Why Is Copper Grounding Wire Buried Deep Instead of Left as Bare Wire Above Ground?

Because the hoop is galvanized and will not rot as quickly as a regular cord. Among others.

grzesdc wrote:

Because the hoop is galvanized and will not rot as quickly as a regular cord. Among others.

The copper wire will not "rot" either

kosmonauta80 wrote:

Why can't it be just a bare wire? Why bury it so deep? The idea is to remove the dangerous charge under the surface due to the negligible (compared to the ground) resistance of the hoop iron?

Because the earth electrode must have parameters, because the ground close to the surface is quite susceptible to weather conditions and other external factors (e.g. a shallowly buried hoop in winter may simply freeze along with the ground)

The point is, my dear friend, that in the event of a threat (whether from lightning or damage to the insulation), there was no shock / damage / loss of life to both your person and bystanders in the place. The protection also includes devices and electrical installations that may be damaged - but this is a secondary matter in a life-threatening situation.
I will give you an example like this:
In a situation where, for example, your insulation is damaged and you can see a conductor (copper or aluminum), when the current flows through it, some of it may flow out of the conductor and be on a conductive material, e.g. a metal table - then the working person within it is exposed to electric shock.
The characteristic of the current is that it does not like to be difficult and it flows on the best way, i.e. the way where the resistance is the lowest.
In the above situation, if such an installation is equipped with a protective conductor (yellow-green), the current escaping from the conductor, located on this table, will flow through the protective conductor that is connected to the hoop. Then it will swim to the ground, killing two gates at the same time - a joke. On the way, an appropriate residual current device will work to cut off the voltage. However, in order for the current to flow to the ground, there must be appropriate protection parameters which include this earth electrode. In order for the parameters (resistance) of the earth electrode to be appropriate, the hoop also should be buried deep enough and measurements should be made on it. If the resistance is high (probably more than 10? - appropriate regulation / standard), the earth electrode is enlarged to maintain these parameters.
If the earth electrode sucked, the current would be reluctant to flow to the ground and a person could be electrocuted.
That is why the hoop must be buried so deep.

As for the depth of the hoop in the ground - recently I did, the hoop was dug to a depth of about 1.2 m. Length of the hoop in the ground (vertically and horizontally) 4m. 130? resistance. Condition 10 ? not fulfilled. To this attached hoop iron pins were attached that went vertically to the ground (the total length of the pins is 4.5 m). In such an earth electrode, the resistance dropped to 4 ?, which was obviously confirmed by measurements.
What mate? Now the contractor can sleep well without fear of being hit by something :)

Here are some photos of the earth electrode that was dismantled and replaced with a new one - unfortunately I do not have photos on this lap:


And here is such a curiosity for you:


Think a little, what will be better in the above situation: steel hoop or cable?

Therefore, the steel in the hoop is of appropriate quality and parameters, e.g. the basic section is 30x4mm. If someone designs an earth electrode, e.g. for an industrial hall, the grating (coopers connected with each other forming geometric figures, e.g. rectangles) is properly compacted with a given cross-section so that the electric shock voltage is sufficiently low. An ordinary piece of whatever you do not throw in, because the measurements will not come out, unless you falsify it, but it's a different story.
In PL, a galvanized steel hoop is used which meets the relevant requirements and standards (PN-EN 50164-2) classifying it as suitable for placing it in the ground. In the west, copper hoops are used - higher cost compared to steel ones. With us, this custom will not be accepted for a long time because the investor keeps every zloty on the account because the% is growing

kivors wrote:

Miniax wrote:

e.g. a shallowly buried hoop can simply freeze along with the ground in winter)

And what if it freezes, loses its conductive properties or what?

You almost guessed. What in the ground completes the electric circuit between the hoop and the elements of the remaining earth electrodes? Water. Does ice have the same conductive properties as water? Seriously, the standard says about burying the hoop at a depth of at least 40 cm (unless something has changed now), so that freezing does not really matter. But the depth of the earth electrode is influenced by min. soil moisture - in dry sand it will not fulfill its task.

kivors wrote:

And what if it freezes, loses its conductive properties or what?

First of all, the hoop is subjected to quite large temperature changes, it will "tire" and will be damaged quite quickly. Secondly, in the event of freezing, the parameters of the earth electrode change.

JohnySpZOO wrote:

As for the depth of the hoop in the ground - recently I did, the hoop was dug to a depth of about 1.2 m. Length of the hoop in the ground (vertically and horizontally) 4m. 130? resistance. Condition 10 ? not fulfilled. To this attached hoop iron pins were attached that went vertically to the ground (the total length of the pins is 4.5 m). In such an earth electrode, the resistance dropped to 4 ?, which was obviously confirmed by measurements.

In electric shock protection, the value of the earth resistance is NOT significant. Earthing resistance cannot exceed 10 Ohm in lightning and overvoltage protection.

It buries itself below the freezing point because objects that freeze with a layer of soil tend to "pop out of the ground" (such as shallowly buried corpses in crime movies . After a few winters, such a cooperage could be shallowly underneath or lie on the ground.

Piotr Sz. wrote:

It buries itself below the freezing point because objects that freeze with a layer of soil tend to "pop out of the ground" (such as shallowly buried corpses in crime movies . After a few winters, such a cooperage could be shallowly underneath or lie on the ground.

What is the level of freezing right now?

Well, there is still corrosion. In addition, insulation of foundations began to be introduced. Ie. the entire area (sides, bottom, interior) of the foundation is cut off from the ground. Is it then also used as a grounding hoop in a foundation bench because, as colleagues wrote, that it should act as grounding, there must be moisture.

Why the cooperage so deep ?? - Why the LV and HV cables so deep ??
Besides, the deeper the soil, the lower the soil resistivity. And why a cooperage and not a cord? Because it is the cheapest, I cannot imagine using a copper wire with a cross section of 120mm.

Arturo2005 wrote:

What is the freezing level right now?

Map

Miniax wrote:

In electric shock protection, the value of the earth electrode resistance is NOT IMPORTANT. Earthing resistance cannot exceed 10 Ohm in lightning and overvoltage protection.

yes, completely irrelevant, especially in TT networks (because you can always add a light theory to TN ...) and since it is irrelevant, the grounding resistance may be infinitely large, so grounding may not be

I suggest to my colleague go back to the basics and find out what grounding is and what is the difference between grounding and grounding (and at the "advanced" level, point out the differences between the earthing switch and the earthing switch) and do not spread heresy

stasiekm wrote:

yes, completely irrelevant, especially in TT networks (because you can always add a light theory to TN ...) and since it is irrelevant, the grounding resistance may be infinitely large, so grounding may not be

I suggest to my colleague go back to the basics and find out what grounding is and what is the difference between grounding and grounding (and at the "advanced" level, point out the differences between the earthing switch and the earthing switch) and do not spread heresy

Calculate the earthing resistance value that is sufficient to trip an RCD normally used in domestic installations (30mA).
In the TT network, the entire protection hangs practically on the differentials, so it is enough for the earthing resistance to be such that in the event of a breakdown, a current "large" enough to the housing will make the differential work. Unless you want the ESCs to work, but then I wish you good luck in designing the grounding so that it triggers even B16 or C16 in a "normal" time, not to mention the higher protection values.

Piotr Sz. wrote:

Arturo2005 wrote:

What is the freezing level right now?

Map

Quote:

It buries itself below the freezing point because objects that freeze with a layer of soil tend to "pop out of the ground" (such as shallowly buried corpses in crime movies . After a few winters, such a cooperage could be shallowly underneath or lie on the ground.

According to my colleagues, all cables or hoops would be on top a long time ago

Arturo2005 wrote:

According to my colleagues, all cables or hoops would be on top a long time ago

Maybe we don't watch crime movies enough.

kisses
- GIFT-

For TT, the earth electrode is prepared in such a way as to trigger S-type protections, so it oscillates around 1R, if there are differentials, the current is much smaller, and thus the resistance may be higher, but the RCD is not a "cure for all evil" and it is used as a supplementary protection for obvious reasons - it is unreliable. TT is a special case :)

For TT with a permissible voltage of 50V and protection B16, to maintain the SWZ, the earth resistance should be 0.63R