Ground Spike necessary ?

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Ground Spike necessary ?

Postby ur5by9 » Sun Mar 26, 2017 5:24 pm

Wonder if some one can tell me If a Ground Spike is necessary at the bottom of the mast?

I have a 3 section telescopic tennamast which is cemented into the ground using the ground socket in a cubic meter of structural strength cement.
A lot of conflicting information around the web regarding if a ground spike is required as technically the antenna mast is already in the ground down 1 meter.

What is your take on this and the requirements of fitting a ground system for the mast.

Information is with the greatest of thanks.
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Re: Ground Spike necessary ?

Postby m0lsx » Sun Mar 26, 2017 6:05 pm

The first thing I would say is, if you do use an earth stake, put it a small distance from the concrete base as I have seen a lightning strike crack a concrete base where the stake was beside the concrete.
So I would suggest from the above that an earth stake is a good idea, as imagine what would have happened if the easiest electrical route to earth had not been via the earth stake but via the mast it's self.
Next I would ask what is the earth stake for?
A lightning surge protector certainly needs an earth stake & a surge protector makes us feel better & even gives us an element of protection, but they are not good on all antennas & are not going to do much good protecting your radios in the event of a direct hit. But they do divert some surge to earth in the event of a hit & do protect us in part.
If I put any form of earthing wire, including lightning protection, onto my Diamond CP-6 the SWR goes to hell & that is true of many physically short verticals.
The next question would be, do you mean necessary or always advised or something else. As adding an earth stake is hardly going to be expensive or problematic.
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Re: Ground Spike necessary ?

Postby ur5by9 » Sun Mar 26, 2017 6:46 pm

That's a fair bit of useful information to go on, I'm in the process of setting back up my shack after being away from radio for a few years.
While I want to make sure I have a nice clean set up this was making me look at grounding the mast via a ground spike and also would I ground my radio station
via the same spike and how about the coax cable I see you can purchase a barrel coupler with an earthing terminal would this be necessary if the radio chassis is grounded?

The so239 or N type would be internally grounded to the radio, So if the Radio has a grounding system then would a coax earth be worth while?

Also what would I use as a spike? I have a length of copper pipe spare from a plumbing job I done in the house would I just drive this into the ground
or is there a better conductor to use as a ground?

Thanks for your information this does help me get it right.
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Re: Ground Spike necessary ?

Postby m0lsx » Sun Mar 26, 2017 7:41 pm

I forgot to mention the most important fact..
IF YOU HAVE PME DO NOT USE ANY EARTH STAKE UNLESS YOU KNOW WHAT YOU ARE DOING, OR HAVE TAKEN ADVICE FROM SOMEONE WHO DOES.
PME is where a group of building have a single earthing point & any additional earth could leave you at risk of electrocution if there is a fault anywhere in that system.


ur5by9 wrote: While I want to make sure I have a nice clean set up this was making me look at grounding the mast via a ground spike and also would I ground my radio station via the same spike


There is more than one type of earth in an amateur radio station, so use separate earth stakes for separate types of earth.
In general earth stakes should have the shortest possible wires to them, so take that into consideration too, as in certain applications, the longer the wire, the more chance it can became part of the antenna system, which is undesirable, as it can or almost certainly will, create it's own problems.
If you need an earth for a first, second floor shack then an artificial earth is worth considering. But do tape the end of any tunable counterpoise or artificial earth, as the voltages at the end of a tuned wire can be rather high & thus a fire risk.

Edited to add. Do not use your homes plumbing for an earth. Some people do, but that can again produce problems, due to the plumbing picking up & feeding unwanted electrical noise into your radio system. Plus if you do not have PME, guess where your mains electricity is earthed to?
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Re: Ground Spike necessary ?

Postby ur5by9 » Sun Mar 26, 2017 8:51 pm

I am unsure of which type of earth my house would have, Can i call my electricity supplier for this information?

I do have a standard looking DB board with rcd trip type fuses not the older wire type arrangement.
The board input is L N and E with standard earth tag inside the box, all twin and earth, earths all to the same bar.
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Re: Ground Spike necessary ?

Postby m0lsx » Sun Mar 26, 2017 10:46 pm

When was you home built or most recently rewired?
Most homes built since 1980 are PME & there should be a warning that the system is PME (a Sticker) on the meter or at the consumer unit to warn you.


The following is the RSGB leaflet. But be warned, it's PME & earthing is not a easy topic..

http://rsgb.org/main/files/2012/11/EMC07-final.pdf
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Re: Ground Spike necessary ?

Postby lars » Mon Mar 27, 2017 9:33 am

Not for the first time, I find the RSGB's guidance on electrical safety baffling. In this case, however, I suspect they are just reflecting the bafflement inherent in the IEE Wiring Regulations, which are written on the basis that construction practices have not changed since the 1950s. Concerning PME installations, I find it hard to believe that there is any kind of supply neutral fault that can make my RF earth the main carrier of neutral current _unless_ I follow the letter of the regulations, and bond it to the main earth terminal with a heavy conductor. That is, it is following the regulations that creates the need to follow the regulations :/

But the advice from the RSGB to convert your whole house to TT (local earth spike) strikes me as deeply misguided. For sure, it will make it easier to follow the letter of the law when it comes to RF grounds; but from a safety perspective a local earth spike will never be as good as good a safety earth as the supply company's terminal, even with PME.

It's notoriously difficult to construct an effective earth spike for safety purposes, and I suspect that is true for RF grounding as well. Unless you're very fortunate with soil type, a three-foot rod won't be an effective safety earth, and I doubt it will be an effective RF ground (although I confess that RF grounding is something of a mystery to me). It isn't unusual for a single earth spike to need to go down thirty feet. Lacking facilities to install a thirty-foot spike. what many people do is dig a pit or trench, install a number of linked spikes, and back-fill with a slurry made of crushed charcoal and salt. Getting good electrical contact between the spike and the soil touching it is not the problem -- the problem is that the soil itself is likely to be of low conductivity unless it is provided with additional conductive material.

I have a suspicion that people who find that an RF ground spike isn't doing what it ought to be doing, don't actually have an effective ground.
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Re: Ground Spike necessary ?

Postby milly » Mon Mar 27, 2017 11:10 am

As others have said there are many reasons why you might want to add an earth. Each will have it's own different needs.

For your own safety the tower should be earthed - but as Lars has said, a metre long earth spike is going to be pretty much useless (for any purpose, not just to protect the tower). If lightning hit your tower no damage might result...equally, I have seen a 3x3x3metre cube of concrete turned to high velocity rubble when a tower was hit. It removed the equipment cabin on it's tour of the hillside.

There is little point in attempting to earth things for safety unless you are going to do it properly - that means a lot of solid high surface area copper going very deep into slightly damp and conductive ground. Domestic 230v electrickery might be happy to follow a small stranded copper wire...lightning will just eat that for breakfast and look for something more filling.
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Re: Ground Spike necessary ?

Postby ur5by9 » Mon Mar 27, 2017 8:31 pm

My house is was build in 1990 and I see now warnings on my fuse board.

Taking on board that a bit metal in the ground is only as good an earth as the soil it is driven into.
I think I may just disconnect the antenna from the radio when not in use and keep the mast lowered at the same time.
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Re: Ground Spike necessary ?

Postby G4RMT » Mon Mar 27, 2017 9:20 pm

What exactly are you actually wanting to do?

All the very confusing regs are simply there for electrical safety - any benefits or problems with RF are secondary.

Are you thinking about lightning protection, or reductions in QRM, or something else?

Is the mast actually important? Loads of questions really - If the idea is simply you want to ground the mast, then that in itself is a tricky topic. Most people, I'm sure, don't - apart from the natural path through whatever base you have. There is some evidence that a metal structure that is effectively grounded becomes a lightning conductor - but the old adage that it always takes the most direct path to ground does appear to be true. Then we do the other thing of trying to make our antennas, especially verticals have a DC path, so that creates another path to the shack. Some people routinely disconnect their feeder cables to protect the radios in dodgy weather. Others like me are lazy and never do this.

Most people with towers start with the lowering routine, and give up. My own take on the issue is that if your time is up, then that's when your insurance does the worrying. I've spent the night on the top of a 200 ft grain silo, in a storm, with the repeater aerial over my head, and a lightning rod 10m away. Bloody scary watching the lightning conductor. At one point I could have sworn I saw it glow, but all my colleagues told me that was total rubbish - I don't know, but after that experience, being on the ground in a storm didn't worry me at all any more. If you have a well grounded lump of metal in the sky, that is pretty well making you a target, yet it's rare aerials get hit. No idea why lightning seems to target things you'd not expect, and ignores the obvious ones.

On the subject of the earthing arrangements, it's interesting to note that despite the neutral and earth being bonded together at the meter end, it's common to find a few volts difference by the time the cabling gets to your house's furthest point. If there is NOT a difference, as in a meter measures 0V it's considered an indication of a fault? In the electrics, the only thing the regs seek to do is make disconnect time short enough to protect life when circuit protection operates.

What exactly concerns you?
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