Electrical Distribution Systems

The main wires from the electric utility deliver power to your home through the meter. From the meter, power is then connected to your main electrical distribution panels. There are large circuit breakers on the main panel that turn the utility power on and off.

Image of old electrical service wires and mast on roof
Old electrical service wires and mast
From the main panel, electricity is distributed throughout the house via more circuit breakers and additional sub-distriibution panels that may be distributed around the house in key areas. Circuit breakers look like those in the third image below. Each should be clearly labeled so you know what they control. Circuit breakers can be operated like switches but in fact are sensitive safety devices that behave like old fashioned fuses. Older fuses like those shown below would simply burn out, but a circuit breaker will instantly shut the circuit down when it senses an overload, and then can be reset once the problem is corrected.
Fuse systems have essentially been phased out by circuit breakers as the standard for distribution panels since the 1960’s. Note: Although most fuse-based electrical systems have been replaced, there are still some at work in older homes throughout the US. If you have one, I recommend it be inspected by a licensed electrician.
image of an older fuse box with resettable fuses
Small main panel fuse box

Residential circuit breakers are typically spring-loaded switches. When a problem is detected, spring pressure closes the switch and shuts down the circuit. A bit like a mouse trap. Once tripped, the breaker switch will be resting in a position between on and off. To reset the breaker, it must be switched completely off, then pushed back to the on position.
Breakers trip due to a short or overloading of the circuit and do so to prevent fires and electrocution. Trips can be caused by plugging too many appliances into the circuit. Other causes for shorts are: a worn cord, a defective appliance, or operating an appliance with too high a voltage requirement for the circuit. The starting of an electric motor can also trip a breaker.
If a circuit trips repeatedly, you can try this: unplug all items connected to it and reset the breaker. If it trips when nothing is connected to it, you need an electrician. If the circuit remains on, one of the items you unplugged is defective and will require repair or replacement.
Image of an open electrical distribution panel with circuit breakers
Electrical distribution panel


  • Find your main panels and sub panels so you know where they are located in the home and label them.
  • Open the panel door and see if the individual breakers are labeled.
  • If there are any damaged areas, gaps or openings in the panel cover or around the breakers, have an electrician make repairs.


  • I am not aware of any maintenance or repair procedures that are formally recommended by the manufacturers of circuit breakers.
  • Every 3 years: Inspection of the distribution panels and subpanels. The breakers and panel assemblies are subject to corrosion and the adverse effects of heating/cooling, and the intrusion of insects and animals into the interior of the panel enclosures. Since these things could affect proper operation, it is advisable to have a licensed electrician inspect the interior of the panel and test the breakers and their wire connections occasionally. Wire connections should be torqued to manufacturers specified tightness.
image of electrical distribution panels with labeled breakers
Electrical sub panel