What 120V usually means
Many one- and two-person infrared cabins operate on 120V, often at 15A. They can be easier to place, but the manual may still require a dedicated circuit. Larger 120V models may require 20A.
What 240V usually means
Traditional electric heaters and higher-output cabins commonly use 240V. Expect a dedicated double-pole circuit and professional installation. The heater manual, not a generic chart, determines breaker, wire, controls, and connection method.
Do not compare heat by voltage alone
A well-sized 120V infrared cabin and a 240V traditional sauna create different experiences. Compare heater wattage, cabin volume, target temperature, warm-up behavior, radiant coverage, and installation cost rather than treating 240V as automatically better.
Sources and documentation
Specifications, claims, and installation requirements can change. Confirm the current manufacturer manual for the exact model and variant.