Electricity: Understanding How It Works: Basic Code Guidelines


Most codes use a minimum load of 3 watts per sq. ft. (33 watts per sq. m) to calculate the general lighting load and the number of general-purpose lighting circuits that supply light fixtures and receptacles. Keep it simple -- a rule of thumb is one 15-amp circuit for every 600 sq. ft. (56 sq. m) of floor space, or better yet, only install a combination of 10 lights and outlets on a 15-amp general-purpose circuit.

Code also requires a minimum of two 20-amp circuits for kitchen receptacles, one 20-amp circuit for laundry receptacles, one 20-amp circuit for bath room receptacles and a dedicated circuit for central heating equipment.

Generally, receptacle outlets in habitable rooms must be installed so no point measured horizontally along the floor line in any wall space (24 in. / 600 mm or greater) is more than 6 ft. (1.8 m) from a receptacle outlet.

Generally, at least one wall switch-controlled lighting outlet must be installed in every habitable room, bath, hallway, stairway, attached garage and the exterior side of entrances. For habitable rooms other than kitchens and bathrooms, a wall switch-controlled receptacle can be used for the lighting outlet.

Note: The above information is based on United States codes; The Canadian Electrical code (CEC) differs in some areas. (continue ...)


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Ground-fault circuit-interrupter (GFCI)-protected outlets should be installed at countertops so no point measured horizontally along the wall line is more than 24 in. (600 mm) from a receptacle outlet. Islands and peninsulas each must have one GECI outlet. Kitchens. Ground-fault circuit-interrupter (GFCI)-protected outlets should be installed at countertops so no point measured horizontally along the wall line is more than 24 in. (600 mm) from a receptacle outlet. Islands and peninsulas each must have one GECI outlet. Bedrooms, living rooms. All branch circuits that supply 125-volt, 15- and 20-amp outlets in bedrooms must be AECI protected. This includes receptacle and lighting outlets and smoke detectors. Bedrooms, living rooms. All branch circuits that supply 125-volt, 15- and 20-amp outlets in bedrooms must be AECI protected. This includes receptacle and lighting outlets and smoke detectors.
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Last modified: Friday, 2016-12-23 17:30 PST