ToolsArmenia Knowledge Base What Electrical Voltage (V) Is and How to Account for It When Choosing Tools and Equipment Voltage is one of the first figures on a tool or equipment rating plate. It shows which supply or battery the device is designed for, and the wrong voltage can damage it or reduce its performance. Reading time: about 7 min Updated: October 2026 ToolsArmenia Editorial Team Contents What voltage isHow to read voltage on the rating plateMains vs battery voltageCommon mistakesFinal checklistFAQ What voltage isElectrical voltage is the potential difference between two points that "pushes" current through a circuit. It is measured in volts (V). Voltage, current (A) and power (W) are linked: for the same power, a higher voltage means a lower current.For mains devices the voltage is set by the supply network; for cordless tools it is set by the battery type. Explanations of other technical terms are in Tool Technical Glossary.Simple explanationVoltage can be compared with water pressure in a pipe, and current with the amount of water flowing. A device must expect exactly the pressure the supply provides. How to read voltage on the rating plate220–240 V and 230 VIn Armenia and the region, household supply is single-phase, nominally 220–230 V, 50 Hz. "220–240 V" means the device is designed to work within that range. This is the most common rating for power tools.380–400 V (three-phase)Powerful machine tools, compressors, welders and electric motors can be designed for a three-phase supply. They cannot be connected directly to a single-phase supply.Permitted voltage fluctuationSupply voltage can fluctuate. A significant drop makes motors lose power and overheat, while overvoltage can damage electronics. In such cases a voltage stabilizer is used.Battery voltageThe voltage of a cordless tool (12, 18, 20, 36 V and so on) indicates the system class. Battery and tool must belong to the same compatible system from the manufacturer; the same voltage alone does not prove compatibility.Voltage drop in long cordsIn a long, thin extension cord the voltage drops and the tool works weakly. The cable cross-section must match the power and the length.WarningDo not connect a device to a supply whose voltage does not match the rating plate, and do not use an incompatible battery or charger even if the voltage is the same. Mains vs battery voltageBelow are common voltage markings and what they mean in practice.Rating plate markingWhere you see itWhat it meansWhat to check220–240 V ~ 50/60 HzCorded power toolsSingle-phase household supplySocket and cord condition230 V ~ 50 HzEquipment, pumpsSingle-phase supply, European markingBreaker rating380–400 V 3~Machine tools, compressorsThree-phase supplyAvailability of a three-phase circuit18 V, 20 V MaxCordless toolsBattery system classBattery compatibility Common mistakesBuying a three-phase device for a single-phase supply.Assuming batteries of the same voltage are interchangeable.Using a long, thin extension cord with a powerful tool.Ignoring strong voltage drops at a country house or building site.Comparing cordless tools by voltage alone without power and capacity.Good practiceIf your supply voltage is unstable, measure it with a multimeter at different times and, if needed, choose a stabilizer of suitable power. Final checklistDevice voltage matches my supplyI know whether the supply is single- or three-phaseThe extension cord cross-section is sufficientThe battery is compatible with the tool according to the manufacturerA stabilizer is planned if the voltage fluctuates Frequently asked questionsCan a 230 V device run on a 220 V supply?Yes, this is usually the same nominal single-phase supply and devices are designed for permitted fluctuations. Check the exact range in the manual.Why does a tool run weakly on a long cord?In a long, thin cable the voltage drops and the motor receives less energy. Use a thicker or shorter cable.Is a higher-voltage cordless tool always more powerful?Not always. Power also depends on the motor, electronics and battery output, so compare the performance stated by the manufacturer as well.What does the "3~" marking mean?It means three-phase alternating current, so the device is designed for a 380–400 V three-phase supply.How can I protect devices from voltage spikes?Use a voltage stabilizer or surge protection devices, and suitable protective breakers in the panel. Read alsowhat is electric current (A)what is frequency (Hz)what is insulation classhow to choose tool power (W) Related categoriesSoldering ToolsAir CompressorsWelding devicesVacuum cleanersWater pumpsPressure washersVoltage stabilizersElectric space heaters and heat blowersCar battery chargers and starter-chargersElectric hoists and winchesElectric concrete mixersDrill pressesMetal cut-off and band sawsThicknessers and jointersTable sawsVertical band sawsWood lathesElectric motorsFansDehumidifiers Next article: what is electric current (A)
