Circuit breakers on 63 amps - one of the most popular in household and industrial electrical networks. They are installed at the entrance to private houses, garages, workshops and even in apartments with high load (for example, when connecting electric stoves or powerful machines). But how do you understand how many kilowatts can a 63A automatic machine withstand? in a single-phase network 220V or three-phase 380V? The answer depends on the type of connection, the power factor of the load and even the ambient temperature.

Many people mistakenly believe that it is enough to multiply amperes by volts and you will get the desired value. In practice, one has to take into account starting currents (for example, for electric motors they are 5–7 times higher than rated), cable section (to avoid overheating of the wiring) and machine type (B, C or D). In this article we will analyze all the nuances of the calculation, provide ready-made tables and tell you how to avoid mistakes when choosing a 63A machine.

A 63A circuit breaker is not just a β€œswitch”, but a complex device that protects the network from short circuits and overloads. Its rating (63A) indicates the maximum continuous current, which it can pass through without shutting down. However, if this value is exceeded by 13–45% (depending on trip characteristics) the machine will work in a few seconds or minutes. But in the event of a short circuit, the shutdown occurs instantly - in a fraction of a second.

It is important to understand that 63A β‰  63 kW. Power (kW) and current (A) are related through voltage (V), but the formula is not as simple as it seems. For example, in a single-phase 220V network, a 63A automatic circuit breaker will theoretically withstand up to 13.86 kW (63A Γ— 220V), but in practice this figure needs to be adjusted taking into account power factor (cos Ο†) and ambient temperature. In a three-phase 380V network, the calculation is even more complicated - the load connection diagram (star or delta) plays a role here.

Formulas for calculating power for a 63A machine

To accurately determine how many kilowatts can a 63A automatic machine withstand?, use two basic formulas - for single-phase and three-phase networks. Important: these formulas give maximum theoretical power, but the actual load should be 20–30% lower to avoid false positives.

For single-phase network 220V: 

P = U Γ— I Γ— cos Ο†

where:

- P β€” power in watts (W),

- U - voltage (220V),

- I - current (63A),

- cos Ο† β€” power factor (for household appliances usually 0.9–0.95, for engines 0.7–0.8).

Example: if cos Ο† = 0.9, then: P = 220 Γ— 63 Γ— 0.9 β‰ˆ 12,474 W or 12.47 kW.

For three-phase network 380V (with symmetrical load): 

P = √3 Γ— U Γ— I Γ— cos Ο†

where √3 β‰ˆ 1.73, and U = 380V.

When cos Ο† = 0.8:

P = 1.73 Γ— 380 Γ— 63 Γ— 0.8 β‰ˆ 32,300 W or 32.3 kW.

However, these numbers are theoretical maximum. In practice, you need to consider:

  • πŸ”Œ Starting currents: for engines, compressors or welding machines they are 3–7 times higher than the nominal ones. For example, a 5 kW motor may consume 25–35 kW at startup.
  • 🌑️ Temperature: at +40Β°C the machine will operate at a lower current than at +20Β°C.
  • πŸ“Š Characteristics of the machine: type B, C or D determines at what excess current a shutdown will occur.
πŸ“Š What type of machine do you have installed at the input?
B (3–5Γ—In)
C (5–10Γ—In)
D (10–20Γ—In)
I don't know

Power table for 63A machine: 220V vs 380V

Below is a table with calculated power values for a 63A machine at different coefficients cos Ο† and network types. This data will help you quickly assess what load can be connected without the risk of tripping the protection.

Network type cos Ο† Max. power (kW) Recommended load (kW)
Single phase 220V 1.0 13.86 10–11
Single phase 220V 0.9 12.47 9–10
Single phase 220V 0.8 11.09 8–9
Three-phase 380V 0.95 40.3 30–35
Three-phase 380V 0.8 32.3 25–28

Please note: in the column "Recommended load" values indicated are 20–30% below the maximum. This is due to the fact that:

  1. The machine may operate under prolonged load close to the nominal value (due to heating).
  2. Inrush currents of equipment (for example, circular saw or compressor) can exceed the nominal values several times.
  3. The cable also has a current limit and its cross-section must be suitable for the load.
πŸ’‘

A 63A circuit breaker in a single-phase 220V network can safely withstand up to 10–11 kW of constant load (at cos Ο† β‰ˆ 0.9). For a three-phase 380V network, this figure rises to 25–30 kW.

Cable cross-section for a 63A machine: how to avoid mistakes

One of the most common mistakes when choosing a machine is mismatch of cable cross-section with the machine's rating. For example, if you connect a 6 mmΒ² cable to a 63A circuit breaker (maximum current for copper is 46A), the wiring will overheat, which will lead to a fire. Therefore, the cable cross-section should be no less, than required for a current of 63A.

For copper cable at a temperature of +25Β°C, minimum cross-sections:

  • πŸ”Ή Single-phase network (220V): 16 mmΒ² (max. current 76A).
  • πŸ”Ή Three-phase network (380V): 10 mmΒ² (max. current 60A) - but it is better to take 16 mmΒ² with a margin.

For aluminum cable, the cross-section should be 1–2 sizes larger (for example, 25 mmΒ² instead of 16 mmΒ²).

When choosing a cable, also consider:

⚠️ Attention: If the cable is laid in a corrugation or in a bundle with other wires, its permissible current is reduced by 20–30%. In such cases, the 63A machine may require a cross-section of 25 mmΒ² (copper) instead of 16 mmΒ².

Cable cross-section β‰₯ 16 mmΒ² (copper) or 25 mmΒ² (aluminum)|Ambient temperature ≀ +30Β°C|The cable is not laid in a bundle with other wires|High-quality terminals are used (no twists)-->

Types of 63A machines: B, C or D - what to choose?

Circuit breakers are divided into classes according to tripping characteristic, which determines at what excess current a shutdown will occur. There are three main types available for the 63A machine:

Type Response range Where is it used?
B 3–5 Γ— In (triggers at 189–315A) Household networks with active load (lighting, heaters)
C 5–10 Γ— In (triggered at 315–630A) Mixed loads (sockets, air conditioners, refrigerators)
D 10–20 Γ— In (triggers at 630–1260A) Powerful motors, welding machines, transformers

Optimal for most household and garage networks type C. It provides a balance between short circuit protection and inrush current resistance. Type B suitable if there is only active load in the network (for example, heaters or lamps), and the type D needed for equipment with high starting currents (for example, compressor ZIL-130 or welding inverter Resanta SAI-220).

Example: if a 63A circuit breaker is connected asynchronous motor 7.5 kW, its starting current can reach 35–40A. Automatic type C will not turn off at startup, but the type B - will work falsely.

πŸ’‘

If you use several powerful tools in your garage or workshop (e.g. lathe and welding machine), it is better to install an automatic type D β€” it will withstand simultaneous startup of equipment without false alarms.

Frequent mistakes when choosing a 63A machine

Even experienced electricians sometimes make mistakes when selecting a circuit breaker. Here are the most common of them:

  • ❌ Ignoring inrush currents: connecting a 5.5 kW motor to a 63A type machine B will lead to false positives at startup.
  • ❌ Cable mismatch: using a 10 mmΒ² wire with a 63A machine is fraught with overheating and fire.
  • ❌ Failure to take temperature into account: in a hot garage (+35Β°C), a 63A circuit breaker can operate already at 55–60A.
  • ❌ Connection "anyhow": poor contact in the terminals of the machine leads to heating and failure.

To avoid problems, follow simple rules:

  1. Always use a cable with a larger cross-section (for example, 25 mmΒ² instead of 16 mmΒ²).
  2. For engines and welding machines, use automatic machines like D.
  3. Check the temperature of the machine after an hour of operation under load - it should not be hot.
⚠️ Attention: If a 63A circuit breaker often trips for no apparent reason, do not rush to install a more powerful one (for example, 80A). First check:
  • πŸ” The state of the contacts in the machine (is there any burning).
  • πŸ” Cross-section and integrity of the cable (is there any overheating or damage).
  • πŸ” Simultaneous operation of several powerful devices (perhaps the total load exceeds the calculated one).

Replacing the machine with a more powerful one without eliminating the cause can lead to a fire!

Practical examples: what can be connected to a 63A circuit breaker?

Let's look at real scenarios for connecting a load to a 63A circuit breaker in a single-phase and three-phase network.

Example 1: Garage with single-phase 220V network

  • πŸ”§ Welding machine Resanta SAI-220 (power 7.5 kW, starting current 35A).
  • πŸ”§ Compressor Fubag 50l (2.2 kW, starting current 12A).
  • πŸ’‘ Lighting (0.5 kW).
  • πŸ”Œ Sockets for tools (1 kW).
Total power: 7.5 + 2.2 + 0.5 + 1 = 11.2 kW - this is close to the limit for a 63A type machine C (recommended load up to 10–11 kW). If the welding machine and the compressor are running at the same time, the machine may work. Solution: distribute the load across different machines or use type D.

Example 2: Private house with a three-phase 380V network

  • 🏠 Electric boiler Protherm Skat 18 kW.
  • πŸ”Œ Three-phase stove Gorenje (7 kW).
  • πŸš— Car charger 3 kW.
Total power: 18 + 7 + 3 = 28 kW β€” fits within the recommended 25–30 kW for a 63A circuit breaker in a 380V network (with cos Ο† = 0.8). However, the boiler and stove may produce inrush currents when starting, so it is better to use an automatic type D or install separate machines on the boiler and stove.
What happens if you connect a 50 kW load to a 63A circuit breaker?

If the power is exceeded, the machine will not turn off immediately - the response time depends on the type (B, C, D) and the magnitude of the excess. For example:

- At a load of 50 kW (β‰ˆ136A on a 380V network), the type C (63A) circuit breaker will turn off in 5–10 seconds.

- A type D machine can last up to 20–30 seconds, but the cable will overheat during this time.

- Consequences: insulation melting, short circuit or fire.

FAQ: Frequently asked questions about the 63A assault rifle

Is it possible to install a 63A machine to enter an apartment?

In most apartments with a single-phase 220V network, a 63A circuit breaker is redundant - the standard allocated power is 7-10 kW, which corresponds to a 32-40A circuit breaker. Installation 63A is only possible if:

  • πŸ“„ The technical specifications (TU) specify a power of β‰₯ 12 kW.
  • πŸ”Œ Input cable cross-section β‰₯ 16 mmΒ² (copper).
  • 🏒 Permission from the management company (in some houses the risers are not designed for such currents).

Without approval, replacing the machine with a more powerful one may result in a fine from the energy supervision authority.

Which machine should I put on an 11 kW (380V) electric motor?

For a three-phase motor 11 kW:

  1. Rated current: I = P / (√3 Γ— U Γ— cos Ο†) = 11000 / (1.73 Γ— 380 Γ— 0.8) β‰ˆ 21A.
  2. Starting current: up to 5–7 Γ— 21A = 105–147A.
  3. Recommended machine: 25A type D (operation range 250–500A).

Automatic 63A type C will also work, but it’s better to choose Dto avoid false positives during startup.

Why does the 63A automatic machine get hot?

Heating of the machine can be caused by:

  • πŸ”₯ Bad contact in the terminals (you need to tighten or strip the wires).
  • πŸ”₯ Overload (for example, a 15 kW load is connected to a 63A circuit breaker on a 220V network).
  • πŸ”₯ Poor-quality machine gun (cheap Chinese models often get hot even at rated current).
  • πŸ”₯ High ambient temperature (in a hot room the machine can operate at a current of 50–55A).

If the heating is strong (you cannot hold your hand), disconnect the load immediately and check the connections!

Is it possible to replace a 63A circuit breaker with an 80A one without replacing the cable?

Absolutely not! The cable cross-section is designed for a maximum current of 63A. Installing an 80A machine will lead to:

  • ⚑ Cable overheating (risk of fire).
  • ⚑ Accelerated wear of insulation.
  • ⚑ Possible refusal of the insurance company in case of fire (since the rules of the PUE are violated).

If you need more power, first replace the cable with a thicker one (for example, from 16 mmΒ² to 25 mmΒ²), and then install an 80A circuit breaker.

How to check if the 63A machine is fake?

To avoid buying a counterfeit machine, pay attention to:

  • 🏷️ Marking: for original machines ABB, Schneider Electric or IEK it is clear, without blurred letters.
  • πŸ” Housing: The plastic should be matte, without burrs or chemical smell.
  • βš–οΈ Weight: counterfeit machines are often lighter than the original ones (e.g. ABB S201 C63 weighs ~200 g).
  • πŸ’° Price: if the machine costs 2-3 times cheaper than the market price, this is a reason to doubt.

It is better to buy machines in trusted stores (for example, ETM, 220pro) and check certificates of conformity.