Grounding

[jazzboypro]

Hello,

I've been reading a bit about grounding antennas and equipment. Not sure i understand all of it. In a few weeks (when it finally gets warmer) i will be installing a brand new Comet GP-3 antenna (2 meter/70 Cm). I will probably be using a piece of 2 inches PVC pipe as a mast and the mast will be attached to the upper part of a brick chimney. The chimney is directly attached to my house. The feedline will be 75 feet of LMR400. I have a couple of questions.

1- Since the mast is non conductive i assume there is no reason to ground it ?
2- It is my understanding that the coax (braid) should be grounded at the point where it enters the house and an 8-10 feet ground rod should be used. Because of the type of soil i have (lots of rocks) i don't think it will be possible to use such a long ground rod what is the impact of using shorter rods ?

3- I have read that the ground rod used for the coax (and the one used for the mast if any)should be bound to the main electric service ground. I have no clue where that ground is, what happens if the ground rod is not bound to the main electric service ground ?

4- As far as the radios are concerned, the ground posts of my 2 radios are attached together to the cold water pipe. Is this sufficient ?

Thanks
73
VA2FCS

 

[mmckenna]

Hello,

I've been reading a bit about grounding antennas and equipment. Not sure i understand all of it. In a few weeks (when it finally gets warmer) i will be installing a brand new Comet GP-3 antenna (2 meter/70 Cm). I will probably be using a piece of 2 inches PVC pipe as a mast and the mast will be attached to the upper part of a brick chimney. The chimney is directly attached to my house. The feedline will be 75 feet of LMR400. I have a couple of questions.

1- Since the mast is non conductive i assume there is no reason to ground it ?

PVC would be a poor choice for antenna mast. It'll flex to much and will eventually fail. You really need to use something more rigid.
However, even with a non-conductive mast, the risk for lightning finding your antenna and using the coaxial cable as a path into your home is still there. You would, at minimum, want to ground the antenna base as well as the coaxial shield. In the USA, the National Electric Code requires this. Not sure what the Canadian rules say, but I suspect they are similar.

2- It is my understanding that the coax (braid) should be grounded at the point where it enters the house and an 8-10 feet ground rod should be used. Because of the type of soil i have (lots of rocks) i don't think it will be possible to use such a long ground rod what is the impact of using shorter rods ?

You can use several shorter rods, you can run ground rods in at an angle, you can dig a hole and bury a rod, lots of options. Usually at commercial sites, there are lots of methods used on rocky mountain tops. Usually the aim is to get a 5Ω or less path to ground.
Keep in mind that the local electrical code will probably require the new ground rod and the homes existing ground rod (usually at the electrical/hydro service entrance) be bonded together. This is a good place to consult with a local electrician that fully comprehends the local codes.

3- I have read that the ground rod used for the coax (and the one used for the mast if any)should be bound to the main electric service ground. I have no clue where that ground is, what happens if the ground rod is not bound to the main electric service ground ?

You'll need to find it. Your home should have one, and did at one time, if it met code. That may be a ground rod in the ground, rebar in the foundation, etc. Again, a good time to have an electrician come in and take a look. If your home doesn't have a ground rod, you have serious issues brewing and you want to get that resolved. It's a safety/fire issue that needs to be addressed.

4- As far as the radios are concerned, the ground posts of my 2 radios are attached together to the cold water pipe. Is this sufficient ?

That may or may not be a good ground. If the water piping in your home is copper/metal pipe all the way through the system to the point it connects to your water utility, then it should be grounded. If you cannot find your homes electrical ground, then I'd suspect everything and anything electrical related in your home as being in need of attention. Not trying to freak you out, but grounding is important. You really want to do it right. Floating grounds, especially with antennas involved, is a big risk.
If any of the piping is PVC, PEX, etc, then it's non conductive and you don't have a ground connection.
Ideally, you want your station equipment bonded to the same ground system as the antenna. I'd get a ground buss and mount it near your radios, then run a large ground conductor to the ground rod.

Thanks
73
VA2FCS

You are welcome, but please don't take my words as gospel. I'm in another country and rules here may be different. You really should consult with a local electrician to make sure this is all done correctly. Getting it wrong can mean fire, injury, damage to your home, damage to the electronics in your home, etc. That damage can be expensive and cost way more than hiring a competent electrician.

Also, you'll probably get someone who's going to complain about mounting antennas to the chimney. With small antennas and the right type of mount, it's not an issue.
Some will tell you that chimneys are not reinforced and not suitable for supporting anything. Not always true. Down here in California earthquake country, chimneys are reinforced with rebar. It's very common to see tall/large TV antennas mounted to them.
Again, for a small antenna, its probably not going to be a big deal. For larger antennas/masts, it can be. It's a good idea to find out what you have and design your antenna system accordingly.

 

[prcguy]

I've seen some houses way north of Quebec, Saint-Jerome I think with unusual power feeds like no neutral, just a single hot wire from the pole and everyone in the neighborhood had a ground rod. The opposite can be found with a hot and neutral but no ground rod.

You'll need to find it. Your home should have one, and did at one time, if it met code. That may be a ground rod in the ground, rebar in the foundation, etc. Again, a good time to have an electrician come in and take a look. If your home doesn't have a ground rod, you have serious issues brewing and you want to get that resolved. It's a safety/fire issue that needs to be addressed.

 

[littona]

#1 - correct
#2 - Get your hands on a polyphaser. Great lightning protection and grounding - just wire it inline and run your ground wire to it. https://www.polyphaser.com/search?C...pssp99app=Amateur+Radio&sort=y&view_type=grid
#3 - Don't mess with your electric service ground. They typically connect to a single ground rod near the meter. If you disconnect it, bad things may happen to yourself and your house. You'd be best served running your own ground. You can connect several short ground rods together which is equivalent to one long rod.
#4 - Depends on how old your house is... so many houses are using PEX. If it's all copper from where you connect and into the ground, then yes.

 

[mmckenna]

I've seen some houses way north of Quebec with unusual power feeds like no neutral, just a single hot wire from the pole and everyone in the neighborhood had a ground rod. The opposite can be found with a hot and neutral but no ground rod.

Single Wire, Earth Return. Used in some really rural areas. Works well as long as the ground is good. I think the standard is to run in two ground rods at least. One at the terminating pole, one at the next pole up the line just in case the other fails.

Single-wire earth return - Wikipedia

en.wikipedia.org

 

[jazzboypro]

PVC would be a poor choice for antenna mast. It'll flex to much and will eventually fail. You really need to use something more rigid.
However, even with a non-conductive mast, the risk for lightning finding your antenna and using the coaxial cable as a path into your home is still there. You would, at minimum, want to ground the antenna base as well as the coaxial shield. In the USA, the National Electric Code requires this. Not sure what the Canadian rules say, but I suspect they are similar.

I can find something more rigid no problem with that, since the mast would be quite short i thought i would be ok with PVC. We don't have very strong winds over here and no hurricanes/tornados/tropical storms. But using something stronger is probably the way to go just to be on the safe side.

You'll need to find it. Your home should have one, and did at one time, if it met code. That may be a ground rod in the ground, rebar in the foundation, etc. Again, a good time to have an electrician come in and take a look. If your home doesn't have a ground rod, you have serious issues brewing and you want to get that resolved. It's a safety/fire issue that needs to be addressed.

I just took a look at my electric service panel (the panel is in the basement. There is bare coper wire running out of it. The wire run down the wall, i will have to remove a piece of plywood to see where that wires goes. If it goes to the ground rod it it means that the rod is at least 5 feet under the ground and no way to access it from the outside.

That may or may not be a good ground. If the water piping in your home is copper/metal pipe all the way through the system to the point it connects to your water utility, then it should be grounded. If you cannot find your homes electrical ground, then I'd suspect everything and anything electrical related in your home as being in need of attention. Not trying to freak you out, but grounding is important. You really want to do it right. Floating grounds, especially with antennas involved, is a big risk.
If any of the piping is PVC, PEX, etc, then it's non conductive and you don't have a ground connection.
Ideally, you want your station equipment bonded to the same ground system as the antenna. I'd get a ground buss and mount it near your radios, then run a large ground conductor to the ground rod.

I was able to check continuity between the plumbing and the ground wire beside the utility panel and i can say that the plumbing and the ground wire are connected together

I've seen some houses way north of Quebec, Saint-Jerome I think with unusual power feeds like no neutral, just a single hot wire from the pole and everyone in the neighborhood had a ground rod. The opposite can be found with a hot and neutral but no ground rod.

I'm about 24 miles south of St-Jérome, i don't think we have that kind of system.

 

[rja1]

You really DO need to tie the shack ground to the service entrance ground. Remember, the earth acts like a big resistor. If you have a close in lightning strike, there could be 10's of kilo volts difference of potential between those ground rods if they are not tied together. In a perfect world, you want everything to rise (in potential) and fall AT THE SAME TIME.
Years ago, I had just finished my single point ground system in the shack and individual runs from the garage, shed and shack to the service entrance ground rod. About 3 weeks later, we had a really nasty t-storm & had a cloud to ground strike very close to the house. I was lucky, I only lost the cable modem, tv box & 2 computers (Comcast replaced the modem & tv box and the insurance company bought us 2 new computers). In the days following the strike, I saw 2 neighbors replace flat screen TV's and another one had to have a well pump replaced.
In the shack, the Flex 5000, Alpha 86 and a bunch of scanners all survived. I replaced the corroded piece of junk arrestor on the RG-6 cable with a Polyphaser 75 ohm arrestor & never had another problem.

P.S. The insurance company let me keep the old computers.......turns out all they needed was a pair of Wi-Fi cards & both were salvaged

 

[jazzboypro]

You really DO need to tie the shack ground to the service entrance ground. Remember, the earth acts like a big resistor. If you have a close in lightning strike, there could be 10's of kilo volts difference of potential between those ground rods if they are not tied together. In a perfect world, you want everything to rise (in potential) and fall AT THE SAME TIME.
Years ago, I had just finished my single point ground system in the shack and individual runs from the garage, shed and shack to the service entrance ground rod. About 3 weeks later, we had a really nasty t-storm & had a cloud to ground strike very close to the house. I was lucky, I only lost the cable modem, tv box & 2 computers (Comcast replaced the modem & tv box and the insurance company bought us 2 new computers). In the days following the strike, I saw 2 neighbors replace flat screen TV's and another one had to have a well pump replaced.
In the shack, the Flex 5000, Alpha 86 and a bunch of scanners all survived. I replaced the corroded piece of junk arrestor on the RG-6 cable with a Polyphaser 75 ohm arrestor & never had another problem.

P.S. The insurance company let me keep the old computers.......turns out all they needed was a pair of Wi-Fi cards & both were salvaged

I did some checking and i can say that the ground post on both radios are connected via the cold water pipe to what appears to be the ground wire of the service panel. I still need to find where the other end of the wire goes but since the panel is in the basement and that the wire is going down the wall it as to go outside well below ground level to the ground rod.

If i have to bound my own ground rod to the service panel ground it will have to be via a wire that will run inside my house.

 

[dlwtrunked]

PVC would be a poor choice for antenna mast. It'll flex to much and will eventually fail. .
...

Unless PVC is UV (ultraviolet) resistant if will fail (become extremely brittle) quicker in even partial sunlight than most people think. Furniture grade UV resistant PVC makes a nice antenna enclosure but as you say, for physical strength and grounding purposes, a metal mast must be used.

 

[mmckenna]

I can find something more rigid no problem with that, since the mast would be quite short i thought i would be ok with PVC. We don't have very strong winds over here and no hurricanes/tornados/tropical storms. But using something stronger is probably the way to go just to be on the safe side.

Ideally, yes, that's a good idea. As dlwtrunked said above, some types of PVC will break down when exposed to UV light (sunlight) and get brittle.
The PVC won't keep you from having to do all the grounding measures, so it really is a good idea to just go with a piece of rigid conduit. Usually 1" or 1 1/4" is suitable for hobby type antennas, and you can pick it up at most large hardware stores.

I was able to check continuity between the plumbing and the ground wire beside the utility panel and i can say that the plumbing and the ground wire are connected together

That's good, but you really don't want to use that as your ground. Remember, lightning has no issues at all making it thousands of feet throug the air (air is a very good insulator). You really, really, seriously want to get all that energy to ground as quickly as possible. You don't want any of it traveling through your plumbing system, and thus all around your house. Getting a lightning strike while someone is using the shower won't be an enjoyable experience.

It's common, and I think code, for cold water pipes (if they are metal) to be bonded to ground.

For your shack ground, put a ground buss somewhere near your radios. Connect that via heavy gauge copper wire to the ground rod.

And remember, it's not just direct lightning strikes you need to worry about. Even a nearby lightning strike and induce a lot of energy into any nearby metallic items, like antennas.

 

[jazzboypro]

Ideally, yes, that's a good idea. As dlwtrunked said above, some types of PVC will break down when exposed to UV light (sunlight) and get brittle.
The PVC won't keep you from having to do all the grounding measures, so it really is a good idea to just go with a piece of rigid conduit. Usually 1" or 1 1/4" is suitable for hobby type antennas, and you can pick it up at most large hardware stores.




That's good, but you really don't want to use that as your ground. Remember, lightning has no issues at all making it thousands of feet throug the air (air is a very good insulator). You really, really, seriously want to get all that energy to ground as quickly as possible. You don't want any of it traveling through your plumbing system, and thus all around your house. Getting a lightning strike while someone is using the shower won't be an enjoyable experience.

It's common, and I think code, for cold water pipes (if they are metal) to be bonded to ground.

For your shack ground, put a ground buss somewhere near your radios. Connect that via heavy gauge copper wire to the ground rod.

And remember, it's not just direct lightning strikes you need to worry about. Even a nearby lightning strike and induce a lot of energy into any nearby metallic items, like antennas.

I get that but at some point there is what should be done and what can be done. My operating position is simply not near the service ground rod
and i'm pretty sure the rod itself is not accessible from within the house. Yes i could prevent from connecting my radios to the plumbing system by running a wire from a buss near the radios to the ground wire that goes to the rod but that wire would be about 30 feet long at best. The same goes from the ground rod use for the coax. The way i see it unless the house as been designed and built to accommodate the proper installation of a radio room and antennas, it's nearly impossible to achieve a state of the art ground system.

 

[mmckenna]

I get that but at some point there is what should be done and what can be done. My operating position is simply not near the service ground rod
and i'm pretty sure the rod itself is not accessible from within the house. Yes i could prevent from connecting my radios to the plumbing system by running a wire from a buss near the radios to the ground wire that goes to the rod but that wire would be about 30 feet long at best. The same goes from the ground rod use for the coax. The way i see it unless the house as been designed and built to accommodate the proper installation of a radio room and antennas, it's nearly impossible to achieve a state of the art ground system.

It's your choice.

Here in the USA, the National Electric Code exists for a reason. It's based off fire code, and what has been learned over decades of researching what starts fires in the home.

If you are going to go this route, make sure you disconnect your antennas and toss the cable outside when you are not actively using them and when you are not at home.

Chances are your home will never get struck by lightning. Probably.

 

[CanesFan95]

My electric meter has a little panel with 6 screws to attach ground wires. The panel is hooked into the ground rod through a connection built in to the wall of the house. The ground rod itself is a little below the surface of the ground with a short piece of white PVC pipe around the top of the rod. It would be difficult to connect directly to the ground rod itself.

See if you have a similar type panel you could hook into with the ground wire. When I had cable service installed, they attached a grey box to the outside wall next to the electric meter. Then they hooked a short ground wire from the box to one of the six screws. Then for my antennas, I hooked my ground wire to another screw. Now I've only got 4 screws left !

 

[CanesFan95]

There's someone name KF5LJW over on the QRZ forums who insists on not installing more ground rods and only using the one original ground rod at the house, thus the phrase "single-point grounding system". And you want the ground wire to be the shortest distance straight down with no sharp turns. I think it was something like adding more ground rods could cause a potential difference that could fry everything between the 2 rods?

So isn't it ironic how most antennas say don't install near power lines? Because where the power lines come in to the house is usually right exactly where the dang ground rod is !

 

[jazzboypro]

It's your choice.

Here in the USA, the National Electric Code exists for a reason. It's based off fire code, and what has been learned over decades of researching what starts fires in the home.

If you are going to go this route, make sure you disconnect your antennas and toss the cable outside when you are not actively using them and when you are not at home.

Chances are your home will never get struck by lightning. Probably.

Don't get me wrong I don't doubt what the NEC says, i understand that it is how it should be done. I looked a bit at our code here in Canada and it is pretty much like yours's. I wander how many amateur radio operators can actually do it that way. I am not choosing to do it in a certain way, i just work with what i have. The antenna mast and the utility ground rod are at opposite sides of the house some 45 feet apart. Bringing the antenna closer to the rod would put the antenna very close to the power line entering my house. The coax will enter my house just about in the middle of the house so the ground rod for the coax would some 24 feet away form the utility ground rod. Unfortunately, tossing the cable outside will not be possible either.

 

[CanesFan95]

^ What you just described right there is a common issue and basically makes grounding in this hobby pain in the ass.

 

[prcguy]

If your water pipe is close to where the coax will enter the house and the water pipe is also close to the point where it enters the ground, then grounding to the water pipe should meet code. You would need at least 10ga copper wire to a lightning arrestor in the coax line with the least amount of ground wire and the least amount of bends in the wire possible.

You must realize you will not survive a direct lightning hit and this is more to meet electrical code for human safety and to possibly survive distant lightning strikes.

 

[jazzboypro]

So isn't it ironic how most antennas say don't install near power lines? Because where the power lines come in to the house is usually right exactly where the dang ground rod is !

I also came to that conclusion. Also in my case keeping the ground wire short and straight is not possible

My electric meter has a little panel with 6 screws to attach ground wires. The panel is hooked into the ground rod through a connection built in to the wall of the house. The ground rod itself is a little below the surface of the ground with a short piece of white PVC pipe around the top of the rod. It would be difficult to connect directly to the ground rod itself.

See if you have a similar type panel you could hook into with the ground wire. When I had cable service installed, they attached a grey box to the outside wall next to the electric meter. Then they hooked a short ground wire from the box to one of the six screws. Then for my antennas, I hooked my ground wire to another screw. Now I've only got 4 screws left !

I will check that out tomorrow but the wire going to that box would remain pretty long

 

[CanesFan95]

Believe me, I'm in the same boat. Radio room? 2nd floor, back of the house. Where's the ground rod? Frickin' front of the house.

 

[jazzboypro]

If your water pipe is close to where the coax will enter the house and the water pipe is also close to the point where it enters the ground, then grounding to the water pipe should meet code. You would need at least 10ga copper wire to a lightning arrestor in the coax line with the least amount of ground wire and the least amount of bends in the wire possible.

You must realize you will not survive a direct lightning hit and this is more to meet electrical code for human safety and to possibly survive distant lightning strikes.

The pipe is very close to where the coax will enter house but unfortunately some 25 feet from where the pipe enters the ground. Yes i get that i would not survive a direct hit. Like I've said achieving ideal ground system is next to impossible unless the house has been design and built with that in mind. The question is is a less than ideal ground better than no ground at all or would it be more dangerous than no ground at all.

I really appreciate every ones input on that subject it is a very interesting subject.