Circuits and Runs

Circuits can be divided by type:

• General-purpose or lighting circuits
• Dedicated circuits
• Small-appliance circuits

Lighting circuits include most receptacles in living areas other than the kitchen, bathrooms, and workrooms. This is appropriate for most receptacles because we generally use them for small loads such as floor and table lamps or clock radios. Some receptacles will only be used for night-lights; others might rarely or never be used. Even light fixtures have varying loads depending on the wattage of their lamps. They can vary from 25 watts to 150 watts.

What happens when you plug in something larger such as a room air conditioner? What if you have a water heater or an electric range that also requires large amounts of current? These loads call for dedicated circuits, which are so-named because they only supply power to one specific load.
Dedicated circuits include those for …

• Major appliances.
• Refrigerators.
• Computers.

It’s easy to understand why a major appliance needs a dedicated circuit, but what about refrigerators and computers? Even a large refrigerator-freezer combination is rated at about 500 to 700 watts, and a computer is far less. (My notebook PC is a minuscule 36 watts.) These fall into a different category of dedicated circuits that aren’t based on a demand for electrical current but on their specific activity. It isn’t critical for your refrigerator to be on its own circuit from a power-demand standpoint, but if another load somewhere else on the circuit’s run trips the entire circuit, your refrigerator will shut down, and you will be looking at a lot of spoiled food. Some jurisdictions codes require that the refrigerator be on a dedicated circuit.

Computers don’t store food, but they do store your data. Most people readily agree that we should back up and save our documents and spreadsheets while we’re working on them, but then we cheerfully continue working without doing either.