TN and its varieties

The most common type of grounding system is TN, in which the zero is aligned with the ground along its entire length. This type of supply is also called dead grounded neutral when the conditional source N is connected to the PE earthing device. The grounding device is not difficult, but nevertheless technically advanced and represents a set of nails that are driven vertically into the ground to a great depth into the underground tank, from 2.5 meters or more. These pins are connected to a ribbon or cable in a single ground loop of an apartment building. Consider the classification of TN systems that exist today and what is the difference between all the varieties.

TN-C

Old housing uses TN-C protection type, this is when the neutral conductor N also acts as a PE protective conductor. This is the easiest and cheapest option for grounding electrical installations up to 1000V.

Type TN-C is outdated and electrically dangerous, because it does not have a separate protective conductor, and if a neutral wire is broken during an emergency, the full potential will be on the electrical equipment, presenting the risk of electric shock or fire.

TN-S

Therefore, in newly designed buildings, another subsystem is used. TN-S, this device has a separate wire, zero (neutral) and a PE protection conductor. Conductors N and PE, starting from a substation with a grounded neutral, are separate components of the power supply system.

This type is the most reliable of the accepted types of grounding for the electrical network. Its disadvantages include high cost, as it needs an additional conductor from the substation to the consumer.

TN-CS

Devoid of these drawbacks, the TN-CS system is relatively easy to implement, which combines the advantages of the previously described systems. It is also easily implemented during the reconstruction of old buildings. The meaning of this scheme is that the TN-C system is organized before the main switchboard, and here the PEN neutral wire is divided into two conductors N and PE, followed by the TN-S system.

The disadvantage of this system is the same as TN-C, when the PEN bus is broken, the system is under full voltage. They struggle with this by installing additional devices, such as a voltage relay that produces an emergency disconnection of the consumer from the network.

TT and IT

There are two more types of supply that are used in special circumstances, this type TT – when the electrical energy connection is organized by phase wires from a source with a grounded neutral, and the grounding is organized directly on the consumer. In this way, connect mobile homes and temporary objects.This type requires the use of residual circuit breakers.

Another option is an IT system, supply type that does not use a dead earthed neutral. The source zero is connected through special devices with high internal resistance, and a zero and protective grounding device is installed directly on the consumer (according to PUE 7, Chapter 1.7). This type of supply is used in private laboratories, because the interference introduced in this way is limiting lowest.

Finally, we want to pay attention – it is forbidden to use heating pipes, gas pipes, water pipes and metal fencing elements as a protective floor. In this case, it is possible that a full voltage of 220 V may appear on these elements, endangering the lives of others. take care of yourself.

That’s all I wanted to tell you about the main types of grounding systems. We hope you now know what type of grounding circuits exist and what the differences are between the current options!