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Electrical: Understanding Circuit Breaker Panels

Most homes built in the past fifty years have their electrical circuit lines routed through a circuit breaker panel, a metal box containing as few as 10 or as many as 40 or more circuit breakers that provide protection against electrical overloads. For those with little or no knowledge of electricity, they often seem like complex and dangerous conglomerations of wires and switches sure to electrocute those who dare to come too close.

Electrical panel with cover installedIf you know the location of your breaker panel, frequently the garage, basement, or utility room, go to the panel and take a look. The panel should have a door that may have a latch to keep it shut. Open the door and look inside. Most homes will have a panel similar to the one in the photo, and may have a list showing which breaker controls which circuit in your home. The circuit breakers look like switches, and are, in fact, a type of switch that is designed to detect overloads in the circuit they control and to trip to the off position when necessary.

Circuit breaker panel showing wiringSome circuit breaker panels also contain a large breaker, usually at the top, that controls all the electricity entering the home. They are usually 100A, 150A, or 200A. If the main breaker is not located in the breaker panel it should be found outside in a separate panel adjacent to the electrical power meter. In large homes, or when significant additions have been made to the home, there may be more than one electrical panel, and sometimes there are “sub-panels” that are fed from the main, but contain the circuit breakers for one or more circuits.

The circuit breakers for the standard receptacle and lighting circuits will be single pole, and will normally be 15A or 20A. Large double pole breakers will control appliances such as ranges, water heaters, air conditioners, clothes dryers, or heating systems. They usually range in size from 20A to 60A and normally take up the space of two standard circuit breakers. However, in an effort to allow for the addition of more circuits, manufacturers in recent years developed half-sized breakers that can effectively double the potential capacity. These are especially helpful when you want to add a circuit to an electrical panel where all the spaces are filled. However, it’s important not to overload your electrical panel, and if you have questions on its capacity, it’s best to consult a licensed electrician.

Tripped circuit breakers are sometimes difficult to locate, as they do not go to the full off position, but to a mid position. To reset a tripped breaker you should first turn it off and then back to the on position. Any breaker that immediately trips after being reset indicates either an overload or a short-circuit. It’s possible, but unlikely, that such a breaker is defective. If the circuit is overloaded, then some of the load must be removed, either by turning off some of the lights or devices plugged into the circuit. If the breaker continues to trip, it’s best to call a qualified electrician to check the circuit.

If your breaker panel lacks labels for the various circuits, it’s a simple matter to note them. It requires two people, one at the panel turning off the circuit breakers, one by one, and the other person watching for the various lights or devices to turn off. Walkie-talkies are handy for this task, but a strong voice also works.


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