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Author Topic: Lightning Grounding for new shack  (Read 2774 times)
KC3EYS
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« on: August 27, 2018, 07:59:15 AM »

Hi everyone!

I just moved into a new home recently, and am excited to finally have some real estate to finally set up a nice shack in my finished basement and would like some insight.  Here's the setup:

Half of the basement is finished basement which I intend on putting my desk and an 1-2 HF rigs and a mobile VHF rig in.  Has all new GFCI outlets and the whole nine yards as far as electrical safety goes.  The desk will most likely be on the back wall (west) of the basement, facing the rear portion of my property (where the antennas will most likely live).  There is a small window in the unfinished side leading out the back (still on the west wall), which is where the dryer vent is routed to the outside.   Perfect spot for my feed lines to route outside also, as it is only about five feet from where my desk would be in the finished side...Here's where it gets fun....

The electric was recently updated prior to buying the home.  Originally, the main electric ground was routed to the cold water pipe on the front of the house (east wall),  which is directly opposite to the window I referred to above.  With the updates to wiring, the electrician also run two more ground copper braids, one which connects to my garage subpanel (south wall) and one which I discovered to be running out the window on the west wall.  So I have two new grounds run across the entire unfinished part of the basement.

I intend on putting some grounding roads for lightning/RF in the back yard (west) and hopefully tying that to the service ground to keep it all at the same potential during an event.  My concern is this:

Do I just simply tie my grounding rods in the yard to the west ground rod outside the window?  Or do I need to route it all the way around the house to the cold water pipe on the east side, and remove the interior connection to prevent a nice entry point for a lightning strike to travel the length of my basement....or am I just overthinking this?

I appreciate any thoughts or ideas on what would be the best (safest) avenue before I get too drill-happy getting set up Smiley
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AA4PB
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« Reply #1 on: August 27, 2018, 08:58:30 AM »

For lightning protection, the coax shields should be grounded to ground rod(s) on the outside of the house, fairly close to the entry point. The NEC requires that all grounding systems in the house be bonded together via at least #6 wire. This is for personnel safety to ensure that all ground systems are at the same potential. The grounding systems can be tied together at any point, including the rods themselves.
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Bob  AA4PB
Garrisonville, VA
KC3EYS
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« Reply #2 on: August 27, 2018, 10:16:32 AM »

Yep...I think I got that part in the bag...as the ground rod on the west side of the house is only 3 feet from the entry point.   That window access would be a perfect spot for the SPGP I will be installing (with lightning arrestors too).  Got the arrestors on order and I can definitely run my inside cables to the SPGP with no problem.

My chief concern was whether that ground line inside the basement heading to the east side of the house where the service panel/entry is would be cause for concern, since both points are connected via the new copper braid running through the basement.  I would think that would be an open invitation for lightning to come in and check out my basement.

The Grounding and Bonding for the Radio Amateur book from ARRL emphasizes running all the outside lightning protection grounds to the electric service ground on the outside perimeter to give the lightning more chance to dissipate into the ground there instead of giving it a path to the inside of the home.  That's where I'm skittish of that new ground line installed.  NEC also recommends bonding both sets of grounds together as well, but they didn't seem to call out whether running the connection from lightning grounds to electrical service ground should be done INSIDE the house.

Now...I admit at this point don't know for a fact whether the original service panel ground connected to the water pipe was a true metal to earth (might be plastic outside??), and the electrician noted this and fixed it by installing a ground rod on the other side of the house, and I guess at this point it wouldn't matter...
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AA4PB
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« Reply #3 on: August 27, 2018, 10:44:56 AM »

I don't doubt that it is best to run the bonding wire underground around the house to the electrical service ground. However, consider that there are ground wires running all around the house to all the outlets and light fixtures that are connected back to the electrical service ground at the panel box anyway.

What was the electricians reason for running a second ground wire through the house to a ground rod on the other side when he already had a ground rod close to the panel box?

You might consider using three rods, separated by 8-feet and bonded together to ensure a better ground contact for the antenna ground.
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Bob  AA4PB
Garrisonville, VA
KC3EYS
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« Reply #4 on: August 27, 2018, 12:01:35 PM »

I don't doubt that it is best to run the bonding wire underground around the house to the electrical service ground. However, consider that there are ground wires running all around the house to all the outlets and light fixtures that are connected back to the electrical service ground at the panel box anyway.

What was the electricians reason for running a second ground wire through the house to a ground rod on the other side when he already had a ground rod close to the panel box?

You might consider using three rods, separated by 8-feet and bonded together to ensure a better ground contact for the antenna ground.

Good point Bob regarding all the rest of the wiring.  I do have the service panel sticker from the electrician, so I'm going to give him a call.  My first thought was he didn't trust the cold water pipe for a good ground and instead ran a "better" one where he could drive a rod down for ground.  I did notice he did run the ground line along (not bonded, but physically wrapped on the exterior conduit service pipe coming into the box before tying it to the cold water pipe....so even better?

If the new ground is sufficient...then all the better for me to tie into the SPGP and my ground rods I intend on driving in the yard outside, as it is all accessible.

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KD0REQ
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« Reply #5 on: August 27, 2018, 06:37:01 PM »

Code says two ground points on opposite sides of the house. I would rather have seen solud copper on the new runs isstead of braid, which wicks water and corrodes an insulating green. But local code variations vary. Your guy followed local code. If it bugs you, get a good handful of axle grease and saturate the braid. Otherwis , inspect it whenever your spidey sense tingles. Have fun on the bands!
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KB2WIG
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« Reply #6 on: August 27, 2018, 08:17:42 PM »



" Code says two ground points on opposite sides of the house. "



I've been out of the field for ? 30 years and my copy of da code is at least 25 years old. Where in the NEC is this requirement?

klc
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AA4PB
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« Reply #7 on: August 28, 2018, 08:07:42 AM »

Some areas now require more than one ground rod, but never heard of a requirement for them to be on opposite sides of the house.
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Bob  AA4PB
Garrisonville, VA
KD0REQ
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« Reply #8 on: August 28, 2018, 07:04:20 PM »

Too much happening to ight to get my copy of code. We have a home inspector blogging in this area (structuretech) and he posted it a few months ago. A code instructur, Mike Ross I think, has a tutorial up saying and showing the opposite sides thing is the new standard. IIRC this is partially due to plumbing rework now going to pex plastic, thus boom, you lose the water pipe ground. A lit of new feedline going in is now plastic as well. Cheap, fast, good, pick any two.
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KD9IQO
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« Reply #9 on: September 03, 2018, 09:06:03 AM »

Just something you might wish to consider:

https://www.alphadeltaradio.com/pdf/TT3G50F-2.pdf


de...........KD9IQO
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KB4VVE
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« Reply #10 on: October 15, 2018, 07:10:22 AM »

I don't doubt that it is best to run the bonding wire underground around the house to the electrical service ground. However, consider that there are ground wires running all around the house to all the outlets and light fixtures that are connected back to the electrical service ground at the panel box anyway.

What was the electricians reason for running a second ground wire through the house to a ground rod on the other side when he already had a ground rod close to the panel box?

You might consider using three rods, separated by 8-feet and bonded together to ensure a better ground contact for the antenna ground.

He's on the money, here.  One ground point for your station, but it's necessary to have all the various ground connected together and bonded to the station SPG.  Treat station ground wires as though they are conducting RF - because that is what a lightning strike is.
73, Greg
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VK2LEE
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« Reply #11 on: October 18, 2018, 01:57:58 AM »

Hi,
A few years ago, I had an earth stake located in the floor of My shack and My Yagis located on a tower were hit with lightning, which wrecked all My New RG213 cables and burnt out the rotator.. Luckily I had nothing connected to the coaxial cables inside, as the lightning came inside down to the lightning rod... So, that wasn't a great idea.  It also melted a couple of N connectors too....
I have read where it is recommended to connect Your shack ground/earth, to the house ground/earth...  but everyone I asked in Australia said that was a VERY BAD idea...
 It was best to keep Your SHACK ground/earth separate....  It is usually recommended to have 3 ground rods about 3 meters apart and all tied together with heavy copper wire or braid...   I have just had My electrical meter box renewed using Earth leakage circuit breakers. The original Ground is a water pipe driven into the ground below the meter box and it wasn't replaced...   You need to remember that having antennas in the air will bring Lightning or even static electricity into Your Basement.... I use lightning arrestors in all My coaxial cables before they enter the house, but if there is lightning about locally, I climb a step ladder and unscrew all the cables, just to be safe.... the adaptors are connected to two earth/ground stakes about 3 meters apart... So, all My coaxial cables are grounded in the shield...     I also have My tower connected to a heavy cable [car battery cable] and connected to another earth/ground stake...  I used to have a full wave loop on 80 meters, which was an excellent antenna, but when Lightning was about You could hear the arcing inside the lightning arrestors.... from the static electricity.... It would give you a good shock too.... I hope that helps..
PS: The ground/earth rod in the floor of the shack is still there but connected to nothing.... Hi Hi...   Lee   VK2LEE
 
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28 years as VK2LEE - The 1st 3 letter L call ever issued - in 1986 -
VK6HP
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« Reply #12 on: October 18, 2018, 03:40:51 AM »

Lee

You need to stop and think about what you're trying to achieve.  Ideally, you'd bond everything to an infinitely large, perfectly conducting (hence equipotential) surface.  That's not possible in practice of course and the best you can hope to achieve, in the face of risk from lightning (etc) introduced by the MEN distribution system, your antennas, or other source, is a local earth zone supporting little potential difference. With AS3000 dictating the requirements for consumer premises and related earthing, meaning that all your radios and other equipment (including towers) are connected to mains earth, you should be looking to ensure that your external lightning ground path presents a lower impedance than the path back through the mains earth. If that lower impedance isn't present, it doesn't matter how heavy your cables from the tower to your lightning earth point are - the surge current will still flow preferentially through the mains earth. If the lower impedance is in place, the current flows via the lightning earth path, and the connection to the mains earth is not a problem. Depending on where you live, and the soil involved, 3 rods with no mesh could be inadequate. Some Australian soils are very poor conductors by the international standards often used in exemplar papers.

If you're in the happy situation of building a new shack inside or outside your house, there are are various optimizations possible, including provision of separate power circuits and placement of antenna cable entry boxes and their bonding systems.  But the basic physics (not to mention AS3000) still apply.

Just to give you an idea of what is done by a large Authority in your part of the country, you might find this NSW Rail Corp document interesting: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&uact=8&ved=2ahUKEwjWy-T44Y_eAhXEvY8KHUw-Dww4ChAWMAN6BAgIEAI&url=https%3A%2F%2Fwww.transport.nsw.gov.au%2Fsystem%2Ffiles%2Fmedia%2Fasa_standards%2F2017%2Fesm-109.pdf&usg=AOvVaw1jb4oXNPr05uc3QlHZEiAC.  Note especially Figure 2 and surrounding explanations. (Apologies for the long link; for some reason I couldn't get to a workable short-form one).

The other thing I'd question is the safety of climbing ladders to disconnect cables with a thunderstorm looming!  Best to get your arrestor and surge diversion system in place, and terminate or ground your antennas at a safe point.  

73, Peter.

 
« Last Edit: October 18, 2018, 03:48:58 AM by VK6HP » Logged
VK2LEE
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« Reply #13 on: October 18, 2018, 05:00:46 PM »

Peter VK6HP
Very interesting Earthing information there.... I do have copper water pipes under My house which I can access, plus the House Earth ground stake... so, I just need to connect them all together... then connect them to My earth rods etc and antennas.... which is a little bit harder....  I could move My Radio Shack 

Now 25 years ago, I just ran all My coaxial cables under the eaves across the ceiling and down inside a wall to My Radios... All the antenna cables  terminated before they went into the roof with PL-259 connectors.  So all My shack cables are also terminated coming out from the eaves... So, it is here that I disconnect all the cables going into My Shack when Lightning is about...  Climbing a long Aluminium step ladder to access all those cables...  Not a really good idea, but the 25 year old system is still there.. Hi Hi....  The shields are always earthed , but I hadn't thought of grounding all the antenna cables inner & outer..?? so all the antennas are grounded too... So, more to do there....  a lot more thinking... and doing.... Hi Hi....
Lee   VK2LEE
...
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28 years as VK2LEE - The 1st 3 letter L call ever issued - in 1986 -
W4KVW
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« Reply #14 on: November 03, 2018, 10:30:41 AM »

I always wondered why if Lightning is looking for a good ground why do we try & provide one? Seems as if that makes us a Big Target so I have never installed one since 1965 with ZERO issues.I'll stick with that record & let it find all of those Awesome grounds others have provided for it.  Grin Wink

Clayton
W4KVW
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