When it comes to wiring a car, garage or home workshop, choosing the right circuit breaker becomes critical. Automatic on 32 amps is one of the most popular solutions for protecting medium-power circuits, but how do you know how many kilowatts it can withstand? The answer depends on several key factors: line voltage (220V or 380V), type of connected load (reactive or reactive) and even ambient temperature.

Many car owners and craftsmen are faced with a dilemma: is it possible to connect a welding machine, compressor or powerful heater through such an automatic machine? Errors in calculations can result not only in tripping the protection, but also in overheating of the wiring, short circuits, or even fire. In this article we will look at exact calculation formulas, we will present ready-made power tables for different voltages, and also talk about the nuances that even experienced electricians often overlook.

Why is it important to know the power of the machine in kilowatts?

Circuit breaker on 32A is not just a β€œswitch”, but a device that protects your electrical network from overloads and short circuits. But why is it so important to convert amps to kilowatts?

The point is that all household and industrial appliances are labeled by power consumption (W or kW), not by current. For example, on a welding machine it is indicated 5 kW, and on the compressor - 2.2 kW. If you don't know how many kilowatts your machine can handle, you risk:

  • πŸ”Œ Connect too powerful equipment, which will lead to constant shutdowns.
  • πŸ”₯ Reload wiring, if the machine is selected with a reserve, but the cable is not.
  • ⚑ Burn sensitive electronics (for example, in modern car chargers) if the machine does not work on time.

In addition, car workshops and garages often use three-phase networks (380V), where the power calculation differs from the usual household 220V. A mistake in choosing a machine here can result in even more serious consequences.

πŸ“Š What is the voltage in your garage or workshop?
220V (single-phase)
380V (three-phase)
I don't know
Other

Formula for calculating power for a 32A machine

To find out how many kilowatts the machine can withstand 32 amps, you need to use Ohm's law and the power formula. The basic formula looks like this:

P = U × I × cosφ

Where:

  • P β€” power in watts (W),
  • U - voltage in volts (V),
  • I - current strength in amperes (A),
  • cosΟ† β€” power factor (for active load equals 1).

For most household appliances and lighting systems cosΟ† β‰ˆ 1, so the formula simplifies to:

P = U Γ— I

However for inductive load (electric motors, transformers, welding machines) cosΟ† may be significantly lower - for example, 0.7–0.8. This means that the actual power will be less than the calculated one.

πŸ’‘

If you connect an asynchronous motor through a 32A circuit breaker (for example, in a compressor), multiply the result by 0.7–0.8 for an accurate calculation.

How many kilowatts can a 32A 220V machine withstand?

For a single-phase network (220V) the calculation is extremely simple:

P = 220V Γ— 32A Γ— 1 = 7040 W = 7.04 kW

This means that the machine is 32A online 220V able to withstand loads up to 7 kW (with a small margin). However, there are several important nuances here:

  • πŸ”Ή Long-term load: The machine can withstand high power for a short time (for example, during starting currents), but with a long-term load close to 7 kW it will heat up and may work.
  • πŸ”Ή Ambient temperature: In a hot garage or workshop, the rated current of the machine is reduced by 10–15%. That is, the real limit may not be 7 kW, but about 6–6.5 kW.
  • πŸ”Ή Machine quality: Cheap Chinese machines often do not correspond to the declared characteristics and can operate at 25–28A instead of 32A.

Load examples for 220V:

Device Power (kW) Is it possible to connect via 32A?
Welding machine REDMBO (household) 5.5 Yes
Compressor Fubag 2.2 Yes (with reserve)
Electric boiler Protherm 8.0 No (exceeds limit)
Car wash Karcher 3.0 Yes

How many kilowatts can a 32A at 380V machine withstand?

For a three-phase network (380V) power calculation is different since the load is distributed over three phases. Formula for a three-phase network:

P = √3 Γ— U Γ— I Γ— cosΟ†

Where √3 β‰ˆ 1.73. Substitute the values:

P = 1.73 Γ— 380V Γ— 32A Γ— 1 = 20,556 W β‰ˆ 20.6 kW

However this total power for all three phases. Each phase includes:

Pphase = 20.6 kW / 3 β‰ˆ 6.87 kW

It is important to understand that:

  • πŸ”§ Unsymmetrical load: If one phase is loaded more heavily than others (for example, a powerful machine is connected), the machine can operate even with a total power of less than 20 kW.
  • πŸ”Œ Machine type: For three-phase networks use three-pole or four-pole machine guns. The latter also disconnect the neutral, which is important for protecting sensitive equipment.

Load examples for 380V:

Equipment Power (kW) Is it possible to connect via 32A?
Lathe Corvet 15.0 Yes (with reserve)
Industrial compressor ABAC 18.5 Yes (close to the limit)
Welding station ESAB 22.0 No (exceeds limit)
Ventilation system 5.0 Yes (with a large margin)
What happens if you exceed the power by 380V?

If the power in a three-phase network is exceeded, the thermal protection of the machine will first work (after 10–30 minutes), and if there is a short circuit, the electromagnetic release will work (instantly). However, if the load is asymmetrical, one of the phases may burn out, which will lead to failure of equipment with three-phase motors (for example, machines or pumps).

What cable is needed for a 32A machine?

The machine protects not only the equipment, but also wiring. If you install a machine at 32A, but the cable is not designed for such a current, the wires will heat up, which will lead to melting of the insulation and a short circuit.

To select a cable, use the table of permissible current loads:

Cable cross-section (mmΒ²) Max. current for copper (A) Max. current for aluminum (A) Suitable for 32A?
4 28 21 No (only for copper with reserve)
6 38 30 Yes (optimal for copper)
10 50 39 Yes (with a large margin)

Recommendations for choosing a cable:

  • ⚑ For copper: Optimal section - 6 mmΒ² (withstands up to 38A).
  • ⚑ For aluminum: Minimum section - 10 mmΒ² (withstands up to 39A).
  • ⚑ For garage/workshop: Better to use copper cable VVGng-LS 6 mmΒ² β€” it does not support combustion and is resistant to mechanical damage.

The cable cross-section corresponds to the current (6 mmΒ² for copper)|

The cable has no damage to its insulation|

Connections are made via terminal blocks or soldering|

The cable is laid in a corrugation or cable channel (to protect against rodents in the garage) -->

Frequent mistakes when choosing a 32A machine

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

⚠️ Attention: Installing a circuit breaker with an overrated rating (for example, 40A instead of 32A) will not increase the power of the network, but may lead to a fire in the wiring if the cable is not designed for such current.
  • πŸ”˜ Ignoring cosΟ†: Many people forget that for reactive loads (motors, transformers) the power factor must be taken into account. For example, a welding machine with declared 7 kW at cosΟ† = 0.7 will actually consume 10 kW, which will exceed the capabilities of the 32A machine in a 220V network.
  • πŸ”˜ Unbalanced load at 380V: Connecting powerful equipment to only one phase of a three-phase network can cause phase imbalance and tripping of the circuit breaker even with a total power of less than 20 kW.
  • πŸ”˜ Saving on quality: Cheap machines (for example, IEK or EKF budget series) may have underestimated real characteristics. For critical circuits it is better to choose ABB, Schneider Electric or Legrand.

Another common mistake is incorrect choice of machine type. Different characteristics are suitable for different tasks:

  • πŸ”Ή Type B: For lighting circuits and sockets in residential premises (trips at 3-5 times the current).
  • πŸ”Ή Type C: For garages and workshops (triggered at 5–10 times the excess). Suitable for most cases with 32A.
  • πŸ”Ή Type D: For equipment with high starting currents (for example, powerful compressors or machine tools).

Practical connection examples

Let's look at several real scenarios that car owners and mechanics face.

Example 1: Garage with single-phase 220V network

Do you want to connect:

  • Welding machine Resanta SAI-220 β€” 5.5 kW,
  • Compressor Fubag VC/50L β€” 2.2 kW,
  • Lighting - 0.5 kW.

Total power: 5.5 + 2.2 + 0.5 = 8.2 kW.

Automatic 32A (7 kW) doesn't fit β€” you need either separate wiring with two machines (for example, 25A for welding and 16A for the rest), or a 40A machine with a 10 mmΒ² cable.

Example 2: Car service with a three-phase 380V network

Equipment:

  • Lift - 4 kW,
  • Lathe - 7 kW,
  • Ventilation - 2 kW.

Total power: 4 + 7 + 2 = 13 kW.

Automatic 32A (20.6 kW) fits, but you need to make sure that the load is distributed evenly across the phases. For example:

  • Phase 1: Hoist (4 kW),
  • Phase 2: Machine (7 kW),
  • Phase 3: Ventilation (2 kW).

Here phase 2 is loaded more heavily, but this is acceptable, since 7 kW < 6.87 kW (limit per phase). However, it is better to redistribute the load or use a 40A machine.

Example 3: Electric vehicle charging station

If you are installing a charger for Tesla or other electric vehicle, please note:

  • πŸ”‹ Charging power: For example, Wallbox at 22 kW requires a three-phase connection.
  • ⚑ Automatic: 32A (20.6 kW) doesn't fit β€” you need a separate line with a 32A circuit breaker and cable 10 mmΒ², but better 50A with cable 16 mmΒ².
πŸ’‘

For powerful equipment (over 15 kW), always use a separate line with a breaker and cable designed with a margin of 20–30%.

FAQ: Frequently asked questions about the 32A machine gun

Is it possible to put a 32A machine on an outlet in the garage?

It is possible, but only if the outlet is designed for a current of 32A (usually these are special power outlets for stoves or equipment). Standard 16A household sockets are not suitable - they will melt under such a load.

Why does the 32A automatic machine operate at a load of 5 kW?

Probable reasons:

  • The machine is faulty (especially if it is a cheap model).
  • Poor contact in the terminals - the thermal protection heats up and falsely triggers.
  • The load is reactive (for example, a cheap welding machine), and the real power is higher.

Check the contacts and replace the machine with a quality one (for example, ABB S200).

Which machine should be put into the garage if there is 380V and 15 kW equipment?

For input, it is better to use a 25A machine (type C or D), since:

  • 15 kW < 20.6 kW (limit for 32A), but the input circuit breaker must be one step higher than the group ones.
  • If you put 32A on the input, then if there is an overload, it may not work on time, and the group circuit breakers will burn out.
Is it possible to connect an inverter welding machine via a 32A machine?

Yes, but with reservations:

  • For 220V: only if the device power does not exceed 5–6 kW (taking into account cosΟ†).
  • For 380V: you can connect devices up to 18–19 kW, but with an even distribution across phases.

Check in the device passport maximum input current - it should not exceed 32A.

What is the difference between a 32A type C and type D machine?

The main difference is in frequency of operation of the electromagnetic release:

  • Type C: Triggers at 5-10 times the current (that is, at 160-320A). Suitable for most household and garage chains.
  • Type D: Triggers at 10–20 times excess (320–640A). Needed for equipment with high starting currents (for example, powerful compressors or machine tools).