The series "Step-by-Step Panel" offers a practical approach to creating a safe and efficient electrical panel. It consists of three stages: planning, selection, and installation. Following this sequence will protect your wiring from overloads and short circuits while also providing extra capacity for future devices.
Often, homeowners or beginner electricians install "the breaker at hand" without calculating the load. The result can be overheating, no reserve capacity, and sometimes even fire. Our approach provides a complete roadmap: first, calculate the load and cable cross-section → then choose the rated modular circuit breaker and other protective devices.
Main Stages of Creating an Electrical Panel: Overview of the "Step-by-Step Panel" Series
For a distribution panel to operate reliably, you need to complete three stages:
- Load planning – calculating power, grouping consumers, determining reserve;
- Component selection – choosing modular circuit breakers, RCDs, RCBOs, voltage relays (UEC);
- Panel installation – correct mounting of the enclosure, cable routing, testing.
An error at any stage can cause problems such as:
- incorrect cable cross-section → overheating;
- wrongly selected circuit breaker → no protection;
- poor installation → sparking and accidents.
Therefore, it’s important to consider the process comprehensively: from load planning to post-installation testing.
Planning
Make a list of all devices and sum up the power of lighting, sockets, kitchen, and heating appliances:
- Apartment 50 m² → 8–10 kW;
- House 150 m² → 15–18 kW.
These figures allow you to calculate the nominal current using the formula: I = P/U (where P is the total power, U is the mains voltage 230 V according to the standard).
Grouping Consumers
Next, divide devices into groups:
- sockets;
- lighting;
- high-power individual appliances (water heater, stove, air conditioner).
For a 50 m² apartment, 6–8 groups are needed; for a 150 m² house, 12–16. Grouping evenly distributes the load across phases and minimizes overload risks. It is important to provide separate UEC circuit breakers for critical devices so that when a protection device trips, the entire system is not de-energized.
Load Reserve
Include a 20–30% reserve so that new consumers can be added in the future without replacing cables or breakers. Leave 2–4 free modules in the panel.
Choosing the Type of Panel
Planning also involves selecting the panel type: modular, wall-mounted, or embedded. According to building codes (DBN), the panel must be convenient for maintenance and comply with fire safety standards. Embedded UEC panels are typically chosen for apartments, while wall-mounted or modular panels with expansion options are preferred for private houses.
Correlation of Cable Cross-Section and Breaker
The main rule is: first determine the cable cross-section, then choose the breaker and other UEC devices needed for its protection.
Component Selection
Once load planning and cable sizing are done, the next step is the proper selection of all key electrical panel components.
Modular Circuit Breakers
The main purpose of a UEC breaker is to protect the cable from overload and short circuit. It is important to select the correct rated current and trip characteristic (B, C, or D):
- B — for loads without high inrush currents (lighting, sockets);
- C — for household appliances with moderate inrush currents (pumps, air conditioners);
- D — for high-power equipment with large inrush currents (machines, compressors).
Certified UEC breakers meet IEC/EN standards and reliably trip during short circuits.
Residual Current Devices (RCD) and RCBOs
The next step is selecting an RCD or RCBO to protect people from electric shock. Recommended sensitivity is 30 mA for wet rooms and main socket groups. Choose the correct type according to the load:
- AC — for standard AC loads;
- A — for electronic devices and household appliances with switching power supplies.
An RCBO combines a breaker and RCD in one module, saving space.
Voltage Relay
Disconnects the line in case of critical voltage drops or surges, protecting electronics.
Practical Example of Component Selection (Kitchen Socket)
Suppose a kitchen socket group is planned for a microwave, coffee maker, toaster, and small appliances. The total expected peak power is P = 4500 W.
- Choose the cable cross-section. Approximate allowable currents for copper conductors (typical conditions, normal temperature, single line): 1.5 mm² — ≈ 15–18 A; 2.5 mm² — ≈ 20–25 A; 4 mm² — ≈ 25–32 A; 6 mm² — ≈ 32–40 A. For P = 4500 W and line length up to 15 m — use 2.5 mm²; for longer routes — 4 mm².
- Calculate nominal current: I = P/U = 4500/230 ≈ 19.6 A.
- Select the UEC breaker: 2.5 mm² → C25; 4 mm² → C32.
- Choose trip characteristic: B, C, or D. For socket groups — C; for high inrush current — D; for lighting — B.
- Select RCD/RCBO: 30 mA for human protection; type A for electronics; combined C25/30mA (type A) for space-saving and protection.
Important! Use certified UEC modular breakers and RCDs — "noname" components may fail during a short circuit.
Installation
Installing the electrical panel is the final stage, where mistakes can compromise the entire system’s safety. Live work is strictly prohibited for beginners.
Preparation and Safety
- Completely disconnect the network and check with a tester;
- Wear PPE: insulating gloves, safety glasses, non-slip shoes;
- Prepare the panel diagram and list of groups.
Tools for Panel Installation
- Insulated screwdrivers;
- Torque wrench;
- Voltage tester, megohmmeter;
- Wire cutters, strippers, WAGO connectors / crimp sleeves;
- Markers, labels for line marking.
Step-by-Step Installation
- Mount the panel enclosure on the wall or niche (level properly);
- Fix the DIN rails;
- Install modules in logical order: main breaker → RCD or RCBO → group breakers → additional modules (voltage relay, contactors);
- Connect cables according to the diagram and color code;
- Tighten all terminals with a torque wrench — loose contact = risk of overheating;
- Connect grounding to the PE bus;
- Label all lines — stickers/labels are mandatory.
Testing and Verification
- Check for short circuits;
- Measure insulation resistance;
- Test switching of breakers;
- Press TEST button on RCD (should trip immediately);
- Recheck all connections.
Even if you are confident in your skills, some stages are better entrusted to a certified electrician, especially for:
- Official commissioning (residential, office, industrial);
- Preparation of measurement protocols and documentation;
- Doubts about installation correctness or component selection.
Conclusion
Organizing a reliable electrical panel always starts with a plan. First, calculate loads, distribute groups, and include a 20–30% reserve for future expansion. Next, select the correct cable cross-section and matching breaker with the appropriate trip characteristic. In wet and critical areas, use an RCD or RCBO rated at 30 mA.
Installation completes the process: all lines should be labeled, terminals securely tightened, and the panel tested using the TEST button and control measurements.
Remember:
- The UEC breaker protects the cable, not vice versa;
- Always provide a reserve;
- Line labeling simplifies maintenance;
- Regular protection checks ensure fire safety.
Your workflow is simple: list devices → I = P / U → choose cable cross-section → select breaker and protective devices → install and test. Skipping any step may lead to chaos in the distribution panel, cable overloads, and potential overheating. Don’t wait: make your load list today and check whether installed breakers match the cable cross-section.
