Electrical panel with RCD and automatic switches is not just a box with wires, but the basis for the security of your home or garage. An incorrectly assembled circuit can result in short circuits, fires, or even electric shock. In 2026, the requirements for electrical installations have become more stringent: now even to connect a powerful welding machine in the garage or a charging station for an electric car, you need a well-designed circuit taking into account selectivity and rated currents.

In this article we will look at three proven shield assembly schemes - from a simple single-line for an apartment to a complex multi-level for a private house with three-phase input. You will learn how to choose RCD (by leakage current and type: AC, A, B), which machine guns put on sockets, lighting and powerful consumers (for example, a compressor or machine in the garage), and how to avoid the most dangerous installation errors - for example, when an RCD trips falsely due to incorrect connection of the neutral wires. At the end you will find an FAQ with answers to questions most often asked by new electricians.

1. Basic diagram of a panel for an apartment: what should be inside

If you live in a standard apartment with a single-phase input (220V) and a power of up to 10 kW, the simplest circuit will suit you. Its main elements:

  • 🔌 Introductory machine (typically 32–50 A, depending on allocated power). It protects the entire circuit from overload and short circuit.
  • ⚡ RCD or differential circuit breaker (at 30-100 mA for general protection and 10-30 mA for wet areas). For example, ABB FH202 or Schneider Electric Acti9 iID.
  • 💡 Vending machines for consumer groups: sockets (16 A), lighting (10 A), powerful appliances (20–25 A). For a garage, add a separate 25-32 A line for the tool.
  • 🔗 Ground bus (PE) and zero bus (N). Important: they should not be confused!

A typical diagram looks like this:

  1. Input cable → input machine → meter (if it is inside the panel).
  2. Counter → general RCD (30–100 mA).
  3. RCD → group circuit breakers (one for each line).
  4. From the machines, wires go to sockets, switches and other consumers.
📊 What type of shield do you have installed?
Single phase (220V)
Three-phase (380V)
Not installed yet
I don't know

For a garage or workshop, the circuit needs to be modified: add a separate 10 mA RCD for wet areas (if there is a sink) and a 25–32 A circuit breaker for powerful equipment (welding machine, compressor). For example, if you have in your garage Karcher or Metabo, their power supply must go through a separate line with a machine C25 and RCD 30 mA type A (since the instruments have electronics).

2. How to choose an RCD: 5 criteria that cannot be ignored

A residual current device (RCD) saves you from electric shock and fire, but only if it is selected correctly. Here's what to look for:

Parameter Recommendations for the apartment Recommendations for garage/home
Leakage current (mA) 10 mA - bathroom, kitchen; 30 mA - other lines 10 mA - wet areas; 30–100 mA - general protection
RCD type AC — for simple loads (lamps, heaters) A or B — if you have electronics (welding inverter, car charger)
Rated current (A) One step higher than the automatic machine (for example, automatic machine 16 A → RCD 25 A) The same, but with a reserve (automatic 25 A → RCD 40 A)
Manufacturer ABB, Schneider Electric, Legrand Hager, Siemens (for severe conditions)

⚠️ Attention: If the garage contains old equipment with high leakage currents (for example, a Soviet machine tool), a 10 mA RCD will trigger falsely. In this case, either change the equipment or install a 30 mA RCD, but with additional protection (grounding, insulation).

For three-phase networks (380V) in a house or garage you need four-pole RCD. For example, ABB DS202 C40/0.03 (40 A, 30 mA). It is connected after the introductory circuit breaker, but before the group RCDs for individual phases.

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If there is not enough space in the shield, use differential automata (RCD + automatic device in one housing). For example, Schneider Electric DX³ 16A/30mA. They are more expensive, but save space and simplify installation.

3. Three-phase panel for a house or garage: selectivity circuit

If you have a private house with a three-phase input (380V) or a garage with powerful equipment (welding machine, compressor, electric car charger), you need a more complex circuit. Its key feature is selectivity: in the event of an accident on one line, only that line is switched off, and not the entire house.

An example diagram for a house with a garage:

  1. Input machine (3×50 A) → meter → fire protection RCD 100–300 mA (for example, Hager CD440).
  2. Three phases go from the fire protection RCD to group RCDs (30 mA per phase).
  3. From group RCDs - automatic machines on separate lines:
    • 🏠 House: sockets (16 A), lighting (10 A), boiler (20 A).
    • 🚗 Garage: sockets (16 A), lighting (10 A), welding machine (25–32 A), compressor (20 A).
  • To charge an electric vehicle (for example, Tesla or Nissan Leaf) you need a separate line with a machine C25 and RCD 30 mA type A.

    • Selectivity is achieved through:

    • 🔹 RCD with delay (labeling S or G). For example, ABB DS951.
    • 🔹 Cascade connection: first general RCD (100 mA), then group (30 mA).
    • 🔹 Correct selection of denominations: the input machine must be more powerful than the group ones.
    What is selectivity in practice?

    If an outlet in the garage shorts out, only the circuit breaker on that line will work, and not the entire panel. Without selectivity, a short circuit in the welding machine can turn off the lights in the entire house.

    ⚠️ Attention: In three-phase networks one should not confuse neutral working wire (N) and zero protective (PE). If you combine them after the RCD (the so-called “zeroing”), the device will trigger falsely or will not protect against electric shock at all. This is a common mistake when connecting garage equipment!

    4. Step-by-step installation of the panel: from marking to connection

    You can assemble the shield yourself if you follow the instructions. You will need:

    • 🔧 Screwdrivers (phillips, flat).
    • 🔨 Drill (for attaching the shield to the wall).
    • 📏 Level and roulette.
    • 🔌 Crimper for crimping tips (for example, Knipex PZ 63>).
    • 🔍 Multimeter (to check voltage).

    Disconnect the input circuit breaker (check the absence of voltage with a multimeter) |

    Mark locations for the panel and cable ducts|

    Prepare the wires (strip, crimp with lugs) |

    Check the equipment (automatic machines, RCDs, tires)|

    Take a photo of the old circuit (if the panel is being modernized) -->

    Step 1. Install the shield. Attach the case to the wall (optimal height is 1.5–1.7 m from the floor). For a garage, choose a shield with a protection class of at least IP44 (dust- and moisture-proof).

    Step 2. Installation of DIN rails and busbars. Install:

    • DIN rails for automatic machines and RCDs.
    • Ground bus (PE) - must be isolated from the housing.
    • Zero bus (N) - if there are several RCDs, separate buses are needed for each.

    Step 3. Connecting the input circuit breaker and RCD. First connect the phase (L) to the input machine, then zero (N) - to the RCD. In a three-phase network, the phases are connected in order A-B-C (usually from left to right).

    Step 4. Connecting group machines. From the RCD, the phase goes to the machines, and the zero goes to the corresponding zero bus. Never combine zeros of different RCDs - this will lead to false alarms!

    Step 5. Check. Turn on the input machine and test each line one by one. To check the RCD, use the button TEST (Shutdown should work).

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    The most common installation mistake is incorrect connection of the neutral wires. If you confuse N and PE or combine zeros of different RCDs, the circuit will not work correctly.

    5. Common mistakes and how to avoid them

    Even experienced electricians make mistakes sometimes. Here 5 most dangerous mistakes when assembling a panel with RCDs and automatic machines:

    1. Lack of selectivity. If all the machines are of the same rating, in the event of an accident the entire house may shut down. Solution: use machines with different operating currents (for example, input C50, group C16–C25).
    2. Wrong choice of RCD. RCD type AC will not protect modern electronics (for example, an inverter welding machine). Solution: for a garage, take an RCD type A or B.
    3. Overload of one phase in a three-phase network. If you put all powerful consumers (boiler, washing machine, compressor) on one phase, it will heat up. Solution: distribute the load evenly across phases.
    4. Use of low-quality machines. Cheap machines (for example, IEK or EKF) may not work if there is a short circuit. Solution: take it ABB, Schneider Electric or Legrand.
    5. Lack of markings. In a year you will forget which machine does what. Solution: Label each machine with a marker or use stickers.

    ⚠️ Attention: If there is old aluminum wiring in the garage or house, it cannot be directly connected to modern machines (due to the difference in the resistance of the materials). Use terminal blocks (for example, Wago 222-413) or completely replace the wiring with copper.

    6. Shield maintenance: when and how to check

    The panel with RCD and automatic circuit breakers requires regular maintenance. Here's what to do:

    • 📅 Once a month: press the button TEST on the RCD - it should turn off. If not, the device is faulty.
    • 📅 Once every six months: tighten the screw connections (they loosen over time).
    • 📅 Once a year: check the input voltage with a multimeter (should be 220–230V for a single-phase network or 380–400V for a three-phase network).
    • 📅 Once every 5 years: replace the RCD (even if it works, sensitivity is lost over time).

    If the shield is installed in a garage or workshop, check it more often - once every 3 months. Dust, moisture and vibration from equipment accelerate contact wear.

    ⚠️ Attention: If the RCD trips for no apparent reason, do not ignore it! Possible reasons:

    • Current leakage in the wiring (for example, damaged insulation).
    • Malfunction of a household appliance (most often a washing machine or boiler).
    • Incorrect connection of neutral wires (see section 4).

    To find the problem, turn off all devices and turn them on one by one, observing the RCD.

    FAQ: Answers to frequently asked questions

    Is it possible to install one RCD for the entire apartment?

    It is possible, but not advisable. One 30–100 mA RCD is enough to protect against fire, but it will not provide safety in the bathroom or kitchen. Optimal: general RCD (100 mA) + separate ones at 10–30 mA for wet areas.

    What is the difference between RCD type AC by type A?

    RCD type AC responds only to alternating leakage current (for example, from a heater). Type A also triggered by pulsating direct current (from electronics: computers, welding inverters, car chargers). For a garage it is better to take the type A.

    Do you need an RCD for lighting?

    According to the PUE standards (7th edition), an RCD for lighting is not necessary, but is recommended in wet rooms (bathroom, garage). For ordinary chandeliers in the living room, a 10 A circuit breaker is sufficient.

    How to connect an RCD in a three-phase network?

    In a three-phase network, a four-pole RCD is used. Phases A, B, C and zero N are connected to the corresponding terminals. After the RCD, the phases go to group circuit breakers, and the zero goes to a separate bus. Important: You cannot combine zeros of different RCDs!

    Is it possible to assemble the shield yourself without experience?

    If you do not have experience, it is better to invite an electrician. Errors in panel assembly may result in fire or electric shock. The best thing you can do yourself is to replace the circuit breaker or RCD (after turning off the input circuit breaker).