When it comes to wiring a car, garage or home workshop, the circuit breaker C16 is becoming one of the most popular solutions. But many car owners and craftsmen are faced with the question: “What power is this machine designed for and how to use it correctly?” The answer is not as simple as it seems - the mains voltage (220V or 380V), the type of load (reactive or reactive), and even the ambient temperature play a role here.

In this article we will look at real power that the C16 automatic can withstand in various conditions, and not just theoretical numbers from the passport. You will find out why the same machine in a garage at 220V “holds” 3.5 kW, but at a welding station at 380V it already holds 10 kW. We will also analyze typical connection errors that lead to false alarms or, worse, fire due to cable overheating. If you plan to connect powerful equipment - from a compressor to a battery charger - this information will help you avoid costly miscalculations.

What does the “C16” marking on a machine mean?

The letter and number in the designation of a circuit breaker carry key information about its characteristics. Let's decipher them:

  • 🔤 Letter "C" - this is response characteristic (time-current curve). Type machines C operate at currents exceeding the nominal value by 5–10 times. This is the best option for most household and garage networks where short-term inrush currents are possible (for example, from a compressor motor or welding machine).
  • 🔢 Number "16" - this is rated current in amperes (A), at which the machine can operate indefinitely without shutdown. Exceeding this value by 13–45% (depending on temperature) will cause the thermal release to trip.

It is important to understand that C16 is not equivalent to 16 A in any conditions. For example, at a temperature of +40°C in a garage, the machine can operate at 14–15 A due to overheating, and at –20°C it can “hold” up to 18 A. Manufacturers indicate the rating for standard conditions (+30°C), but actual values ​​can vary greatly.

One more nuance: the machine protects not the load, but the cable. Its task is to prevent overheating of the wiring, not the equipment. Therefore, the selection of a machine should always be after choosing the cable cross-section, and not vice versa.

📊 Where do you plan to use the C16 assault rifle?
In the garage
In the home workshop
For car service
For street lighting
Other

Power calculation for the C16 machine at 220V and 380V

The power that the C16 machine can “pull” depends on the network voltage and the type of connected load. Let's consider two main cases:

1. Single-phase 220V network

For active loads (heaters, lamps, power supplies), the power is calculated using the formula:

P = U × I × cosφ

Where:

  • P — power (W);
  • U — voltage (220V);
  • I - current (16 A);
  • cosφ — power factor (for active load ≈ 1).

Substitute the values:

P = 220 × 16 × 1 = 3520 W (3.5 kW)

However, for reactive loads (electric motors, transformers, welding machines) cosφ maybe 0.7–0.8. Then:

P = 220 × 16 × 0.7 ≈ 2464 W (2.5 kW)

2. Three-phase network 380V

In a three-phase network, the C16 machine is usually installed on one phase (for example, in a garage panel). Power is calculated taking into account load distribution:

P = √3 × U × I × cosφ

For active load:

P = 1.73 × 380 × 16 × 1 ≈ 10.5 kW

But this total power for three phases. If the machine is on one phase, its maximum load will be:

Pphase = 380 × 16 × 1 ≈ 6.1 kW

For a reactive load (such as an asynchronous motor), the power is reduced to:

Pphase = 380 × 16 × 0.8 ≈ 4.8 kW
💡

The C16 circuit breaker in a three-phase 380V network can withstand up to 6.1 kW of active load on one phase, but the actual value depends on the cosφ of the equipment.

Power table for the C16 machine depending on voltage

Network type Voltage, V Load type Max. power, kW Equipment examples
Single phase 220 Active (cosφ = 1) 3,5 Heater, 12V power supply, LED panels
Single phase 220 Reactive (cosφ = 0,7) 2,5 Compressor, grinder, drill
Three-phase (1 phase) 380 Active (cosφ = 1) 6,1 Welding machine (household), charger
Three-phase (1 phase) 380 Reactive (cosφ = 0,8) 4,8 Asynchronous motor, machine tool
Three-phase (3 phases) 380 Active (cosφ = 1) 10,5 Three-phase heater, server equipment

Please note: the values in the table are theoretical maximum. In real conditions it is necessary to take into account:

  • 🔥 Ambient temperature (at +40°C the power is reduced by 10–15%).
  • 🔌 Quality of contacts (bad terminals can heat up and reduce the permissible current).
  • ⚡ Starting currents (for example, a compressor motor consumes 3-5 times its rated value when starting up).

What cable cross-section is needed for the C16 machine?

The machine protects cable, not the connected equipment. Therefore, the wire cross-section must correspond machine's nominal value, and not the load power. For the C16 machine, the recommended cable sections are:

Core material Section, mm² Max. current, A Recommendations
Copper 1,5 19 Suitable for short lines (up to 10 m) in dry rooms
Copper 2,5 27 The optimal choice for most cases (garage, workshop)
Aluminum 4 21 For fixed wiring only, not recommended for moving connections

Why can’t I use a 1.5 mm² cable with a C16 machine? Although it is suitable for current (19 A), in real conditions two risks are possible:

  1. Overheating due to poor contact in the terminal block (especially if the cores are stranded).
  2. Voltage drop on long lines (more than 15 m), which will lead to a lack of power received by the equipment.

For a garage or car service where high starting currents are possible, it is better to choose copper cable 4 mm² - this will provide a current reserve and reduce heating.

💡

If the cable length from the shield to the socket exceeds 20 meters, increase the cross-section by one step (for example, instead of 2.5 mm², take 4 mm²) to avoid voltage drop.

Typical errors when connecting a C16 machine

Even experienced electricians sometimes make mistakes that lead to false alarms or, more dangerously, lack of protection. Let's look at the most common ones:

⚠️ Attention: Connection neutral working conductor (N) through the C16 machine is strictly prohibited! This violates the requirements of the PUE and can lead to electric shock when a phase is disconnected.
  • 🔌 Incorrect terminal connections. The phase wire must fit top terminal of the machine, and move away from bottom. An inverted connection is not prohibited by regulations, but may cause problems with heat dissipation.
  • 🔥 Using a machine as a switch. Frequent manual shutdown of C16 leads to wear of the mechanism and false alarms. For these purposes you need contactor or relay.
  • ⚡ Ignoring inrush currents. For example, a 2.2 kW compressor motor at startup can consume up to 10–12 A, which is close to the C16 response threshold. The solution is to use a machine with the characteristic D (for example, D20) or install soft starter.
  • 📉 Failure to take temperature into account. In a hot garage in the summer, the machine can operate at a load of 12–13 A. The solution is to use machines with temperature compensation or increase the rating to S20 (but only if the cable allows it!).

Another common mistake is parallel connection of several C16 machines on one line. This leads to uneven load on the phases and the risk of voltage imbalance. If you need to power several powerful consumers, it is better to use one machine of a higher rating (for example, S25) with the appropriate cable.

The machine is installed in a vertical position (not on its side)|The phase wire is connected to the top terminal|Cable cross-section is at least 2.5 mm² for copper|The neutral wire does not pass through the machine|The terminals are securely tightened (checked with a screwdriver)-->

Is it possible to replace a C16 automatic machine with a C20 or C25

Many people believe that replacing the machine with a more powerful one will solve the problems with false positives. But this is a dangerous misconception. Increasing the machine's denomination does not increase the permissible power of the cable - it only increases the risk of overheating and fire.

Let's consider two scenarios:

  1. Cable 2.5 mm² + automatic machine C20:
    • Permissible cable current: 27 A.
    • Machine rating: 20 A.
    • Risk: at a current of 25 A, the cable heats up, but the machine does not operate (20 A < 25 A < 27 A). This leads to the destruction of insulation.
  • Cable 4 mm² + automatic machine C16:
    • Permissible cable current: 38 A.
    • Machine rating: 16 A.
    • Risk: the machine will trip at the slightest overload, although the cable can withstand more.

      • Conclusion: The rating of the machine must correspond to the cable cross-section, not the load. If you really need more power:

      1. Replace the cable with a thicker one (eg 4 mm² instead of 2.5 mm²).
      2. Install a machine with a rating corresponding to the new cable (for example, S25 for 4 mm²).
      3. Check whether the input machine and meter can withstand the increased load.
    What happens if you put a C25 machine on a 1.5 mm² cable?

    At a current of 20–25 A, a 1.5 mm² cable will overheat, the insulation will melt, which will lead to a short circuit. The C25 machine will only work at a current of 30+ A, when the wire is already on fire. This is one of the main causes of fires in garages and workshops.

    Practical examples: what equipment can be connected to C16

    To make it easier to navigate, we give specific examples of equipment that can be safely connected to a C16 machine with the correct cable cross-section:

    For a single-phase 220V network:

    • 🔧 Compressor (2.2 kW, cosφ = 0,8) - will require taking into account starting currents (it is better to use S20 or soft starter).
    • 🔥 Infrared heater (3 kW) - active load, ideal.
    • 🚗 Battery charger (15 A, 3 kW) - check if the instructions contain requirements for the cable cross-section.
    • 💡 LED spotlights (500 W) - the load is minimal, the machine protects the cable from short circuit.

    For a three-phase network 380V (single phase):

    • 🔨 Welding machine (5 kW, cosφ = 0,7) - suitable, but check the starting currents.
    • 🔄 Lathe (4 kW, asynchronous motor) - you will need an automatic machine with the characteristic D.
    • 🔋 Inverter power supply (6 kW) is a resistive load, but check the peak currents.

    For equipment with high inrush currents (e.g. engines, compressors, pumps) it is better to use:

    • Automata with characteristics D (for example, D20).
    • Soft starters or frequency converters.
    • Separate lines with increased cable cross-section.

      • FAQ: Frequently asked questions about the C16 assault rifle

      Is it possible to connect three phases to C16?

      No, the C16 automatic is designed for one phase. For a three-phase load, you need to use a three-pole circuit breaker (for example, 3P C16), where each pole protects its own phase. In this case, the total power will be limited to the most loaded phase.

      Why does C16 trip at a load of 2 kW?

      The reasons may be as follows:

      1. Machine malfunction (check on another line).
      2. High temperature in the shield (more than +40°C).
      3. Poor contact in the terminals (heating → false operation).
      4. Starting currents of equipment (for example, a refrigerator or compressor).

      Solution: check the tightness of the terminals, measure the temperature in the panel, if necessary, replace the machine with S20 (if the cable allows it).

      Which machine should I put in a garage with sockets and lighting?

      For a typical garage with:

      • Lighting (0.5 kW),
      • Sockets for tools (2 kW),
      • Charger (1 kW)

      enough:

      • Input machine: S25 (if the total load is up to 5 kW).
      • For sockets: C16 with 2.5 mm² cable.
      • For lighting: C10 with 1.5 mm² cable.
      What is the difference between C16 and B16?

      The main difference is time-current characteristic:

      • C16 - triggers at currents of 5–10 × In (16 A), suitable for mixed loads (lighting + motors).
      • B16 - triggers at currents of 3–5 × In, used for active loads (heaters, lighting) without inrush currents.

      For garage or workshop C16 preferable, as it better tolerates short-term overloads.

      Is it necessary to install an RCD with a C16 machine?

      Yes, if the line feeds:

      • Sockets in damp areas (garage, basement).
      • Equipment with a metal body (machines, compressors).
      • Outdoor electrical installations (spotlights, cameras).

      Recommended RCD: 25 A, 30 mA (to protect against electric shock). For the introductory machine you can use RCD 40 A, 100 mA (fire protection).