What is the typical frequency of AC power in the United States?

In the United States, the standard frequency of alternating current (AC) power is 60 Hz. This means that the current alternates in direction 60 times per second. The choice of 60 Hz as the frequency has historical roots and is a widely accepted standard for electrical power distribution in North America.

The frequency of 60 Hz is important for the operation of electrical devices and appliances, as they are designed to work efficiently at this frequency. Operating devices at the correct frequency ensures optimal performance and reduces the risk of damage. For example, electric motors and transformers are designed to operate efficiently at this frequency, and any significant deviation from it can lead to inefficiencies, overheating, or failure.

In contrast, other frequencies, such as 50 Hz, are used in many other parts of the world, particularly in Europe and some other regions. The values of 70 Hz and 75 Hz are not standard frequencies used in power systems and are largely irrelevant in practical applications for residential or commercial power supplies. Thus, the established frequency of 60 Hz in the U.S. plays a critical role in aligning with global practices and ensuring reliable and safe electrical supply throughout the country.