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What Is the Biggest Size Single-Phase Motor?

Michael Logan

Single-phase current is available to residential electric customers. Appliance and tool motors that operate on a home's electrical system are necessarily single-phase motors for this reason. Single-phase motors are inherently inefficient and therefore limited in horsepower.

Single-Phase Current

Single phase electric motors operate tools and appliances.

Single-phase alternating current rises from a negative voltage to a positive voltage before falling back to a negative voltage again, repeating the cycle 60 times every second. This type of electrical power is commonly supplied to residential and commercial buildings because it is well-suited to light electrical loads for lighting and small to medium appliances and tools.

Single-Phase Motors

Single-phase motors become increasingly inefficient as they grow larger and require higher currents to operate. The limitations of residential electrical power coupled with the inefficiency of single-phase motors makes them impractical for higher power applications. Motor manufacturers make small, single-phase motors for residential and commercial use, and large three-phase motors for industrial use.

Large Single-Phase Motors

The largest single-phase motors suitable for residential use top out at 10 horsepower. A few commercial applications may be found for higher voltage single-phase motors at up to 15 horsepower, but these are rare and require 480 volts of single-phase current to operate. Three-phase motors are much more efficient and manufacturers make them in ratings of hundreds of horsepower.