What is the most important thing about grounding

Equipotential bonding and earthing

"This is how you can safely handle electricity in the building"

Whether residential building, commercial building or industrial production facility - today no building can do without electricity. And beyond ensuring the actual building functions, residents, visitors or employees use electricity in a wide variety of forms in a variety of activities. So that the steadily increasing Electrification of buildings but with the necessary certainty it can come Equipotential bonding and earthing of elementary importance when building a house.

Equipotential bonding and earthing - why, how, where?

Every object has a certain electrical potential. It doesn't even have to be electrically operated. Surely everyone has already had the experience that, especially in extremely cold and at the same time dry weather, touching the doorknob, a railing or other metallic objects causes a slight but easily perceptible electric shock. Nothing else takes place here than equipotential bonding between objects with different electrical charges.

The larger the object and the better its electrical conductivity, the higher the potential for electrical charging. The same applies to electrically operated devices, as the electricity for charging is even supplied in a targeted manner by means of a cable from the socket. It always becomes critical when the equipotential bonding happens in an uncontrolled manner and the potential difference to be compensated is so great that a simple electric shock can result in a real danger. At the latest when the discharge of the equipotential bonding leads to the formation of sparks, the risk of fire increases exponentially. It is therefore important to derive potential differences early and in a targeted manner. This is always done via the so-called grounding, i.e. the dissipation of energy from the electrically charged object into the earth. The only difference is that the derivation takes place in a targeted and controlled manner and not unintentionally and spontaneously.

The requirement of equipotential bonding when building a house

Why are suitable earthing systems so important in house construction? This question is easy to answer. Where the proverbial balloon and wool sweater only achieve a very low level of electrical charge, which, however, is also clearly noticeable, a building of any type, on the other hand, has a much higher potential for the creation of electrical charges. First of all, almost the entire structure is electrified via the distribution lines and the various customers in the building. In addition to the familiar power lines, this also includes network lines, television cables and all other live lines. In addition to permanently installed or permanently available electricity consumers, such as heating, refrigerator and washing machine, there is an unmanageable number of small pantographs in every building, from kettles to PCs and cell phone charging cables. In total, however, they also result in serious dangers due to a different electrical potential. In addition to the actual current-carrying components and devices, a large number of other conductive components also offer considerable opportunities for electrical charges. Just think of sewer pipes made of metal, which on the one hand run through the entire building and on the other hand are regularly electrically charged by running water.

The second main reason why buildings in particular need effective earthing is the particularly good insulation of the building fabric today. It is true that this is primarily a matter of thermal and acoustic insulation, but the building materials used for this are usually just as suitable for electrical insulation.

Starting with floating screeds on completely insulating layers of insulation, through the barely conductive building materials masonry, concrete and wood, to the entire floor slab, which today is often insulated from below against the ground, is often even shielded in several layers.

Earth contact as a basic requirement for equipotential bonding

But this is exactly where the great danger with buildings lies. On the one hand, these are particularly charged electrically due to the internal loads. On the other hand, because of the good shielding against the ground, there is often no natural and permanent equipotential bonding. This results in a particularly high risk in the event of uncontrolled equipotential bonding, since a large amount of electrical energy can be released at certain points. Large here means at least a current strength which, in the worst case, can lead to the formation of sparks and thus to fire development.

The most important basic requirement for the electrical equipment of every building is therefore the creation of a functioning earthing. It creates a permanent connection to the subsurface so that any voltages that arise can flow away without being able to develop a critical current at all.

Earthing systems - the different paths of electrical potential into the ground

In order to ensure the contact between the electrical installations and the underground, some simple and effective earthing systems have been established.

The foundation earth electrode

The so-called foundation earth electrode is well-known and proven many times over. Since the foundations need direct contact with the ground in order to fulfill their static function, a conductive metal strip is simply but effectively inserted into the foundation concrete. Usually this is made of galvanized steel, or even stainless steel. In the vicinity of the main fuse box, this foundation earth electrode is led upwards out of the concrete in the form of a metal strip. A suitable equipotential bonding rail can then be used to connect the further electrical installations.

Alternative earthing systems for insulated floor slabs

In particular, the increasingly effective insulation measures are increasingly causing problems for the classic foundation earth electrode. In the past, basement floors were mostly not insulated at all, but today the entire floor slab is increasingly placed on a layer of insulation. Foundations are completely obsolete in favor of a thicker base plate. If an earth tape is inserted into the concrete here, the benefit for equipotential bonding is gone because of the shielding effect of the insulation layer. Instead, a metal grid or band must be led through the insulation layer directly into the soil below. Alternatively, an earth spike can be guided vertically into the ground at certain points. However, this must be large enough to form an adequate replacement for the foundation earth electrode that is no longer required.

The creation of equipotential bonding - what must be connected to the ground?

Once the earth contact has been ensured, all relevant devices and components must be connected to the equipotential bonding rail. It's pretty easy for electrical devices. The main distributor is connected directly, from which the grounding is then carried out via the third wire of the classic power cable in the building. If a plug is plugged into the socket, grounding is automatically established via the protective conductor. It is more difficult with non-electrical components. Metal lines, for example, must be connected separately using grounding clamps. Depending on the complexity of the line network, one or more grounding clips may be required. Further examples of objects that have to be connected to the ground are the buffer storage and possible existing gas and oil tanks for the heating, but also the downpipes and rain pipes on the outside of the building.

Conclusion - equipotential bonding and earthing - there is no getting around them when building a house

No building can function without electricity and no electricity in the building without grounding. This makes it clear, in a nutshell, that a functioning equipotential bonding is a basic requirement for every building to function. Therefore, when planning the electrical system, the effort for a well thought-out and targeted planning is worthwhile. If errors occur here, they cannot be remedied later, or at least only with great effort. In most cases, however, grounding problems lead to permanent restrictions in usability.

Electrical grounding grounding accessories installation equipotential bonding current2018-09-24