Electrical And Lighting Flashcards
Ideal brightness ratio between a task and adjacent surroundings to minimize glare
Under 1:1/3
Security system technologies
Photoelectric cells: protect perimeter entry points by passing a beam from one point to another and sound an alarm when the beam is broken.
Pressure sensors: protect a room by detecting pressure changes in the floor
Ultrasonic detectors: protect a room by using high frequency sound waves to sense intruders
Photoelectric beams: use infrared beams to protect a room
Elevator operating systems
Best for a 4 story apartment building: selective collective operation. Works best with more than one car so they can be making simultaneous trips.
Best for large office building: computerized controls. Programmed based on data about building traffic patterns and analysis of the most important calls.
Other types: single automatic push button control and collective control.
Three types of PV cells
Crystalline: best power generators and most expensive
Polycrystalline: produce less power but are more competitively priced
Amorphous: aka thin film, produce the least power but can be applied into other building materials such as roof tiles
Daylight factor
Ratio of illuminance on horizontal surface outside vs inside on an overcast day. Expressed as percentage or factor (2% or 2). Ideal average varies from 1.5% to 4% for different tasks. 5% or more indicates excessive glare or heat gain.
DF (average) = 0.2 (window area / floor area)
Maximum spacing for electrical outlets above a kitchen counter
4’
Any counter more than 1’ long requires its own
Clearances required for electrical equipment and panels?
3’ deep x 30” wide clearance in front
6’ headroom clearance or height of equipment, whichever is greater
General max spacing between electrical outlets
12’
Each wall more than 2’ must have outlet
No point along wall should be more than 6’ from an outlet (but cannot be across door or fireplace)
For a home, there must be an outlet for every 575 SF
Electrical outlet heights
Between 1’-6” and 5’-6”
Equipment that gets its own dedicated circuit
MW, stove, refrigerator, DW, W/D
Locations prohibited for electrical outlets
Floor in a garage
Above a sink or tub
Above an electric baseboard
Electrical distribution systems
120/208:
120/240:
277/480: Use for space larger than 40,00
Coefficient of utilization
Percentage of total lamp lumens that reach the work plane
Mercury lights
Blue light like the planet. Poor color rendition and efficiency so not used much anymore.
Metal halide lamps
Good color rendition, efficiency and long life (20,000 hours)
