99.99% of residential customers and small commercial customers are which type of phase customers?

• A. Three Phase Customers
• B. Three Phase Service
• C. Two Phase Customers
• D. Single Phase Customers

Answer: (D)

Single-phase service is what residential customers typically use. In the U.S., homes are usually fed with a split-phase 120/240-volt system: two 120-volt legs share a common neutral, giving 120 V for standard outlets and 240 V for heavier appliances. This setup is simple, cost-effective, and adequate for lighting, electronics, and everyday appliances, which is why the vast majority of homes—and many small commercial locations—run on single-phase. Three-phase service, by contrast, is reserved for larger loads and equipment that benefit from the smoother power and efficiency of three phases, such as many motors and commercial systems.