It is often the first question when buying a piston compressor: 230 volts or 400 volts? The answer is not a matter of preference. It depends on two things: the power you need, and the electricity available in your workshop. A wrong choice is costly: a compressor that trips the breaker every time it starts, or a machine you simply cannot plug in.
230 V and 400 V: what are we talking about?
Some people still say "220 V" and "380 V" out of habit. The official values today are 230 V and 400 V, but these are the same installations.
- 230 V single-phase: this is the current from standard sockets, the one found in homes and most small premises. It comes in on two wires (phase and neutral), plus earth.
- 400 V three-phase: this is the current used in industry and in well-equipped workshops. It comes in on three phases (plus neutral and earth) and powers larger motors with less current on each wire.
A machine designed for three-phase cannot be plugged into a single-phase socket, and the reverse is not possible either. The choice is therefore made at the time of purchase.
The simple rule: power decides
| Motor power | Usual power supply | Typical use |
|---|---|---|
| Up to about 2.2 kW (3 hp) | 230 V single-phase, on a socket or a dedicated circuit | Advanced DIY, small workshop, tyre inflation, blow gun |
| 3 to 4 kW | Depending on the model: single-phase possible on a properly sized dedicated circuit, three-phase recommended | Garage, tradesperson using several tools |
| 4 kW and above | 400 V three-phase in the vast majority of cases | Equipped garage, body shop, production workshop |
Beyond a few kilowatts, a single-phase motor draws a very high current, especially at start-up. Three-phase spreads this current over three wires: the motor starts more firmly, runs cooler and lasts longer. This is why professional compressors of 4 kW and above are almost always three-phase.
Advantages and limits of each option
230 V single-phase
- Advantages: can be plugged in almost anywhere, no electrical work needed for low power ratings, practical for a workshop that moves or for a job site.
- Limits: capped power, high inrush current at start-up, breaker that trips if the circuit is too weak or shared with other machines, extension leads to be avoided.
400 V three-phase
- Advantages: high power ratings, gentler start-ups for the installation, less strain on the motor, better endurance in intensive use.
- Limits: the premises need a three-phase supply. If you do not have one, you have to request it from the grid operator or your electricity supplier and bring in an electrician, which takes time and money.
How do you know if your workshop has three-phase?
- Look at the electrical panel: a 4-pole main breaker (three phases plus neutral) indicates a three-phase supply.
- Look for industrial sockets: three-phase sockets are larger, often red (CEE industrial type), with 4 or 5 pins.
- Check your electricity contract or meter: the type of connection (single-phase or three-phase) is stated there.
- If in doubt, ask an electrician: they will also check the available power, which matters as much as the type of current.
What you need to connect your compressor properly
- A dedicated circuit from the panel, with no other heavy load on it.
- A cable cross-section suited to the power and the length. A cable that is too thin heats up and causes the voltage to drop at start-up.
- Protection suited to motors: a breaker sized for the start-up inrush current, and residual current protection.
- No coiled extension lead and no power strip: they are the leading cause of hard starts and overheating motors.
- The direction of rotation, on three-phase: at commissioning, check that the motor turns the right way (an arrow on the machine shows it). If it turns backwards, the electrician swaps two phases.
A professional compressor must be connected, or the connection checked, by a qualified electrician, in accordance with the applicable regulations.
What if I only have 230 V but need power?
There are three solutions:
- Upgrade the premises to three-phase: this is the lasting solution if the workshop is going to grow.
- Choose the most powerful single-phase compressor and a larger tank: the tank acts as a reserve and absorbs consumption peaks, so the compressor starts less often.
- Use a single-phase to three-phase converter or drive: possible in some cases, but to be studied with an electrician, as not all motors and power ratings are suitable.
To estimate the power and tank size you really need, use the configurator and the air receiver size calculator. For running costs, the electricity cost calculator gives a ballpark figure based on your operating hours.
Piston or screw: the other question
If your workshop uses air several hours a day, the question may not just be 230 or 400 V, but piston or screw. Screw compressors, designed to run continuously, are three-phase. Our article Piston vs screw compressor: what is the difference? will help you decide.
What about AIRSTAHL compressors?
The supply voltage of each AIRSTAHL piston compressor is stated on its technical data sheet. Before ordering, check that it matches your installation. If in doubt, send us a photo of your electrical panel or your sockets with your quote request: we will tell you which model is right for you.