Section C405 Electrical Power and Lighting Systems
This section covers lighting system controls, the maximum lighting power for interior and exterior applications and electrical energy consumption.
Dwelling units within multifamily buildings shall comply with Section R404.1. All other dwelling units shall comply with Section R404.1, or with Sections C405.2.4 and C405.3. Sleeping units shall comply with Section C405.2.4, and with Section R404.1 or C405.3. Lighting installed in walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers shall comply with the lighting requirements of Section C403.10.1 or C403.10.2.
Lighting systems shall be provided with controls that comply with one of the following.
- Lighting controls as specified in Sections C405.2.1 through C405.2.6.
- 2.1. Monitoring occupant activity to brighten or dim lighting when occupied or unoccupied, respectively.
- 2.2. Monitoring ambient light, both electric light and daylight, and brighten or dim artificial light to maintain desired light level.
- 2.3. For each control strategy, configuration and reconfiguration of performance parameters including; bright and dim setpoints, timeouts, dimming fade rates, sensor sensitivity adjustments, and wireless zoning configurations.
Exceptions: Lighting controls are not required for the following:
- Areas designated as security or emergency areas that are required to be continuously lighted.
- Interior exit stairways, interior exit ramps and exit passageways.
- Emergency egress lighting that is normally off.
Occupant sensor controls shall be installed to control lights in the following space types:
- Classrooms/lecture/training rooms.
- Conference/meeting/multipurpose rooms.
- Copy/print rooms.
- Enclosed offices.
- Open plan office areas.
- Storage rooms.
- Locker rooms.
- Other spaces 300 square feet (28 m2) or less that are enclosed by floor-to-ceiling height partitions.
- Warehouse storage areas.
Occupant sensor controls in warehouses shall comply with Section C405.2.1.2. Occupant sensor controls in open plan office areas shall comply with Section C405.2.1.3. Occupant sensor controls for all other spaces specified in Section C405.2.1 shall comply with the following:
- They shall automatically turn off lights within 20 minutes after all occupants have left the space.
- They shall incorporate a manual control to allow occupants to turn off lights.
Occupant sensor controls in open plan office spaces less than 300 square feet (28 m2) in area shall comply with Section C405.2.1.1. Occupant sensor controls in all other open plan office spaces shall comply with all of the following:
- The controls shall be configured so that general lighting can be controlled separately in control zones with floor areas not greater than 600 square feet (55 m2) within the open plan office space.
- The controls shall automatically turn off general lighting in all control zones within 20 minutes after all occupants have left the open plan office space.
- The controls shall be configured so that general lighting power in each control zone is reduced by not less than 80 percent of the full zone general lighting power in a reasonably uniform illumination pattern within 20 minutes of all occupants leaving that control zone. Control functions that switch control zone lights completely off when the zone is vacant meet this requirement.
- The controls shall be configured such that any daylight responsive control will activate open plan office space general lighting or control zone general lighting only when occupancy for the same area is detected.
- Spaces where patient care is directly provided.
- Spaces where an automatic shutoff would endanger occupant safety or security.
- Lighting intended for continuous operation.
- Shop and laboratory classrooms.
Each space provided with time-switch controls shall be provided with a manual control for light reduction in accordance with Section C405.2.2.2. Time-switch controls shall include an override switching device that complies with the following:
- Have a minimum 7-day clock.
- Be capable of being set for seven different day types per week.
- Incorporate an automatic holiday "shutoff" feature, which turns off all controlled lighting loads for not fewer than 24 hours and then resumes normally scheduled operations.
- Have program backup capabilities, which prevent the loss of program and time settings for not fewer than 10 hours, if power is interrupted.
- 5.1. The override switch shall be a manual control.
- 5.2. The override switch, when initiated, shall permit the controlled lighting to remain on for not more than 2 hours.
- 5.3. Any individual override switch shall control the lighting for an area not larger than 5,000 square feet (465 m2).
- 1.1. The time limit shall be permitted to be greater than 2 hours, provided that the switch is a captive key device.
- 1.2. The area controlled by the override switch shall not be limited to 5,000 square feet (465 m2) provided that such area is less than 20,000 square feet (1860 m2).
- 2.1. Spaces that have only one luminaire with a rated power of less than 100 watts.
- 2.2. Spaces that use less than 0.6 watts per square foot (6.5 W/m2).
- 2.3. Corridors, lobbies, electrical rooms and or mechanical rooms.
Spaces required to have light-reduction controls shall have a manual control that allows the occupant to reduce the connected lighting load in a reasonably uniform illumination pattern by not less than 50 percent. Lighting reduction shall be achieved by one of the following or another approved method:
- Controlling all lamps or luminaires.
- Dual switching of alternate rows of luminaires, alternate luminaires or alternate lamps.
- Switching the middle lamp luminaires independently of the outer lamps.
- Spaces with a total of more than 150 watts of general lighting within sidelit zones complying with Section C405.2.3.2 General lighting does not include lighting that is required to have specific application control in accordance with Section C405.2.4.
- Spaces with a total of more than 150 watts of general lighting within toplit zones complying with Section C405.2.3.3.
Exceptions: Daylight responsive controls are not required for the following:
- Spaces in health care facilities where patient care is directly provided.
- Lighting that is required to have specific application control in accordance with Section C405.2.4.
- Sidelit zones on the first floor above grade in Group A-2 and Group M occupancies.
- New buildings where the total connected lighting power calculated in accordance with Section C405.3.1 is not greater than the adjusted interior lighting power allowance (LPAadj) calculated in accordance with Equation 4-9
LPAadj = Adjusted building interior lighting power allowance in watts.
LPAnorm = Normal building lighting power allowance in watts calculated in accordance with Section C405.3.2 and reduced in accordance with Section C406.3 where Option 2 of Section C406.1 is used to comply with the requirements of Section C406.
UDZFA = Uncontrolled daylight zone floor area is the sum of all sidelit and toplit zones, calculated in accordance with Sections C405.2.3.2 and C405.2.3.3, that do not have daylight responsive controls.
TBFA = Total building floor area is the sum of all floor areas included in the lighting power allowance calculation in Section C405.3.2.
Where required, daylight-responsive controls shall be provided within each space for control of lights in that space and shall comply with all of the following:
- Lights in toplit zones in accordance with Section C405.2.3.3 shall be controlled independently of lights in sidelit zones in accordance with Section C405.2.3.2.
- Daylight responsive controls within each space shall be configured so that they can be calibrated from within that space by authorized personnel.
- Calibration mechanisms shall be in a location with ready access.
- Where located in offices, classrooms, laboratories and library reading rooms, daylight responsive controls shall dim lights continuously from full light output to 15 percent of full light output or lower.
- Daylight responsive controls shall be configured to completely shut off all controlled lights.
- Lights in sidelit zones in accordance with Section C405.2.3.2 facing different cardinal orientations [within 45 degrees (0.79 rad) of due north, east, south, west] shall be controlled independently of each other.
- Where the fenestration is located in a wall, the sidelit zone shall extend laterally to the nearest full-height wall, or up to 1.0 times the height from the floor to the top of the fenestration, and longitudinally from the edge of the fenestration to the nearest full-height wall, or up to 2 feet (610 mm), whichever is less, as indicated in Figure C405.2.3.2.
- The area of the fenestration is not less than 24 square feet (2.23 m2).
- The distance from the fenestration to any building or geological formation that would block access to daylight is greater than the height from the bottom of the fenestration to the top of the building or geologic formation.
- The visible transmittance of the fenestration is not less than 0.20.
- The toplit zone shall extend laterally and longitudinally beyond the edge of the roof fenestration assembly to the nearest obstruction that is taller than 0.7 times the ceiling height, or up to 0.7 times the ceiling height, whichever is less, as indicated in Figure C405.2.3.3(1).
- Where the fenestration is located in a rooftop monitor, the toplit zone shall extend laterally to the nearest obstruction that is taller than 0.7 times the ceiling height, or up to 1.0 times the height from the floor to the bottom of the fenestration, whichever is less, and longitudinally from the edge of the fenestration to the nearest obstruction that is taller than 0.7 times the ceiling height, or up to 0.25 times the height from the floor to the bottom of the fenestration, whichever is less, as indicated in Figures C405.2.3.3(2) and C405.2.3.3(3).
- Direct sunlight is not blocked from hitting the roof fenestration assembly at the peak solar angle on the summer solstice by buildings or geological formations.
- The product of the visible transmittance of the roof fenestration assembly and the area of the rough opening of the roof fenestration assembly divided by the area of the toplit zone is not less than 0.008.