In UK the "house" ground is usually connected "earth" and connected to neutral at the substation (transformer for the locality). In Ireland there is supposed to be a 1.5m approx galvanised earth spike near the meter box or grid input and the neutral and earth are bonded there. That's quieter.

Maybe 50 years ago people might have used the water pipe as an RF earth, but that might be plastic. You're not supposed to use any utility pipes, central heating pipes etc as a radio Earth.

Don't connect your own Earth spike to the mains supply Earth. They need isolated, especially on the UK system as large currents might flow. The exception might be if your neutral and earth are bonded at the meter box and go to a nearby earth spike and there is no utility company earth.

Every non-loop aerial has a "counterpoise" even if you can't see it. A vertical needs either to be driven at earth level, or have 1/4 wave or more radials or counterpoise, or a sleeve that is earthed only at drive point with an internal diameter ratio with coax outer diameter to give the 50 or 75 Ohms. An unfolded, non-loop, dipole obviously has a "counterpoise".

The end fed Zepp (so called because used on the Zeppelins as a radio aerial) doesn't seem to have a counterpoise, but has really, on the modern version the feed line is the counterpoise. https://owenduffy.net/blog/?p=7165 Similarly the over hyped G5RV is only a proper dipole at one narrow band, otherwise the feed cable is the aerial (and partly counterpoise) and then the counterpoise is really the shack earth.

The thing to avoid is an exactly half-wave radiator or counterpoise as that has a very high impedance.

How do you prevent damage from a lightning event if everything is not referenced to one ground (earthing point)?
The potential difference between the two, or more, earth points can be very substantial.
This potential difference is what causes the damage.

Glenn

In UK the "house" ground is usually connected "earth" and connected to neutral at the substation (transformer for the locality). In Ireland there is supposed to be a 1.5m approx galvanised earth spike near the meter box or grid input and the neutral and earth are bonded there. That's quieter.

Maybe 50 years ago people might have used the water pipe as an RF earth, but that might be plastic. You're not supposed to use any utility pipes, central heating pipes etc as a radio Earth.

Don't connect your own Earth spike to the mains supply Earth. They need isolated, especially on the UK system as large currents might flow. The exception might be if your neutral and earth are bonded at the meter box and go to a nearby earth spike and there is no utility company earth.

Every non-loop aerial has a "counterpoise" even if you can't see it. A vertical needs either to be driven at earth level, or have 1/4 wave or more radials or counterpoise, or a sleeve that is earthed only at drive point with an internal diameter ratio with coax outer diameter to give the 50 or 75 Ohms. An unfolded, non-loop, dipole obviously has a "counterpoise".

The end fed Zepp (so called because used on the Zeppelins as a radio aerial) doesn't seem to have a counterpoise, but has really, on the modern version the feed line is the counterpoise. https://owenduffy.net/blog/?p=7165 Similarly the over hyped G5RV is only a proper dipole at one narrow band, otherwise the feed cable is the aerial (and partly counterpoise) and then the counterpoise is really the shack earth.

The thing to avoid is an exactly half-wave radiator or counterpoise as that has a very high impedance.

-- 
-----------------------------------------------------------------------
Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv@...    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA-LM    ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

On Sat, Nov 16, 2024 at 05:10 PM, Glenn Little wrote:

How do you prevent damage from a lightning event if everything is not referenced to one ground (earthing point)? The potential difference between the two, or more, earth points can be very substantial. This potential difference is what causes the damage.

Glenn

A single "ground" makes little or no difference. You need all aerials and power cables, Cable TV, phone cables disconnected. A strike even 100m from the utility cables (even buried electricity, phone, cable TV etc) can induce 1000s of volts and destroy front ends of TV, radio, DSL modem, cable modem, analogue dial up modem. Even blow the tops of the RS232 interface ICs on the motherboard (amazingly a plug-in RS232 card and new modem worked once they repaired the exchange, the Mobo survived).

There are reasons for a single electrical safety earth do to with ELCB / RLCB / RCCB tripping and safety. As mentioned, the UK mostly is a different scheme (3rd wire with earth to substation) to Ireland (an earth spike per meter box and no 3rd wire). Unlike USA, UK & Ireland homes are only single phase. The houses alternately use the three phases in built up areas, so don't share any electrical device connection with a neighbour without suitable isolation or barrier earth (shared TV aerials or sat dishes).

Radio earth connections want to be short to earth spike so there may be more than one.

Solar systems on a roof need the frames to a single earth to minimise static damage, useless on a direct or close strike. The battery negative should not be earthed except in certain circumstances. The neutral on an off grid PV inverter needs a single earth before the trip switch. Earthing (other than the isolated metal frames) of PV systems connected to a grid need an expert.

A Satellite dish or Aerial pole should go to a local earth spike to minimise static (dry wind) or damage from nearer but not direct hit lightning. The satellite dish electronics (ODU, LNB etc) should not be directly earthed.

It's complicated. But a single earth doesn't help with lightning. Disconnecting everything works best, but not fool proof if you get a direct hit.

See also EMP.

Here's what I have come to know about lightning.  The trick with lightning is less about ground and more about making sure that the lightning's energy is routed past (not through) you and your equipment.  Disconnecting the equipment is a common and effective method, so long as it can be done well before any strikes.  Being caught in the act of unscrewing that last connector when the strike occurs will get you a cameo appearance on a Saturday morning cartoon...  And, to be clear, a "strike" doesn't necessarily involve a direct hit.  Anything within miles can result in a significant local disruption.

The best approach involves two points.  First is to provide a path to Earth - where the lightning strike was going in the first place - that goes past your shack.  Lightning arrestors on all lines with a stout connection to a proper ground rod is a standard means to do this.  During a strike, the arrestor conducts the current coming down from the antenna to the ground rod, instead of letting it continue on the coax into the shack.

Second is perhaps the trickier part, and where that non-direct strike effect is dealt with.  A non-direct strike will raise the potential of the earth itself, but in an uneven way.  Closer to the strike will be higher than farther away.  The problem is that you need to make sure that all of your equipment - ALL of it - remains at a common voltage.  Note that this doesn't mean that it remains at a constant potential, but it doesn't have to.  Consider birds sitting on power lines; they don't care that they are at a kilovolt or two above ground because there's no current going through them.  Not so the squirrel with one paw on the line and another on the metal support pole.  So, make sure that everything has a common "ground" connection to each other, and to that same place the lightning arrestor is connected.  The lightning arrestor will rise in potential above ground during a strike, but if everything else rises exactly along with it, no current will flow. 

The complicating factor is when things are separated, which they usually are.  In my house, for example, the shack and its "ground window" are on one side of the house, and the electrical panel (where the equipment power is sourced) is on the opposite side.  I need to be sure that a strike doesn't raise the potential of the ground window and all of my equipment that's connected to it different from the electrical system they are plugged into.  If they did, then there would be a surge of energy through the equipment into its power cord and over to the electrical panel which has its own ground.  That means that I needed to run a wire to bond the ground stake on the ham side over to the electrical panel's ground to keep them at the same potential.  To this end we ran a fat wire (#6, I think) from one to the other.  But to this thread's comments, I did not mess with how the electrical panel manages its grounding with respect to the safety (green wire) and neutral (white) wires.  That's set by the local electrical code; here we connect them together, but that varies around the planet.  I only bonded the shack ground stake to panel ground, at the same place the panel's existing ground is attached.

Hope this helps,  (and that I got the details right!!).

Greg  KO6TH

I was chief engineer at a TV station in USA.
Everything was bonded to a single point ground.
Inside the building we used 6" flat copper strap.
We took many strikes to the 2000' tower, but never had an equipment damage.
With a single point ground, during a lightning strike, every thing elevates to the same level, at the same rate.
There is no damage as everything is referenced to the same point.
With a multi point ground there will be a difference in potential between equipment between the multiple points.
The is where damage occurs.
There will be a difference in potential between the grounds.
Reference MIL-HDBK-419, available on the web for more information.
Motorola generated their own site selection document (R-56), Our FAA (Federal Aviation Authority) as well as others generated their own standards documents, all based on MIL-HDBK-419.
Properly single point grounded sites suffer minimal damage because of the single point ground.
A multi point grounded system invites lightning damage.

Glenn

On Sat, Nov 16, 2024 at 05:10 PM, Glenn Little wrote:

How do you prevent damage from a lightning event if everything is not referenced to one ground (earthing point)? The potential difference between the two, or more, earth points can be very substantial. This potential difference is what causes the damage.

Glenn

A single "ground" makes little or no difference. You need all aerials and power cables, Cable TV, phone cables disconnected. A strike even 100m from the utility cables (even buried electricity, phone, cable TV etc) can induce 1000s of volts and destroy front ends of TV, radio, DSL modem, cable modem, analogue dial up modem. Even blow the tops of the RS232 interface ICs on the motherboard (amazingly a plug-in RS232 card and new modem worked once they repaired the exchange, the Mobo survived).

There are reasons for a single electrical safety earth do to with ELCB / RLCB / RCCB tripping and safety. As mentioned, the UK mostly is a different scheme (3rd wire with earth to substation) to Ireland (an earth spike per meter box and no 3rd wire). Unlike USA, UK & Ireland homes are only single phase. The houses alternately use the three phases in built up areas, so don't share any electrical device connection with a neighbour without suitable isolation or barrier earth (shared TV aerials or sat dishes).

Radio earth connections want to be short to earth spike so there may be more than one.

Solar systems on a roof need the frames to a single earth to minimise static damage, useless on a direct or close strike. The battery negative should not be earthed except in certain circumstances. The neutral on an off grid PV inverter needs a single earth before the trip switch. Earthing (other than the isolated metal frames) of PV systems connected to a grid need an expert.

A Satellite dish or Aerial pole should go to a local earth spike to minimise static (dry wind) or damage from nearer but not direct hit lightning. The satellite dish electronics (ODU, LNB etc) should not be directly earthed.

It's complicated. But a single earth doesn't help with lightning. Disconnecting everything works best, but not fool proof if you get a direct hit.

See also EMP.

-- 
-----------------------------------------------------------------------
Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv@...    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA-LM    ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Antenna ground or counterpoise isn't the same than house ground/earth neither serves the same purpose.

A counterpoise (grounded or not) is used to avoid returning RF towards the rig via balancing the antenna and is dependent of its design. What you're doing is using the house wiring in the hope that it'll become an RF sink but at same time you're adding all that wiring to the antenna. That may pick not only all the electrical noise of any posible derivation in the circuit but also letting it act as a -presumibly- huge antenna picking up whatever is around. It just happens that that also goes to the receiver.

Counterpoise length should be stated or suggested in the manual,

On Friday, November 15 2024, 14:32:21, John G0GCD via groups.io wrote:

Not FT817 directly, but I intend to use the kit with it.
The instructions say that best performance is had with a ground or a counterpoise. Just for fun, I tried the house ground and that's
extremely noisy. Any recommendations for a suitable length of counterpoise?

The intended use is on the dining table of any holiday let we stay in.. so it'll need to snake around the room, I think.

Also, any feedback on how well these antenna kits work? Anything is better than nothing but the vendor feedback has an equal
balance of (very) good and (very) bad reviews.

Thanks
John G0GCD

--
The less you know, the sounder you sleep.
--- Russian proverb

On Sun, Nov 17, 2024 at 12:00 AM, Glenn Little wrote:

Properly single point grounded sites suffer minimal damage because of the single point ground. A multi point grounded system invites lightning damage.

Assuming mast or skyscraper grade lightning conductor. Most of us don't have that, so one or several earths is moot.

On Sun, Nov 17, 2024 at 03:34 PM, Al WB9UVJ wrote:

Radials on the ground or in the ground cannot be made resonant due to the effects of the earth to detune those conductors.  The rule of thumb is to have as many radials on/in the ground as you can afford or have space for.  Ground conductivity affects/interacts with the radial system too.  Many operators start with 16 radials but often find that 32 or even 64 provide better efficiency.  As you increase the number of radials, you increase the Q of the antenna system by lowering the resistance (think resistors in parallel) in the resonant circuit of the antenna.

Yes, though if you are in a very wet location one earth spike might do.

Only radials that are in air, above the ground, can be resonant.