grounds should all be part of one system. From where my AC power enters the house I have 1 ground rod, then 16 feet away a second ground rod, then it connects to the tower ground system.

My solar panels are 80 feet from the house and they have their own ground system of 9 rods all bonded together, it is not practical to run a rod every 16 feet for that distance, plus it can actually cause problems due to the length of wire between ground points. That wire can pick up energy during a strike... so I have 2 separate ground systems with arrestors at each end. It ha survived a direct lightning strike with zero damage in my house.

My house entrance panel, with ham radio I have a LOT of wires entering that can carry lightning energy. ALL of them are protected. The aluminum plate in the back is a ground plane with bolts down each side for me to connect lightning arrestors to. Copper would have been better but I was short on cash and a hunk of copper plate that size would have ran me $70! Yes that is a re-purposed cooler! It has arc marks inside from that lightning hit as energy dissipated. I was sitting 6 feet form where wires enter the house in the lower right corner and it scared the crap out of me and was rather LOUD. The main house ground point is right under it.






MagnetJuice

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Re: lightning protection
« Reply #3 on: July 15, 2021, 11:57:13 PM »
Nice post, Mary. Thank you.

Ed
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Scruff

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Re: lightning protection
« Reply #4 on: July 18, 2021, 06:19:15 PM »
Second that.

Ireland's great at mediocrity.
My latitude is my lightning protection.

No solar panel shattering hail storms.
No spiders that can kill ya.
No creatures at all in the food chain above humans.
Bitey insects are pretty few.

Sure does rain a lot tho...

Mary's solution reminds me of this.


Mary B

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Re: lightning protection
« Reply #5 on: July 19, 2021, 02:11:14 PM »
LOL That is NEC recommended grounding! Add in tornadoes, 90+mph straight line winds for fun, packs of coydogs(coyote/dog mix) that are attacking people(shot one last week! No I won't share a pic, a 123 grain V-max kinda made a mess)...