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The two types of electrical currents: AC and DC*

Electricity can flow in two main forms: direct current (DC) and alternating current (AC). Each has its own characteristics, specific areas of use, and levels of danger to be aware of.

Direct current (DC)

Direct current — Direct Current or DC — always flows in the same direction. Its voltage remains almost constant over time.

This is the type of current found:

  • in batteries and cells (phones, laptops, electric cars);

  • in solar panels;

  • at the output of AC/DC converters (adapters, power supplies for electronic devices).

Direct current is often used for sensitive electronic devices because it provides stable voltage.

Example: a laptop typically operates at 19 V DC.

Danger: although DC voltages are often lower than mains voltages, high-intensity direct current can cause severe burns or electrocution. Moreover, DC tends to "lock" muscles, making it harder to release a live conductor.

Alternating current (AC)

Alternating current — Alternating Current or AC — periodically changes direction. The voltage varies sinusoidally, oscillating between a positive and a negative value.

This is the type of current supplied by the electrical grid.

  • In homes, the single-phase mains current is 230 V AC (in Europe).

  • In industry or for high power, three-phase (3 phases offset by 120°) is often used, allowing more powerful motors or machines to be powered.

Alternating current is preferred for electricity distribution because it is easier to transform (voltage change via transformers) and transport over long distances with fewer losses.

Danger: alternating current can be very dangerous. From 30 mA (milliamperes), it can already cause cardiac fibrillation. The risk depends on the voltage, frequency, and contact time.

In summary

Type of currentFull nameDirection of currentExample sourceMain useMain danger
DCDirect currentUnidirectionalBattery, solar panelElectronic devices, electric vehiclesBurns, continuous muscle contractions
ACAlternating currentPeriodically changes directionElectrical grid (230 V single-phase, 400 V three-phase)Energy distribution and transportRisk of cardiac fibrillation


*: The technical information presented in this article is provided for guidance only. It does not replace the official notices of the manufacturers. Before any installation, handling or use, please consult the product documentation and follow the safety instructions. Torque.works cannot be held responsible for inappropriate use or incorrect interpretation of the information provided.