The main electrical panel, commonly called the breaker box, is the central distribution point for all power inside the home. The main service disconnect feeds the panel's two main bus bars, which carry the two 120-volt “hot” legs of power. Standard household circuits operate at 120 volts by drawing. A distribution board (also known as panelboard, circuit breaker panel, breaker panel, circuit breaker, electric panel, fuse box or DB box) is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits while providing a protective fuse or circuit. The National Electrical Code (NEC) provides comprehensive safety standards for electrical installations, including requirements for electrical panels (main service panels and subpanels or breaker box). NEC Article 408 covers switchboards, switchgear, and Panelboards installation and applications. This voltage is stepped down through transformers (usually mounted on poles) to a level suitable for residential use. Let's make an example for clarity: A newly constructed residential area introduces a 10kV power line to a substation. 4kV), power is distributed to a main distribution panel.
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