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This standard established 120 volt nominal system and two ranges for service voltage and utilization voltage variations. [18] Today, virtually all American homes and businesses have access to 120 and 240 V at 60 Hz. Both voltages are available on the three wires (two "hot" legs of opposite phase and one "neutral" leg).
120 V circuits are the most common, and used to power NEMA 1 and NEMA 5 outlets, and most residential and light commercial direct-wired lighting circuits. 240 V circuits are used for high-demand applications, such as air conditioners , space heaters , electric stoves , electric clothes dryers , water heaters , and electric vehicle charge points .
Most of the Americas use 60 Hz AC, the 120/240 volt split-phase system domestically and three phase for larger installations. North American transformers usually power homes at 240 volts, similar to Europe's 230 volts. It is the split-phase that allows use of 120 volts in the home. Japan's utility frequencies are 50 Hz and 60 Hz.
Three-phase transformer with four-wire output for 208Y/120 volt service: one wire for neutral, others for A, B and C phases. Three-phase electric power (abbreviated 3ϕ [1]) is a common type of alternating current (AC) used in electricity generation, transmission, and distribution. [2]
A simple voltage dropper can be used to reduce the voltage for low-power devices; if more than 12V is required, or for high-powered devices, a switched-mode power supply is used. The output will usually be DC in the range 1.5–24 V. Power supplies that output either 100–120 V AC or 210–240 V AC are available; they are called inverters ...
These two give different voltages from a given supply. For example, on a 120/208 three-phase system, which is common in North America, the phase-to-neutral voltage is 120 volts and the phase-to-phase voltage is 208 volts. This allows single-phase lighting to be connected phase-to-neutral.
Frequency and voltage supplied to most premises by country. Mains electricity by country includes a list of countries and territories, with the plugs, voltages and frequencies they commonly use for providing electrical power to low voltage appliances, equipment, and lighting typically found in homes and offices.
Aside from obviating the need for internal power supplies, adapters offer flexibility: a device can draw power from 120 VAC or 230 VAC mains, vehicle battery, or aircraft battery, just by using different adapters. Safety can be another advantage, as hazardous 120 or 240 volt mains power is transformed to a lower, safer voltage at the wall ...