Lightning Protection

ToddDubya

ToddDubya

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According to my searching, lightning protection has been talked about here but never actually discussed. All I've found so far is: you should have lightning protection and here are some links to ARRL.

I'm looking to put up a 30' aluminum mast in my yard. Right now I'm planning on an inverted vee for HF and a ground plane for 2m. While I have no plans to expand the antenna farm, I also know myself well enough to know I probably will. But that's another topic.

While planning out what cables I need to buy it dawned on me I should have some lightning arrestors, one for each antenna. I don't know a whole lot about them and my searching has pretty much told me that I can spend as much or little as I want. What I can't tell is what the real practical difference is between a $20 arrestor and a $65 arrestor. Yeah, the pricier ones will handle more current but I think a lightning strike carries a *couple* more amps than the surge protector is sized for. If they're both undersized I'd rather spend $40 than $130.

My current plan is to run both antennas to lightning protectors that will be bonded via braided ground strap to a ground rod near the mast. I'll also tie that ground to a window feed-thru panel and in to my equipment.

TL:DR

So what do you guys run? Photos would be helpful to see how you have it all connected up. What's your advice on lightning arrestors? I'm sure I'm not the only guy out here who's uncertain about lightning protection.
 
I will tell you that nothing stops lightning. Most of those suppressors will blow apart if hit. A better path to ground from the mast than the one through your equipment is the best way to minimize the chance of damage
 
Chet is right; a direct hit will destroy everything within reach. The suppressors are for near misses. A bolt creates a tremendous amount of EMI and a close one will be picked up by your antenna and blow out your radio's front end. I think it was Zappa that described unscrewing the coax from his radio and laying it on a steam radiator. When lightning struck close by there was so much on the cable that the connector would arc through the radiators paint.

General advice:
1) Put a ground rod close to your shack and just before the coax enters the building. Some people with shacks in the basement drill holes in the basement floor to make it really close(that's over the top). Run heavy flat braid or copper pipe from the ground rod to your shack. My strap to the ground rod is pretty short (12' long). I have my suppressors close to the shack, not the rods. Opinions vary on where to put them.
2) Someday when you have a tower on a concrete pad, put 2-4 ground rods close to the pad and ground the tower to them. Otherwise a direct hit might blow out your concrete.
3) If you know lightning is coming, disconnect your antenna(s) from the radio(s). Not with a rotary antenna switch, but unscrew the cables. It might save you in the unlikely event of a direct hit.
 
So arrestors for nearby lightning and grounding the mast for direct hits? Is there a rule of thumb for sizing an arrestor?

Between braided straps to a ground rod and an aluminum mast in/on the ground I think I should be covered (within reason) from a direct strike standpoint. The mast will likely be stabilized by a brace to the house, but otherwise not in contact (i.e. not strapped to the chimney and sitting on the roof).

I expect I'll disconnect my radio when I'm not using it, mostly because my "shack" will also be my "dining room". But I'd like to be covered for those times when I forget or whatever. Obviously an air gap is the best protection.

Thanks for the feedback, guys.
 
n1bsbri said:
There's a lot of information on the ARRL website / technical services. Try here for starters:

Lightning Protection

ETA: make sure you bond any ground rods and connections you add to your service entrance ground. For some reason a lot of hams don't do this.
Click to expand...

Is that to eliminate ground loops? If I use my service ground for my equipment and the "new" ground rod solely for antenna protection, I think that'll eliminate ground loops, since the antenna ground rod would not be part of the normal electrical path.
 
ToddDubya said:
Is that to eliminate ground loops? If I use my service ground for my equipment and the "new" ground rod solely for antenna protection, I think that'll eliminate ground loops, since the antenna ground rod would not be part of the normal electrical path.
Click to expand...

You end up with a voltage differential between the two grounds, which will probably be expressed across your equipment. If the equipment has a 3-wire AC cord, it has a safety ground which is wired back to your service entrance. The antenna shield is bonded to the "other" ground. When there is a surge, the voltage differential is resolved across your $1200 HF radio. Not nice. Also not safe.
 
ToddDubya said:
So arrestors for nearby lightning and grounding the mast for direct hits? Is there a rule of thumb for sizing an arrestor?
Click to expand...
The arrestors "hard ground" the shield of the coax and have a gas discharge tube (spark gap) between the coax center and shield. So like the tower, the coax shield is directly grouned.

But, read the ARRL stuff. I might be a little rusty on this.
 
n1bsbri said:
You end up with a voltage differential between the two grounds, which will probably be expressed across your equipment. If the equipment has a 3-wire AC cord, it has a safety ground which is wired back to your service entrance. The antenna shield is bonded to the "other" ground. When there is a surge, the voltage differential is resolved across your $1200 HF radio. Not nice. Also not safe.
Click to expand...

Hmm, good point. I'll look tonight at how to best tie the two ground rods together. They'll be about 30' apart, around a corner.
 
I went to a friends house several years ago that took a direct hit somewhere on the house. It melted the top off the ground rod. Lightning is very powerful.
As someone above mentioned,common point grounding is the key to protecting your equipment. Multiple ground points make your equipment the fuse.
 
I rolled by Home Cheapo last night to see what they had for grounding equipment. I was able to find 8' ground rods which I'm fairly certain I won't be able to pound into my rocky ground. My property was built up with the fill from the rest of the neighborhood so digging holes is nearly impossible due to the size/quantity of rocks.

I should have bought it to at least try and pound in, but I was thinking of cutting it in half and using one at the mast and another halfway between the mast and the service ground rod, all bonded together with 2# wire (which I didn't see at Home Cheapo, but I'm sure it's around somewhere). I know code says it has to be 8', so there's that. [thinking]
 
Pound the rod in as far as you can and cut off the remainder. Code only applies to your service's ground rod. For your shack, just do the best you can. Our club uses 4' rods for their Field Day set-up.

I taped a 1/2" plastic hose to my ground rod, connected it to my garden hose and used it as a water drill to see how far down the first big rock was. It took a couple trys before it went down 4' without hitting something so I took the hose off and pounded the rod into that hole. I got all 8' down.

My natural gas enters the house on the same side as my shack so I called Dig Safe before pounding the rod in.
 
A Harger copper ground bar bolted to your foundation where the cables entrance is. A ground rod driven in as far as you can go and connected with some 4 or 6 AWG wire back to the ground bar. Then use PolyPhaser lightning arrestors, they have been the standard in the communication tower industry for decades, bolted to the ground bar to connect your cables to before they go into the house. This is what I have but I still disconnect my cables when a thunderstorm is predicted.

If you really want to read up on station grounding get yourself a copy of the Motorola R56 manual. It is what the industry uses as a reference manual for grounding on communication sites.

Near-Fest is in a couple of weeks so you might be able to pick up some stuff there.
 
ToddDubya said:
I rolled by Home Cheapo last night to see what they had for grounding equipment. I was able to find 8' ground rods which I'm fairly certain I won't be able to pound into my rocky ground. My property was built up with the fill from the rest of the neighborhood so digging holes is nearly impossible due to the size/quantity of rocks.

I should have bought it to at least try and pound in, but I was thinking of cutting it in half and using one at the mast and another halfway between the mast and the service ground rod, all bonded together with 2# wire (which I didn't see at Home Cheapo, but I'm sure it's around somewhere). I know code says it has to be 8', so there's that. [thinking]
Click to expand...

Home Depot also has jackhammers with the bit/attachment for driving grounding rods. Might be worth the rental, as getting the full 8' of ground engagement does help.
 
Near-Fest is very big. Unfortunately it runs Friday through Saturday pm so lots of the good stuff is gone by Saturday a.m. I've only gone on Saturdays and still have scored good stuff cheap. Even if you don't buy, it's an experience.
 
neum69 said:
I've not been to this. Is it worthwhile?
Click to expand...

It's an experience. Get there early on Friday if you can for the best selection. I believe gates open at 9am. $10 general admission. Keep an eye on the weather, I never go if it rains there because too many sellers that leave their stuff out in the weather and you never know what the condition of the equipment is that you are buying at that point.
 
Thanks, guys for the near-fest info. Will try to go. OP, let us know what you end up doing for your lightning arrest setup.
 


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