Power and Lighting Distribution, Devices, and Luminaires
This domain tests layout rules: where receptacles and lighting outlets are required, how devices are installed, and what limits apply to luminaires. The IRC places power and lighting distribution in Chapter 39 and devices and luminaires in Chapter 40. Many questions are simple measurements against a required spacing rule.
Core rules
- In habitable rooms, receptacle outlets must be installed so that no point along the floor line of any wall space is more than 6 feet from a receptacle. Wall spaces 2 feet or wider require a receptacle.
- Kitchen countertop receptacles must be spaced so that no point along the countertop is more than 24 inches from a receptacle. Islands and peninsulas have their own coverage rules.
- Bathrooms require at least one receptacle within 3 feet of the outside edge of the sink basin, and it must be GFCI protected.
- Lighting outlets are required in habitable rooms, bathrooms, hallways, stairways, garages, and at outdoor entrances, with switch control as required.
- Luminaires must be listed and installed according to labeling, lamp wattage, clearance from combustibles, and closet clearance rules.
Worked example
A bedroom has a 14-foot wall with no door or opening. How many receptacles are needed? One receptacle at the 7-foot mark leaves each end 7 feet away, which exceeds 6 feet. Two receptacles, for example at 3.5 feet and 10.5 feet, keep every point within 6 feet. The spacing rule applies along the floor line, not just at the center of the wall.
Traps
- Measuring from the receptacle to the wall center instead of the farthest point.
- Forgetting that 2-foot wall segments count.
- Overlooking island and peninsula receptacle requirements.
- Installing a luminaire closer to a closet shelf than its listing permits.