in a three phase system each cable caries alternating current and the cables are all shifted in relation to one another by 1/3

Phases refer to different power lines that all carry alternating current. A home electrical system can be either single-phase or three-phase. These phases are separate power lines, each delivering alternating current. In a three-phase system, the sinusoidal voltage of each phase is slightly offset from the others. In the Dutch power grid, all cables running from high-voltage transmission, through medium voltage, and down to low voltage in residential areas are three-phase.

Did you ever notice that almost all power cables through the air come in threes? That's because each cable carries one of three phases

Some homes are connected to all three phases. This is especially common in newer buildings. Three-phase power is sometimes referred to as "high-power current" (krachtstroom in Dutch) because the combined capacity of the three phases is greater, making it more powerful. Certain high-power appliances, such as induction cooktops, often operate on three-phase power.

In other homes, only one of the three phases is connected. If this is the case, the main fuse is usually rated for a higher current. For example, instead of a 3 x 25-ampere fuse found in a three-phase setup, a single-phase connection typically has a 1 x 40-ampere main fuse. This ensures that a single phase can still provide enough power for all household appliances.

Left is how they used to do it: each house in a street is linked to one of the three available phases. On the right the way they do it these days: each house gets all three phases linked to the distribution board

The size of your main connection affects the fixed costs you pay to your grid operator. Generally, the heavier the connection, the higher the annual fixed fee. However, the difference in fixed costs between a 1 x 40A and a 3 x 25A connection is usually minimal. Your grid operator can provide detailed pricing information.

Switching from Single-Phase to Three-Phase

In some cases, upgrading from a single-phase to a three-phase connection may be worth considering. This can be beneficial if you expect to use more electricity—for example, if you plan to install an electric vehicle charging station.

Grid operators typically charge a one-time fee for switching from single-phase to three-phase power. You can find these costs on your grid operator’s website.

Solar inverters also come in single-phase and three-phase models. It’s important to know that a three-phase inverter can only be installed in homes with a three-phase electrical connection. However, a single-phase inverter can be installed in both single-phase and three-phase homes.