Circuit breakers on 63 amps - one of the most popular in car garages, workshops and home electrical panels, where powerful consumers are connected: welding machines, compressors, charging stations for electric vehicles or inverter power supplies. But how do you know how much kilowatt can such a machine withstand? The answer depends on the type of network (single-phase 220V or three-phase 380V), equipment power factor and even ambient temperature.

Many car owners mistakenly believe that 63A = 63 kW, but this is a gross mistake that can lead to overheating of the wiring or tripping of the protection at the most inopportune moment. In this article we will figure out how to correctly calculate the power for a machine. C63, B63 or D63, we will present ready-made tables for different voltages and tell you what nuances are important to consider when choosing protection for a garage or workshop.

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Why can't you just multiply 63A by 220V?

At first glance, the power formula P = U ร— I (where P - power in watts, U - tension, I - current) seems simple. But in real conditions everything is more complicated:

1. Power factor (cos ฯ†). Most electrical appliances (especially those with motors, transformers or switching power supplies) have a reactive component. For example, a welding machine or compressor may have cos ฯ† = 0.7โ€“0.85, which reduces actual power by 15โ€“30%.

2. Network type. In a three-phase network 380V calculation is carried out taking into account root of three (โ‰ˆ1.73), since the voltage between phases is higher than between phase and zero.

3. Temperature conditions. Automatic on 63A at +40ยฐC in a garage it can work already at 55A, and at -10ยฐC - skip 68A without shutting down. This is due to the thermal characteristics of the bimetallic strip.

4. Triggering characteristics. Type machines B, C or D have different response thresholds:

  • ๐Ÿ”Œ B63 - will work when 3โ€“5 times the current (189โ€“315A). Suitable for lighting networks.
  • โšก C63 - will work at 5โ€“10 times excess (315โ€“630A). A universal option for garages.
  • โš™๏ธ D63 - will work at 10โ€“20 times the excess (630โ€“1260A). Used for starting currents (for example, diesel generator starters).
๐Ÿ“Š Which machine is in your garage?
At 16A
At 25A
At 40A
At 63A
I don't know

Formulas for calculating power for a 63A machine

To determine exactly how much kilowatt will withstand the machine, use these formulas:

1. Single-phase network (220V)

For household appliances and most garage tools:

P = U ร— I ร— cos ฯ†

where:


P - power (W),


U = 220V,


I = 63A,


cos ฯ† โ€” power factor (taken from the device passport).

Example: for a compressor with cos ฯ† = 0.8:

P = 220 ร— 63 ร— 0.8 = 11,088 W โ‰ˆ 11.1 kW

2. Three-phase network (380V)

For welding machines, machines or charging stations:

P = โˆš3 ร— U ร— I ร— cos ฯ†

where:


โˆš3 โ‰ˆ 1.73,


U = 380V (line voltage),


I = 63A.

Example: for a three-phase pump with cos ฯ† = 0.85:

P = 1.73 ร— 380 ร— 63 ร— 0.85 โ‰ˆ 34,500 W โ‰ˆ 34.5 kW
๐Ÿ’ก

If the device passport indicates power in kVA (kilovolt-amperes), multiply it by cos ฯ†to get real kilowatts. For example, 20 kVA ร— 0.8 = 16 kW.

Power table for 63A machine

For convenience, we have collected ready-made power values taking into account different coefficients cos ฯ† and network types:

Network type cos ฯ† Power (kW) Equipment examples
Single phase (220V) 1.0 13.86 Heaters, incandescent lamps
Single phase (220V) 0.8 11.09 Compressors, pumps
Three-phase (380V) 0.85 34.5 Welding machines, machines
Three-phase (380V) 0.7 28.4 Motors with high starting currents

โš ๏ธ Attention: If you connect nonlinear load (for example, an inverter welding machine or an electric vehicle charger), the actual power may be 10โ€“20% lower due to current distortion.

What cable is needed for a 63A machine?

The machine protects not only the equipment, but also the wiring. If the cable cross-section is insufficient, it will overheat before the machine operates. For 63A recommended:

  • ๐Ÿ”Œ Copper cable: minimum 10 mmยฒ (for open installation) or 16 mmยฒ (for hidden).
  • ๐Ÿ”Œ Aluminum cable: minimum 16 mmยฒ (open) or 25 mmยฒ (hidden).

Example: to connect a welding machine to 34 kW in the garage you will need:

  • Automatic C63 (three-phase).
  • Cable VVGng 5ร—10 (5 cores of 10 mmยฒ each).
  • Terminal connections on 120A (with a reserve).

Make sure that the machine corresponds to the type of load (C for garages)|Check the cable cross-section according to the table above|Measure the voltage in the network (must be at least 200V for 220V and 360V for 380V)|Check the tightness of the terminals (weak contact = heating)-->

Frequent mistakes when choosing a 63A machine

Even experienced car enthusiasts make mistakes that lead to accidents. Here are the most common:

  1. Ignoring inrush currents. For example, a compressor motor may draw 3 to 5 times more current when starting than when running. Automatic B63 may work falsely, but D63 - will not operate in the event of a short circuit.
  2. Connecting a single-phase load to a three-phase circuit breaker. If you use only one phase from a three-phase machine C63, the maximum power will not be 34.5 kW, but only 11.1 kW (with cos ฯ† = 0.8).
  3. Save on cable. Cable 6 mmยฒ cheaper, but at a current of 60A it will heat up, which will lead to a fire. Always take the section with a margin.

โš ๏ธ Attention: If your garage has old aluminum wiring, 63A absolutely cannot be set - maximum current for aluminum 4 mmยฒ is only 28A (according to PUE 7.1.34).

What happens if you install a 63A machine on weak wiring?

If the permissible current is exceeded, the cable will begin to melt long before the machine operates. For example, cable 2.5 mmยฒ at a current of 60A it will overheat to 90ยฐC in 10โ€“15 minutes, which will lead to destruction of insulation and a short circuit. The machine will work, but a fire may already have started.

Practical examples for car owners

Let's look at real scenarios that garage and workshop owners face:

1. Connecting the welding machine

Let's say you have devices Resanta SAI-220 (power 7.5 kW, cos ฯ† = 0.7) and Kedr MMA-200 (5.5 kW, cos ฯ† = 0.8). Is it possible to connect them through one machine? C63?

Calculation:

  • Resanta: 7500 W / 0.7 โ‰ˆ 10,714 VA.
  • Cedar: 5500 W / 0.8 โ‰ˆ 6,875 VA.
  • Total: 10,714 + 6,875 = 17,589 VA โ‰ˆ 17.6 kVA.

For a single-phase network: 17,600 VA / 220V โ‰ˆ 80A - this is more than 63A. Conclusion: need a machine gun 80A or separate connection.

2. Electric vehicle charging station

Station Tesla Wall Connector (11 kW, cos ฯ† = 0.95) is connected to a three-phase network. Is an automatic machine suitable? C63?

Calculation: 11,000 W / (1.73 ร— 380V ร— 0.95) โ‰ˆ 17.5A. Automatic on 63A has a large margin, but it is important to check the cable cross-section (minimum 6 mmยฒ for copper).

3. Compressor and lighting in the garage

Compressor Fubag VCF/50 (2.2 kW, cos ฯ† = 0.8) + 10 lamps of 100W each. Total power: 2200 / 0.8 + 1000 = 3650 W โ‰ˆ 16.6A. A machine gun is enough here C25, and 63A will be redundant.

๐Ÿ’ก

For most garage needs (lighting, sockets, compressor up to 3 kW), a 25โ€“40A machine will suffice. 63A is justified only for powerful equipment or three-phase networks.

FAQ: Answers to frequently asked questions

Is it possible to put a 63A machine at the entrance to the garage if there are only sockets and lights there?

No, this is redundant and dangerous. For a long-term garage with lighting (1 kW) and sockets (3โ€“5 kW), the machine will be enough to 25โ€“40A. Automatic 63A will not protect the wiring from overload if the cable cross-section is designed for a lower current. For example, cable 4 mmยฒ withstands maximum 38A (according to the PUE), and the automatic 63A will pass more current, which will lead to a fire.

What is the difference between the B63, C63 and D63 assault rifles?

The main difference is operation frequency when the rated current is exceeded:

  • B63: will work at 3โ€“5 times excess (189โ€“315A). Suitable for lighting networks without inrush currents.
  • C63: will work at 5โ€“10 times excess (315โ€“630A). A universal option for garages with compressors or pumps.
  • D63: will work at 10โ€“20 times excess (630โ€“1260A). Used for equipment with high starting currents (for example, diesel generators).

For a car garage they usually choose C63.

How many kilowatts will a 63A circuit breaker withstand in a 12V network (car network)?

In low-voltage networks (12V, 24V) the current is much higher for the same power. The formula is the same: P = U ร— I.

Example: for network 12V:

P = 12V ร— 63A = 756 W (0.756 kW).

This means that the machine 63A in the vehicle's on-board network protects a load with a power of no more than 756 W (for example, two powerful LED spotlights).

Is it possible to use a 63A circuit breaker to connect your home to the network?

Yes, but only if:

  1. Your home is connected to a three-phase network 380V.
  2. The total power of all devices does not exceed 30โ€“35 kW (taking into account cos ฯ†).
  3. Input cable cross-section not less than 16 mmยฒ (copper) or 25 mmยฒ (aluminium).

For single-phase connection 220V automatic 63A excessive - the maximum permitted power for private houses is usually limited 15 kW (automatic 50A).

Why does the 63A circuit breaker heat up if the load is only 10 kW?

The reasons may be as follows:

  • ๐Ÿ”ฅ Poor contact in the terminals of the machine (you need to tighten or strip the wires).
  • ๐Ÿ”ฅ Phase imbalance in a three-phase network (one phase is overloaded).
  • ๐Ÿ”ฅ Low quality machine (cheap Chinese models can heat up even at rated current).
  • ๐Ÿ”ฅ High ambient temperature (in the garage in summer it can be +40ยฐC, which reduces the permissible current by 20%).

Solution: check the tightness of the terminals, measure the current with clamps on each phase and replace the machine with a trusted manufacturer (ABB, Schneider Electric, Legrand).