Grounding: What it is, why it is needed, and how to do it right

Grounding a house is one of the key elements of electrical safety, protecting residents from electric shock and ensuring the safety of electrical devices. In this article, we will look at what grounding is, why it is necessary, how it works, and how to properly install it in a private home.

What is grounding?

Grounding is a system that connects electrical devices or elements of a building to the ground via a conductor in order to divert excess electrical energy into the ground in the event of a short circuit, lightning strike, current leakage, or other electrical equipment malfunctions.

House grounding system – installation of a grounding circuit for electrical network safety in Ukraine — SP Premier company

How does grounding work?

When excess voltage occurs, the current flows through the grounding conductor to the grounding device and dissipates into the ground. In modern grounding systems, it often works in conjunction with RCDs — protective shutdown devices that instantly cut off the power supply when a current leak is detected.

Why is grounding necessary?

Human safety. If there is a fault in the electrical network (e.g., damage to insulation), current can flow to the appliance casing. Without grounding, a person touching such a casing could receive a fatal electric shock. Grounding diverts this current into the ground, minimizing the risk.
Protection of electrical appliances. Grounding helps prevent damage to electrical appliances from power surges.
Protection from static electricity. Grounding dissipates static electricity that can accumulate on the body of appliances, preventing damage.
Grounding of lightning rods (lightning protection). If the appropriate equipment is available, it ensures the safe discharge of lightning current into the ground, preventing damage to buildings and equipment.
Compliance with standards. In many countries, including Ukraine, grounding is mandatory according to building and electrical standards, such as the Rules for the Installation of Electrical Installations (Правила улаштування електроустановок).

Inverters and solar generators must be grounded to protect against electric shock, overload, and damage due to overvoltage. Now that more and more people are using these devices due to frequent power outages, the issue of proper grounding is becoming particularly relevant for their safe and reliable operation.

Types of grounding

By type of grounding device:

Natural grounding. Natural metal structures located in the ground are used: water pipes, metal foundations, etc.
Artificial grounding. It is created specifically by installing metal grounding devices (rods, strips) in the ground.

By grounding systems:

TN-S — the distinctive feature of this system is that the neutral conductor (N), which returns current to the power source, and the protective conductor (PE), which serves for grounding and protection against electric shock, are completely separated along the entire path from the transformer to the end consumer. The most reliable and safest option.
TN-C — this grounding system is simpler and less safe compared to TN-S. In it, the neutral (N) and protective (PE) conductors are combined into a single common conductor called PEN (protective earth neutral) along the entire path from the power source to the consumer. TN-C was often used in older buildings and networks, but is now considered obsolete and is being replaced by newer systems.
TN-C-S is a hybrid of TN-C and TN-S. In this system, the neutral (N) and protective (PE) conductors are combined into a single PEN conductor from the power source to a certain point (e.g., the input panel), as in TN-C. Further, from this point to the consumer, the PEN is separated into separate neutral (N) and protective (PE) conductors, as in TN-S.
IT — a grounding system characterized by the fact that the neutral point of the power source is either isolated or grounded through high resistance, and the protective grounding (PE) of the consumer is connected to a local grounding circuit. This ensures high reliability: when the first ground fault occurs, the network continues to operate and the leakage current is minimal. It is used in critical facilities (hospitals, mines), but requires constant monitoring of insulation and RCDs (residual current devices).
TT — this grounding system is distinguished by the fact that the protective grounding (PE) of the consumer is connected to a local grounding circuit that is independent of the neutral (N) of the power source. The neutral (N) on the transformer side is grounded separately, and the protective conductor (PE) on the consumer side is connected to its own grounding, such as a grounding rod or circuit. It is often used in private homes where it is not possible to use grounding from the power source, but it requires careful design and maintenance.

For private homes, it is recommended to use a TT or TN-S system, depending on local conditions and connection options.

Basic elements of grounding

An grounding system, such as TT, consists of the following components:

Grounding device — metal elements (rods, pipes, or plates) that are buried in the ground.
Grounding conductor — a cable that connects the grounding device to the grounding busbar, electrical panel, or specific device.
Grounding circuit — a set of grounding electrodes located in the ground for better current distribution.
Main grounding busbar — the point where all grounding wires are connected in a building. Located in the input-distribution device (IDD).
Lightning protection is an additional element for diverting lightning current, consisting of a lightning rod, a current conductor (grounding conductor), and a grounding device.

SP Premier grounding devices for installing a grounding circuit in a house in Ukraine

Grounding of a private house with an area of 100–150 m²

For a modern private house with an area of 100–150 m², the recommended grounding resistance values depend on the type of power supply and grounding system:

Grounding resistance standards

For TN-C-S systems (the most common in modern homes), the grounding resistance must not exceed 4 ohms. This value ensures the safe operation of protective devices such as RCDs (residual current devices) and current diversion in the event of a fault.
For the TT system, the resistance is also recommended to be up to 4 ohms, but can be up to 30 ohms if an RCD with a sensitivity of 30 mA is installed, which provides protection against electric shock.
The grounding resistance for a lightning rod should not exceed 10 ohms (according to State standard of Ukraine — ДСТУ Б В.2.5-38:2008). If the circuit is combined with protective grounding, the most stringent standard of 4 ohms should be used as a guide.

For industrial facilities, grounding resistance depends on the class of electrical installations. For electrical installations up to 1000 V, it must not exceed 4 ohms, and for those above 1000 V, it must not exceed 0.5 ohms.

Why 4 ohms?

This value ensures that in the event of a short circuit or current leakage, circuit breakers or RCDs will operate quickly and effectively.
ЧThe lower the grounding resistance (in ohms), the faster and more efficiently the current is discharged into the ground.
For a house of 100–150 m² with modern equipment (electric stove, air conditioners, electric floor heating, boiler, etc.) and a power of 10–15 kW, this is a standard value.

How to achieve 4 ohms?

For a house of 100–150 m², the following is usually sufficient:

3–5 rods (2–3 m long, 16–20 mm in diameter), driven into the ground in a triangle or line formation.
Connections with a 40x4 mm steel strip or copper conductor, which conducts electricity best.
Location in a moist area (e.g., near a drain).
If the resistance after installation exceeds 4 ohms, add more electrodes or use chemical soil conductivity enhancers.

How to install artificial grounding in your home?

Step 1: Planning

Determine the location for the grounding rod. It should be moist (but not flooded) and accessible for maintenance. Keep it away from walkways and areas where people frequently gather.
Check the soil type: sandy soil has higher resistance than clay or ordinary soil, so more grounding rods may be needed.

Step 2: Selecting materials

Grounding device (electrode): Steel rods with a diameter of at least 16 mm or copper plates, or ground screw piles. The length of the rods is 2-3 meters.
Conductor: Copper cable with a cross-section of at least 10 mm².
Fastening: Plates, pins, locking nuts, bolts, clamps for a secure connection.

If you have no experience in electrical installation, it is better to consult a qualified specialist. The grounding system must also be checked and certified by a specialist from the power company.

Step 3: Installation

Dig a triangular hole or trench 0.5-1 m deep.
Drive the grounding rods into the ground to a depth of at least 2.5 m, arranging them in a triangle with a distance of 1-2 m between them.
Connect the grounding rods to each other with a welded metal profile.
Connect the grounding conductor to the circuit and run it to the main distribution board.
In the board, connect the wire to the main grounding busbar.

Step 4: Checking

Measure the grounding resistance with a special device (megohmmeter). The norm is up to 4 ohms for household networks.
Make sure that the system works together with the RCD.

Grounding mistakes

Mistakes when installing grounding can lead to dangerous situations, such as electric shock, damage to electrical appliances, overheating, or even fire. Here are the most common mistakes related to grounding:

Wrong choice of location for the grounding device. For example, when the grounding rod is installed in dry soil with high resistance (such as sand), which reduces the effectiveness of grounding. To improve the effectiveness of grounding in such soil, a more complex design and longer rods are required.
Incorrect choice of grounding conductor. The use of small cross-section wires or materials that do not meet the requirements (e.g., aluminum instead of copper) can cause overheating and damage the grounding system.
Breakage or corrosion of the grounding conductor. If the grounding conductor is broken or severely corroded, the effectiveness of the grounding is lost.
Insufficient depth or number of grounding rods. If the grounding rods are not installed deep enough or there are not enough of them, the grounding resistance may be too high and the effectiveness of the grounding will be low, which may cause the protective devices to fail or respond with a delay.
Use of structures unsuitable for grounding. Old foundation reinforcement, pipes, or other metal structures without checking their electrical continuity can lead to ineffective grounding or even dangerous situations.
Poor contact between elements. Oxidation, poor bolt tightening, or soldering can increase contact resistance, which can cause overheating and grounding failure.
Incorrect connection of grounding circuits can damage equipment and disrupt the power grid, or pose a danger to human life. Therefore, it is necessary to comply with the requirements of the «Rules for the Installation of Electrical Installations».

Grounding your home is not just a technical formality, but a vital system that ensures safety and comfort. Properly designed and installed grounding can save lives and protect property from accidents, and the entire house from fire. If you are building or renovating your home, do not ignore this step — investing in safety always pays off.

If you need reliable and safe grounding, contact SP Pemier! We offer high-quality design and installation of grounding for homes, businesses, and industrial facilities, ensuring compliance with all safety standards and requirements. Contact us for a consultation and to order grounding installation!