What type of service is characterized by having two 120V hot legs and a ground?

Single-phase service is characterized by having two 120V hot legs and a ground. In a typical residential single-phase system, the two hot wires each carry 120 volts of electrical potential relative to the neutral or ground. This setup allows for the typical operation of household appliances and lighting, which are designed to operate at 120V.

In contrast, three-phase service consists of three alternating currents that are spaced equally apart in phase angle, providing greater efficiency and a more constant power flow. This type of service is usually used in industrial applications where a substantial amount of power is required. Single-phase service is more common in residential settings, whereas three-phase service is typically employed in commercial or industrial environments.

Thus, the correct answer highlights the characteristics of single-phase service, which operates with two hot legs and a ground, making it suitable for typical household use.