Distribution board for an apartment: a complete guide to selection and installation

An electrical panel in an apartment is not just a box with automatic machines, but security control center the entire home electrical network. Whether your equipment will be protected from overloads and your wires from short circuits depends on its correct selection and installation. In 2026, the requirements for residential switchboards have become more stringent: now even for a typical one-room apartment, a couple of automatic devices and an RCD are not enough - a well-thought-out system is needed, taking into account modern loads (electric vehicles, powerful heaters, smart home).

In this article we will analyze all stages of work with the distribution board - from choosing a case to testing the assembled circuit. You will find out what place machines on socketswhy differential switches better than conventional RCDs in some cases, and how to prevent typical error with "phase imbalance" when connecting a three-phase shield. The material is adapted for beginners, but also contains expert nuances - for example, how to calculate the cross-section PEN- conductor for the system TN-C-S.

1. Why do you need a switchboard in an apartment: functions and standards

The main task of the apartment panel is electricity distribution by consumer groups (sockets, lights, appliances) and their protection. According to PUE 7.1.22 (current edition 2026), the shield must:

• 🔌 Provide selective shutdown - in case of an accident, it knocks out only the problematic line, and not the entire apartment.
• ⚡ Protect from overloads (automatic machines) and current leakage (RCD / automatic devices).
• 📊 Allow electricity metering (place for the meter if it is not located in the entrance).
• 🔧 Be accessible to inspection and repair — the door must open without tools.

In apartment buildings, the shield also plays a role delimitator of responsibility: everything up to the meter (inclusive) is the service area of the management company, after the meter is yours. The exception is houses with a TN-C-S system, where grounding is organized through a shield on the floor, and not in the apartment.

⚠️ Attention: In houses older than 2003, switchboards without protective grounding are often found (PE). Connect modern appliances (washing machines, ovens) to such networks prohibited - requires upgrading to TN-C-S or TT.

2. Types of distribution boards for an apartment: which one to choose

Shields are divided according to three key parameters: body material, installation method and number of modules. Let's consider each criterion in detail.

2.1. Case material: plastic vs metal

Parameter	Plastic shield	Metal shield
Cost	⭐ 30–50% cheaper	⭐⭐⭐ More expensive, but more durable
Resistance to mechanical damage	Low (cracks on impact)	High (suitable for garages, workshops)
Fire safety	Self-extinguishing plastic (class V-0)	Does not burn, but heats up during short circuit
Weight	Lightweight (1–3 kg)	Heavy (5–15 kg)
Where to use	Apartments, offices	Private houses, industrial premises

Optimal for a typical apartment plastic shield (for example, ABB Mistral 65 or Schneider Electric Kaedra). Metal boxes (IEK KMPn) are relevant if the shield is installed in room with high humidity (bathroom, basement) or requires increased protection from vandals.

2.2. Installation method: surface-mounted or built-in

• 🔨 Overhead shield - attached to the wall with dowels. Pros: easy installation, can be installed on drywall. Cons: takes up space, less aesthetic.
• 🏗️ Built-in shield - recessed into the wall (requires a niche). Pros: neat appearance, saves space. Cons: more difficult to install, requires wall preparation.

In 90% of apartments they install built-in panels — they fit harmoniously into the interior. Overhead options are chosen for temporary schemes (for example, for the period of renovation) or if the walls do not allow making a niche (panel houses with thin partitions).

2.3. Number of modules: how to calculate

A module is a conventional unit of width (17.5 mm) occupied by one machine or RCD. To calculate the number of modules:

1. Count consumer groups (for example: kitchen sockets, room sockets, light, washing machine, air conditioner).
2. Add introductory machine (1–2 modules) and counter (6–8 modules if it is inside the shield).
3. Please note reserve — at least 20% free modules for future changes.

Example for a 2-room apartment:

Input machine: 2 modules
Counter: 6 modules
RCD 30 mA: 2 modules
Group machines (8 pcs.): 8 × 1 = 8 modules
Reserve (4 modules)
TOTAL: 22 modules → select a shield for 24 modules (for example, Hager TD24).

3. Switchboard equipment: which machines and RCDs to install

The heart of the shield is modular protection devices. Their choice depends on network type (single-phase/three-phase), loads and safety requirements. Let's look at each element.

3.1. Input machine: characteristics and rating

The introductory machine is installed to the counter (if the counter is inside the shield) or after him (if the meter is at the entrance). His tasks:

• ⚡ Disable the whole apartment when the permissible power is exceeded.
• 🔧 Open the circuit for safe repair.

The rating of the input machine depends on allocated power for an apartment:

Power allocated (kW)	Machine rating (A)	Machine type
3.5–5.5	25	Single phase (1P)
7–10	40	Single phase (1P)
10–15	50	Single-phase (1P) or three-phase (3P)
15+	63	Three-phase (3P)

Sufficient for most apartments single-phase circuit breaker 40 A (for example, Legrand DX³ 40A). If the house is new and connected using a three-phase circuit, they install three-pole circuit breaker (for example, ABB S203 C63).

⚠️ Attention: Denomination of the introductory machine should not exceed throughput power cable from the floor board. For example, if the riser is made with cable VVGng 3×10 mm² (max. 50 A), set the machine to 63 A it's impossible - this will lead to overheating of the wiring.

3.2. RCD vs difavtomat: which is better for an apartment

Both devices protect against current leakage (for example, when there is an insulation breakdown in a washing machine), but they work differently:

• 🔄 RCD - only triggers in case of leakage, but does not protect against overloads. Requires a pair with a machine gun.
• ⚡ Difavtomat — combined device (RCD + automatic device in one housing). Takes up less space, but is more expensive.

What to choose?

• 🏠 For small-sized panels (up to 18 modules) — difavtomats (save space).
• 🔧 For complex circuits with many groups - RCD + automatic machines (cheaper and easier to replace a separate element).

Example of reliable models:

• RCD: Schneider Electric Acti9 iID (30 mA, type A).
• Difavtomat: Hager AD120 (16 A, 30 mA, characteristic C).

3.3. Automatic machines for group lines: ratings and characteristics

Circuit breakers for groups are selected according to load current and type of characteristic:

• 🔌 Sockets: automatic C16 (for living rooms) or C20 (for the kitchen where powerful appliances are connected).
• 💡 Lighting: automatic B10 or C10 (sufficient, since the lamps consume little).
• 🔥 Electric stove/oven: automatic C32 (if power is up to 7 kW).
• ❄️ Air conditioning: automatic C16 (up to 3.5 kW).

Characteristics B suitable for purely active loads (lamps, heaters), C - for mixed loads (sockets, refrigerator), D - for starting currents (pumps, compressors).

Make sure that the rating of the input machine does not exceed the power allocated to the apartment |

Check the compatibility of RCDs/devices with automatic machines (in terms of current and characteristics) |

Leave a reserve of modules (minimum 4 pieces) for future changes|

Choose a shield with the possibility of sealing (if the meter is inside) -->

4. Distribution board diagrams: examples for 1-, 2- and 3-room apartments

A competent shield design should take into account:

• 📌 Division into groups — each line is protected by a separate machine.
• 🔗 Selectivity — in case of an accident, only the problem group is switched off.
• ⚡ Load balance — for three-phase shields, the phases are distributed evenly.

4.1. One-room apartment (single-phase network)

Typical diagram for a "odnushka" with a power of up to 7 kW:

Input machine (40 A) → Meter → RCD 40 A/30 mA (type A) →
├── Automatic C16 (kitchen sockets)
├── Automatic C16 (room sockets)
├── Automatic C10 (lighting)
└── Automatic C20 (washing machine)

Features:

• 🔹 One common RCD for the whole apartment (saves space).
• 🔹 The washing machine is separated into a separate group with an automatic machine C20.

4.2. Two-room apartment (single-phase network)

Scheme with separate RCD for “wet” zones:

Input machine (50 A) → Counter →
├── RCD 40 A/30 mA (bathroom + kitchen) →
│ ├── Automatic C16 (kitchen sockets)
│ └── Automatic C20 (washing machine)
└── RCD 25 A/30 mA (living rooms) →
├── Automatic C16 (room sockets)
└── Automatic C10 (lighting)

Why so:

• 🚿 RCD separation increases safety - if there is a leak in the bathroom, the lights in the rooms do not turn off.
• 🔌 Kitchen sockets protected separately (there is the highest load).

4.3. Three-room apartment (three-phase network)

Scheme for an apartment with an electric stove and air conditioners:

Input machine 3P (40 A) → 3-phase meter →
├── Difavtomat C16/30 mA (phase A: room sockets)
├── Difavtomat C20/30 mA (phase B: kitchen + washing machine)
├── Difavtomat C25/30 mA (phase C: electric stove)
└── Automatic C10 (lighting, connected evenly to phases A/B/C)

Key points:

• ⚖️ Phase balance: the load is distributed so that the current in each phase does not exceed 16–20 A.
• 🔥 Electric stove connected via difavtomat 25 A (cable 5×4 mm²).

⚠️ Attention: In three-phase switchboards Single-phase consumers cannot be connected to two phases simultaneously (for example, a socket between phases A and B). This will lead to phase-to-phase short circuit when the load is turned on.

What is “phase imbalance” and why is it dangerous?

In a three-phase network, the current must be distributed evenly between the phases. If one phase is overloaded (for example, a stove and heater are “hung” on it), and the others are underloaded, a problem occurs. skew. This leads to:

- Voltage drop in an overloaded phase (lamps dim, equipment operates unstable).

- Increased voltage on underloaded phases (risk of equipment failure).

- Overheating of the neutral wire (N) and fire.

In apartment panels, distortion is eliminated correct load distribution by phase at the circuit design stage.

5. Installation of the distribution board: step-by-step instructions

Shield installation can be divided into three stages: preparing a niche, assembling modules and connecting wires. Let's look at each step with photos and tips.

5.1. Site preparation and tools

To install a built-in panel you will need:

• 🔨 Tools: hammer drill with crown Ø68 mm, grinder, level, screwdrivers.
• 📏 Materials: shield, cable VVGng-Ls, corrugation, dowel clamps, DIN rail.
• 🛡️ Protective equipment: dielectric gloves, glasses, voltage tester.

Sequence of niche preparation:

1. Mark on the wall shield outline (width/height tolerance - +5 mm).
2. Using a hammer drill with a crown, drill holes around the perimeter.
3. Using a grinder, cut the bridges between the holes.
4. Deepen the niche on 70–80 mm (depth of a standard shield).
5. Blow dust out of the cavity and prime it.

5.2. Shield assembly: order of installation of modules

Modules are mounted on DIN rail in the following order (from left to right):

1. Introductory machine (if the counter is inside the shield, then after the counter).
2. RCD/difavtomatic devices (group by zones: kitchen, bathroom, rooms).
3. Linear automata (sockets, lights).
4. Zero and ground buses (bottom or top of the shield).

Installation rules:

• 🔗 Connection of machines carry out comb (for example, ABB PS 1/12), rather than jumpers - it’s more reliable.
• 🔴 Phase wires connect from above, zero - from below (unless otherwise indicated in the instructions).
• 📏 Wire stock length in the shield - 15–20 cm (for possible reconnection).

5.3. Wiring and commissioning

Connection algorithm:

1. Route the cables into the panel through input seals (dust protection).
2. Remove the insulation from the wires (10–12 mm for automatic machines, 15 mm for the tire).
3. Connect phase wires to the machines (observe the color markings: brown/black - phase, blue - zero, yellow-green - ground).
4. Place the neutral wires on zero bus, grounding - on PE bus.
5. Check no short circuits tester.
6. Turn on the input machine and test every line load (for example, a lamp).

⚠️ Attention: After assembling the shield be sure to check the RCD operation "Test" button. If the RCD does not turn off, it means that it is faulty or incorrectly connected (a common mistake is that the zero and ground are mixed up).

6. Typical mistakes when assembling a shield and how to avoid them

Even experienced electricians sometimes make mistakes that later lead to false positives, overheating or fire. Let's look at the top 5 mistakes and ways to prevent them.

6.1. Wrong choice of machine denominations

Error: Machine selected according to consumer power, not by cable cross section.

Example: A cable is laid for an outlet in the kitchen VVGng 3×2.5 mm² (max. current 25 A), but an automatic machine is installed C32. With a load of 25–30 A, the cable will overheat and the machine will not work.

How to avoid:

• Use table of sections from the PUE (for example, for 2.5 mm² max. automatic - C20).
• For long lines (more than 30 m) take a cable with a spare cross-section.

6.2. Lack of module reserve

Error: The shield is assembled end-to-end with no free spaces. When adding a new outlet or appliance, you have to change the shield completely.

How to avoid:

• Always leave minimum 4 free modules (preferably 6–8).
• Choose shields with removable side walls - they can be built up later.

6.3. Incorrect RCD grouping

Error: All sockets in the apartment are connected to one 30 mA RCD. If there is a leak in the bathroom, the lights in the entire apartment are turned off.

How to avoid:

• Separate the RCD by risk areas:

  - Bathroom + kitchen - one RCD.

  - Living rooms are another RCD.

• For refrigerator and freezer use RCD with response delay (selective).

6.4. Ignoring wire markings

Error: Wires are connected without color coding, which complicates repairs and increases the risk of errors.

Correct marking:

• 🟤 Yellow-green - grounding (PE).
• 🟦 Blue - working zero (N).
• 🟠/⚫ Brown/black - phase (L).

6.5. Poor grounding

Error: Ground wire not connected to the PE bus or connected via jumper (for example, to the zero bus).

Consequences:

• ⚡ Risk of electric shock due to insulation breakdown.
• 🔥 Fire due to overheating of the neutral wire.

How to avoid:

• All PE-connect the wires directly to the ground bus.
• In houses with a system TN-C (without grounding) necessarily organize the transition to TN-C-S.

7. Shield maintenance: checking and replacing elements

A switchboard is not a “set it and forget it” thing. He demands periodic maintenance, especially if the load in the apartment often changes (for example, you bought a powerful heater or an electric car).

7.1. When to check the shield

Scheduled checks are carried out by:

• 📅 Once every 6 months — visual inspection (no melting or foreign odors).
• 🔧 Once every 2 years — checking the operation of the RCD using the “Test” button.
• ⚡ After a thunderstorm or power surge - testing of machines.
• 🏠 When purchasing new equipment (for example, an air conditioner) - checking the power reserve.

7.2. How to test RCDs and automatic machines

To check the RCD:

1. Click the button "Test" - a shutdown should occur.
2. If the RCD does not work, replace it - it faulty.

To check machines:

• Unplug all appliances.
• Turn on the machine and connect the load (for example, an iron).
• If automatic false alarm, check:

  - Quality of contacts (tighten terminals).

  - So