In the United States, residential service is 120 volts for standard outlets and lighting, and 240 volts for high-power appliances like electric ranges and central air conditioning. The panel safely distributes this dual-voltage power to all branch circuits. The primary rating of an electrical panel is its maximum amperage, which measures the volume of electrical current it can safely distribute. Each circuit powers specific areas or appliances. It contains: Everything that uses electricity in your home — lights, outlets, appliances, HVAC — traces. The amp rating of a main electrical box is typically 100, 125, 150, or 200 amps in modern United States residential properties, though older homes may still operate on 60-amp service.