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Author Topic: Shack lightning ground  (Read 3144 times)
N4NYY
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« on: June 04, 2012, 07:35:52 AM »

I am in the process of improving my lightning protection situation.

Right now, I have a bonded rod at the entrance point of the coaxes and bonded to the electrical panel rod.

My question, is this. My shack is in the basement about 5 or so feet below ground. I would like to add another ground rod into the concrete floor slab right outside the wall of my shack. Do I have to use a full 8' rod? I would have a difficult time trying to hammer it without hitting the floor joists overhead. Clearance is at a minimum.
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K5LXP
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« Reply #1 on: June 04, 2012, 08:10:14 AM »

The idea of lightning protection is to keep it out of your house.  Why invite it inside with an indoor ground rod?


Mark K5LXP
Albuquerque, NM
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N4NYY
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« Reply #2 on: June 04, 2012, 08:45:35 AM »

The idea of lightning protection is to keep it out of your house.  Why invite it inside with an indoor ground rod?


Mark K5LXP
Albuquerque, NM

Good point.
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KB3HG
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« Reply #3 on: June 04, 2012, 08:46:19 AM »

Yo Vinnie,
If you want to improve your shack ground, place another 8/10 footer outside and at least the length of the rod from the rod in the ground already. It's all about surface area, increase surface area decrease resistance. if you were to sink another rod in your basement, with the water table you have you would most likely create a current loop. A better ground in the basement. Definitely not a good idea. how many micro amps are needed to trip a GFI? you don't want to cause that kind of current loop. A ringing lightning stroke is going to put a fair potential in your basement. Bond with flat cu sheet stock ( low inductance) between rods and shack common point ground . 

Do you have a megger? They come in handy every now and again.

QST had some great grounding articles as well as lightning explanations a few years back and then one gentleman had an article about zinc sacrificial anodes.

Tom KB3hg
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N4NYY
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« Reply #4 on: June 04, 2012, 09:03:28 AM »

One other question.

Last year, I had natural gas installed to replace propane. The underground piping was a yellow plastic, but the mating at the meter is that plastic to metal. The meter was placed a few inches from my bond wire. Is this a concern? Should I re-route the bond wire away from the gas meter?
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AA4PB
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« Reply #5 on: June 04, 2012, 09:29:49 AM »

Most locations require a minimum 3-foot separation between gas service and electrical service components. Metal gas lines may not be used as an electrical bonding conductor, but metal gas line run to the inside of the home must be bonded to the electrical service ground to ensure that the conductive gas pipe cannot become energized and present a personnel hazzard.

It is best to check with your local code enforcement to see what their requirements are.
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N4NYY
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« Reply #6 on: June 04, 2012, 09:34:22 AM »

Quote
Most locations require a minimum 3-foot separation between gas service and electrical service components.

I will have to re-route the wire. The gas is well beyond 3 feet from the service panel.
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AA5WG
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« Reply #7 on: June 04, 2012, 04:43:32 PM »

Simple way to hold ground rod.

http://www.youtube.com/watch?v=0sLv4LLVPbA

Chuck
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N4NYY
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« Reply #8 on: June 04, 2012, 05:26:21 PM »

Chuck,

That is some rough soil! Mine is sandier and I hardly need a hammer that big.
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K1CJS
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« Reply #9 on: June 04, 2012, 06:11:16 PM »

I am in the process of improving my lightning protection situation.

Right now, I have a bonded rod at the entrance point of the coaxes and bonded to the electrical panel rod.

My question, is this. My shack is in the basement about 5 or so feet below ground. I would like to add another ground rod into the concrete floor slab right outside the wall of my shack. Do I have to use a full 8' rod? I would have a difficult time trying to hammer it without hitting the floor joists overhead. Clearance is at a minimum.

I would agree that keeping the lightning outside the house is the best course of action, but you're overlooking the obvious.  The ground rod in the basement does not have to be driven in straight down.  There is nothing wrong with driving it in at an angle, and if you insist on putting a ground rod in the basement floor, that is how you may have to do it.
« Last Edit: June 05, 2012, 09:03:14 AM by K1CJS » Logged
N4NYY
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« Reply #10 on: June 04, 2012, 06:42:28 PM »

I am in the process of improving my lightning protection situation.

Right now, I have a bonded rod at the entrance point of the coaxes and bonded to the electrical panel rod.

My question, is this. My shack is in the basement about 5 or so feet below ground. I would like to add another ground rod into the concrete floor slab right outside the wall of my shack. Do I have to use a full 8' rod? I would have a difficult time trying to hammer it without hitting the floor joists overhead. Clearance is at a minimum.

I would agree that keeping the lightning outside the house is the best course of action, but you're overlooking the obvious.  The ground rod in the basement does not have to be driven in straight down.  There is wrong with driving it in at an angle, and if you insist on putting a ground rod in the basement floor, that is how you may have to do it.

I am going to pass on a ground rod on the basement floor. Total brainfart on my part.
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K9KJM
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« Reply #11 on: June 04, 2012, 10:49:54 PM »

Quote: "I am going to pass on a ground rod on the basement floor. Total brainfart on my part"

GOOD!    As already pointed out, NEVER install a ground rod indoors!

Just install some more outdoors.   For best effectiveness in most soils, Space them about twice the distance apart as the depth. (Space 8 foot deep rods about 16 feet apart.)

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W5FYI
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« Reply #12 on: June 05, 2012, 07:58:58 AM »

Here's another thing to think about; I once heard that a direct lightning strike directed through a ground rod in very wet soil resulted in a steam explosion that caved in part of a basement wall. Since I cannot vouch for the veracity of this story, I only pass it along as "thought material."

Something I read on N1FN's home page this morning: "I just got lost in thought. It was unfamiliar territory."
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K1CJS
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« Reply #13 on: June 05, 2012, 09:06:40 AM »

...I once heard that a direct lightning strike directed through a ground rod in very wet soil resulted in a steam explosion that caved in part of a basement wall. Since I cannot vouch for the veracity of this story, I only pass it along as "thought material."...

I would tend to doubt that very much.  The only way you con get a steam 'explosion' is to have water concentrated in a confined area--some kind of container.  I wouldn't doubt that the ground was steaming--but I would doubt an explosion occured.
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N4NYY
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« Reply #14 on: June 08, 2012, 04:25:25 PM »

OK. Here what I have done so far, and what I am going to do.

I have bonded my shack ground rod with the electrical service ground rod with 4 gauge solid.

I have installed an Alphadelta antenna switch with surge protector, which grounds the center conductors when switched off. I have connected a 6 gauge stranded cable from this switch to the shack ground rod.

I have ordered and will receive a entrance ground panel http://www.kf7p.com/KF7P/EntrancePanels.html with Alphadelta bulkhead surge protectors, which will be connected to the shack ground rod by 4 gauge solid.

Also, I have both my coaxes and 6 gauge stranded running thru the basement window and right to the concrete floor, and is not going over and piping or electrical wire.

I guess my only question would be if the 6 gauge stranded is good enough for the switch to the ground rod.
« Last Edit: June 08, 2012, 04:45:57 PM by N4NYY » Logged
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