Bus Bar
The rigid metal bars inside a panel that distribute power to the breakers. Breakers snap onto the energized bus; damaged or corroded bus bars often mean the panel is done.
Two hot bus bars run down the middle of the panel, fed by the main breaker; each breaker clamps onto one (120V circuits) or both (240V circuits). Separate neutral and ground bars collect the white and bare wires. The bus is the one part of a panel that cannot be cheaply repaired: overheated breaker connections scorch the bus, corrosion pits it, and a loose breaker arcing on the bus is the source of many "buzzing panel" calls.
Bus damage is also why bargain fixes backfire: a new breaker snapped onto a burned bus stub will overheat exactly like the old one. Once a bus shows heat damage, replacement of the panel is the honest recommendation.
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- Main Breaker : The single large breaker at the top of your panel that can disconnect the entire house, and whose rating (100, 150, 200 amps) defines your service size.
- Subpanel : A secondary breaker panel fed from the main panel, used to add circuit capacity or put breakers closer to where the power is used: garages, shops, additions, ADUs.
- Double-Pole Breaker : A breaker occupying two panel spaces that connects across both hot bus bars to deliver 240 volts, used for dryers, ranges, AC units, EV chargers and other heavy loads.
- Tandem Breaker : A slim breaker that fits two separate 120-volt circuits into a single panel space, used to open up room in a full panel where the panel is rated to accept them.