Driving a new ground spike

[Tubetec]

I had to recently drive a new domestic ground spike , the old one is still there ,connected and functional but the termination at the top was below ground which doesnt conform to the regs .
The top of the rod needs to be above ground , a metal clamp is used to terminate the wire , that is in turn housed in a plastic IP 67 sealed enclosure and the connection is wrapped in Denso or self amalgamaing water proof tape to help prevent moisture ingress . 10mm squared cable is the minimum requirement , I went with 16mm sq because I could .

Ive brought the cable up to the utility box , but of course thats as far as I can take the job , I have to wait now for the Electricity supply co to come ,remove the old ground and terminate the new cable into the junction box .

Of course Im well aware what Ive said above may or may not comply or be applicable with the local requirement where you are , main reason Im raising the subject here is the quality of ground connection plays an important role in supressing noise in audio equipment , but might also effect how fast the ELCB trips in the case of a fault current . The spec for the ground rod itself here is 16mm diameter galvanised steel ,1.2m lenght and it must be fully driven into the soil , shortning the lenght isnt allowed .
Anyway if your running audio gear and are experiencing noise issues it may well be worth having the earth rod/termination checked for integrity .
I presume when the Electric co call out they have a way of measuring the resistivity(?) through ground back to the local pole/transformer grounding plate .

 

[ccaudle]

the quality of ground connection plays an important role in supressing noise in audio equipment

It should not if the equipment is competently designed at all, and probably not even if the equipment is incompetently designed.
If all audio equipment within the building is connected together through cable shields and power cable green wire, in what way do you foresee the impedance of the entry point green wire to physical earth affecting the audio noise?

The purpose of safety wire connections to chassis is to provide a low impedance connection back to neutral in case of hot wire fault to chassis so that the circuit breaker will trip. The purpose of building safety wire to (physical) earth connections is to keep the neutral line voltage and any building plumbing or metal structrual elements at close to the same voltage and to limit power system voltage rise from nearby lightning events.

So you should definitely have a good quality connection between power entry and physical earth, but for electrical safety reasons, not related to noise in audio systems.

might also effect how fast the ELCB trips in the case of a fault current

If that is the case you have outdated ELCB devices (i.e. 60 year old design) and you should update to the 40 year old design which does not rely on an earth connection at all to function properly. I'm not sure what part of the world you are located, in North America they are called ground fault circuit interrupt (GFCI) and will operate even if there is no green wire connection, because it senses any current imbalance between the hot and neutral power lines, no matter whether that difference current travels through safety earth connection.
ELCB article
RCD/GFCI article

 

[PermO]

1,2 meter only ?

I've seen pins go in as deep as 11 meters here.

A couple years ago, working at an outdoor event a guy gave me a 30cm copper pipe "stick it in the grass" .. I was like "what's that ?" he told me it was the grounding rod for the stage.... I told him it was not

 

[JohnRoberts]

I thought the ground spike for domestic residential power distribution is a steering path for lightning discharges.

Ground networks for radio antennas are more involved.

JR

 

[abbey road d enfer]

1,2 meter only ?

I've seen pins go in as deep as 11 meters here.

I believe it depends on regulations. Length means nothing. It's the actual resistance that matters. Actual soil humidity matters as much as length. I read that in some areas it is impossible to achieve a low ground resistance, because of granitic soil, so cheating earth (using neutral as earth) is/was admitted.
But it matters only for safety, not for audio performance. Audio equipment works very well in a plane.

A couple years ago, working at an outdoor event a guy gave me a 30cm copper pipe "stick it in the grass" .. I was like "what's that ?" he told me it was the grounding rod for the stage.... I told him it was not

It would be a problem only if a singer walked from the stage to the ground with a long mic cable, or if the soil was extraordinarily dry.

 

[PermO]

Yes I've seen the guys taking measurements and adding rods till they hit the mark.
In this case it was a "clean ground" for a lab's instrumentation, there allready was a utillity ground on the mains but those were to be kept separate.

I wonder how they measure this, how do you reference a ground connection ? do they reference to the existing mains ground ?

In case of the stage, a big metal construction in an open field, sitting on wooden boards on the grass and the only ground connection is a 30cm copper pipe ?
I'm talking lightning protection here.
The regulations for a temporary safety ground on a stage are the same as the one for your house and I don't think a 30cm copper pipe is a sufficient ground connection in case of a lightning strike.



(Yes there is mains ground on all the electrical equipment)

 

[dmp]

I had to drive two 8 foot 5/8" dia ground rods. Connection to them was underground a few inches with bare copper wire (seems having them poking out of the ground would be unsafe?)
Inspector didn't make any measurements when signing off

Connecting in the panel is simple - not sure why the electric utility needs to come out to do it. The ground wire enters the dwelling and then goes into the panel box and is connected to the grounding lug strip - where neutral is also connected. I was doing a subpanel however, so the neutral is left disconnected from the ground.

The point of the ground rod is to tie the neutral to local ground potential. If you did not have this the ground and neutral in your building neutral would float. You wouldn't want it to be different than the actual ground potential (shocks)

I believe you can measure your ohms to ground pretty simply with a supply voltage hooked to a resistor to the ground rod. It gives you a voltage divider.

 

[Tubetec]

My guess is the 1.2m spec here in Ireland is based on the fact that the soil is pretty damp the whole year round .
I certainly could have made the connection to the earth terminal myself , but the original earth cable bonds to another larger gauge terminal thats enclosed and tamper proof sealed by the ESB (electricity supply board).
I was hoping when the guy came out he might test the new and old ground and explain the methodology they use .

To be honest I'd just assumed a good low impedence connection to ground would mean less chance of any noise voltages appearing .

Fuse board here was updated to modern spec around 25 years ago ,electronic breakers on everything , ELCB is still a common term used here , its been a while since I was in school learning about such things ,terminology may well have moved on , but the basis of it is still two coils , one on the live one on the neutral any faults currents to earth cause an imbalance and it trips out , thats my limited understanding .

 

[JohnRoberts]

I believe you can measure your ohms to ground pretty simply with a supply voltage hooked to a resistor to the ground rod. It gives you a voltage divider.

and what is that supply voltage grounded to?
==
I am uncomfortable pontificating too much but from decades of paying attention, the mains power poles all have ground conductors going down into the earth at their base. The stepdown transformer centertap gets bonded to neutral and the residential ground at the breaker panel. If they specify a specific ohms number, perhaps between the residential ground conductor and the utility pole ground conductor, but this is just my WAG. The transformer CT may be bonded to the utility pole ground conductor but I DO NOT KNOW THAT FOR A FACT.

I did a quick web search for authoritative info and found several web sites I am unwilling to link to.

Your utility will know what they want, a good electrician should know (can't say I ever met one of those in MS).

JR

 

[Matt Syson]

As mentioned previously grounding is about electrical safety, not 'noise'.Bonding of the Neutral from the service cables (underground or overhead) to the 'ground (soil) that you would be standing on and to all metallic pipework (water, gas etc) so that as far as possible whatever you grab at your property there will be next to no voltage difference 'available'.
If course as all conductors are aerials (transmitting or receiving) depending on the frequency (wavelength) one end of any wire may not be the same AC potential as the other. At microwave frequencies a wire around 6 inches (150mm or so) can have maximum signal at opposite ends.
Of course mains is 50 Hz (60 in USA and Japan) and te wavelength is very long (someone else can say how long!). The relevance of mentioning the 'aerial' properties is that ground may NOT be ground at HF. The overriding thing is that you follow your local electrical safety code for legality.

 

[dmp]

and what is that supply voltage grounded to?

Good point, the same ground. Not sure of a DIY ways

They make meters:
https://www.fluke.com/en/product/electrical-testing/earth-ground/fluke-1630

 

[Matt Syson]

Seeing JR's contribution, UK and the EU generally do not have centre tapped power wiring. It is usually if not always 3 phase and the Neutral is grounded locally. This then leads to Earth leakage breakers. There are small differences across the EU but all 'modern' installations should have 30 milliamp 'differential' breakers (various names used). Thus the live conductor must be 'balanced' by the returning 'Neutral conductor current. This neatly brings me to the fact that all wiring is CURRENT (impedance) balanced thus meaning you don't need power balancing transformers for 'balanced power'. If the live current is different to the Neutral current your breakers will have already shut the power off. Twisted pair (normal typical mains cable with or without earth conductor is therefore already balanced although admittedly twisting the live and neutral conductors more tightly would reduce magnetic 'field radiation more.

 

[JohnRoberts]

Here they are called GFCI ground fault circuit interrupters (built into outlets), I believe yours are called RCD (residential current something or other) built into panels for protecting entire branches.

Thus the obvious difficulty giving mains safety advice to different parts of the world.

Check with your local utility.

JR

 

[PermO]

Don't try this at home;

 

[abbey road d enfer]

"I believe you can measure your ohms to ground pretty simply with a supply voltage hooked to a resistor to the ground rod. It gives you a voltage divider. "

and what is that supply voltage grounded to?

AFAIK, what's measured is the resistance between the ground spike and the Neutral wire from the supplier. Which does not necessarily make sense...

 

[dmp]

It looks like with the right meter the measurement is the resistance through the ground rod


(go to 49 sec)

 

[abbey road d enfer]

In case of the stage, a big metal construction in an open field, sitting on wooden boards on the grass and the only ground connection is a 30cm copper pipe ?
I'm talking lightning protection here.
The regulations for a temporary safety ground on a stage are the same as the one for your house and I don't think a 30cm copper pipe is a sufficient ground connection in case of a lightning strike.

I'm not sure having the stage earthed via a single copper wire makes a big difference when lightning strikes...

 

[abbey road d enfer]

It looks like with the right meter the measurement is the resistance through the ground rod

This is an impedance measurement, which is done in reference to the ground mesh constituted by all the grounds interconnected on the continent.
https://www.fluke.com/en-us/learn/blog/grounding/stakeless-method

 

[JohnRoberts]

I'm not sure having the stage earthed via a single copper wire makes a big difference when lightning strikes...

Lightning is complicated and best you can do is steer it... or prevent it by dissipating the charge. Power poles have a mature lightning management system.

Lightning hit one of my tall pine trees last year and the down strike jumped from the tree to a nearby power line (actually a grounded support cable) about 20' from the ground. That harmlessly dissipated the strike energy, and the tree is still alive. While the upper trunk split and got damaged. The initial up-strike that attracted the down-strike came all the way up from the tree roots/earth. If the entire down-strike went into the roots it might have killed the tree.

JR

 

[CJ]

I remember a thread called ,my
Hot water heater by John that had some good stuff