Getting to know your electrical service panel

July 27, 2015

Home electricity is both essential and dangerous. This guide walks you through some electricity basics to help you keep your home powered and safe.

Getting to know your electrical service panel

Electrical service panel essentials

  • The main service panel is the box holding the circuit breakers or fuses, which can shut off the electricity to individual circuits. Electrical power to the entire house can be controlled by a separate device.
  • In a circuit breaker panel, the main shutoff breaker is usually marked and located at the top of the panel. By turning the switch on the breaker to the "off " position, you can work safely on the wiring throughout the house.
  • Always test the individual circuit before touching any wires, just to be safe.
  • Fuse panels are equipped with either a pullout box containing cartridge fuses, or a lever switch on the side marked for "off" and "on."
  • Your service panel should have a numbered list showing what each circuit controls. If it doesn't, ask an electrician to prepare one.
  • Never touch the main lugs, which are always live even when the breaker is off.

Is your service adequate?

  • If you have circuit breakers in your service panel, chances are you have at least a 100-ampere (or amp) service. Older fuse boxes are usually rated at 60 or 100 amps.
  • The amp rating is typically marked somewhere on the panel. It indicates the maximum amount of electrical service that the house can be wired for.
  • Today, new houses are most often provided with 200 amps, but 100 amps will do for most people. Many people are living just fine with their 60-amp service.
  • Old wiring can be a hazard. If your wiring has frayed or brittle insulation, you may want to consider having your house rewired.

Fuses and circuit breakers

  • The size of a fuse or breaker in your service panel is determined by the expected load on a circuit and the size of the wires in the circuit.
  • Fuses and breakers are designed to blow or trip when the demand for electricity is excessive, before wiring gets dangerously hot.
  • Never replace a fuse with one of larger amperage. Doing so creates a fire hazard.
  • When a breaker trips or fuse blows, try to figure out what caused the overload before resetting the breaker or replacing the fuse.
  • Most happen when you have too many appliances drawing current on the same circuit. Try plugging some of them into receptacles on another circuit. If that doesn't work, one of the appliances on the circuit may need repair.

Understanding your electrical service panel is essential to running your home's power. With some basic knowledge, you can keep your home powered safely and understand why the lights went off.

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