Untitled Flashcards Set

LIGHT

Color temperature- describes how a lamp appears when lit/ lighted- measure in degrees kelvin (K)

- The higher the temperature the whiter the light

- The lower the temperature the warmer the light

Color rendering- expresses how colors appear under a given light source

- A shade of red will appear lighter/darker, bluer/orange depending on the spectral properties of the light

Color rendering index- is an indication of how similar an object color is rendered by a non-incandescent source relative to a specific kelvin temperature on the black body line

- The higher the CRI the better the colors will appear

- 100 is the maximum CRI and is an incandescent source

Color constancy: feature of the human color perception system which ensure that the perceived color of object remains relatively constant under varying illumination conditions

The measure of illumination is in Footcandles FC or lux

Lighting schedules- detailed document that outlines the lighting design, installation, and control requirements for a building or space.- fixture type, location, wattage, voltage, control options, and adjustments

Lumen- is the rate a light source emits light energy/ they measure the total amount of light coming from a lamp (more lumens=brighter)

Candlepower- describes the intensity of the light source and is measured in candles

LUX- the SI system of units for everywhere but the USA (footcandles)

Types of HID sources- metal halide, other MH, high pressure mercury, high pressure sodium, low pressure sodium

Discharge lamps- type of light source that produces light by passing an electric current through a gas, which ionizes and emits visible light rather than a glowing hot solid tungsten filament emits the light

Ballasts- electrical device used to regulate the current and voltage in lamps, particularly in discharge lamps such as fluorescent lights, metal-halide lamps, and sodium vapor lamps. are used in all discharge lamps in order to operate

Light design/ layering- using different types of light for different purposes to ensure both the functionality and aesthetics of the space.

After image- photoreceptors (cone cells) become over stimulated and lose the ability to adapt. The negative or reverse color will appear in its place

Categories of lighting – task lighting, ambient lighting, accent lighting,Decorative lighting, natural, emergency light

ELECTRICAL

Electrical panel schedules- an enclosure where electric power is allocated among individual circuits

Main components of a conductor (wire)-

- Hot- the hot blade is connected to a black conductor carrying 155v-120v

- Neutral- white conductor that provides a complete circuit for electron flow

- Ground- carries current only on the event of an electrical fault/ may be uninsulated in residential applications, green on commercial

Conductors (wires)- materials that accommodate electron flow (transmit electricity efficiently)

- Copper is used for all duplex lighting and circuits

- Aluminum used for service wiring at service drops or buried lines

Race ways- special conduits

Conductor insulation- thermoplastic, and thermoset

- Protects the underlying cable core from mechanical, moisture, and chemical damage during the insulation and service life – enhance flame resistance

GFI Ground fault interrupter- located in wet areas of a building, GFI breakers in the panel protect an entire circuit

Transformer- super efficient machine for changing voltages, magnetic field created by the alternating current in a primary coil to induce a current in a secondary coil at a different voltage

Water electricity analogy

- Voltage = Water pressure: water stored at high level, the higher the stronger its pushed when it flows down

-Current = water flow: the amount of water moving is like the flow of electrons in a circuit

-Resistance = friction/obstacles: just as pipes and obstacles slow water down, resistance limits the flow of electrons

-Power = voltage x current: more pressure & more flow together create more power, just like a water wheel works best w/ both high water pressure & strong flow

Ohm’s law- exist around wires carrying a current, defines the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit V= I x R to find current: I = V/R to find resistance: R= V/I

Types of electricity- static, normal (current) AC/DC

Types of circuits- close/Open, series, parallel

- Series - type of electrical circuit in which components (such as resistors, light bulbs, or other electrical devices) are connected end-to-end, forming a single path for the current to flow.

- Parallel- the components are connected across the same two points, forming multiple paths for the current to flow.

Electrical power- the product of voltage and current, any amount of power can be produced with enough cells

- The electrical power produced is equal to the product of the current and voltage.

- W= I x V W- power in watts I= current amperes V=voltage in volts

Electrical energy- produced is equal to the power times the amount of time that the power is produced.

- E= W x H E= electrical energy in watt-hours H= time in hour

the number of watt-hours is usually very large, electrical energy is usually measured in kilowatt-hours.

- E= k X W X H 1 kw= 1000 w

Electromagnetic fields- electric fields present when voltage is present, magnetic fields created by flow of electrons, magnetic fields exist around wire carrying a current & on electrical devices

Acoustics

Reverberation time- dependent on the surface

- Short reverberation time- (rapid rate of decay or face reduce sound reflection produces a special condition described as acoustically dead

- Long reverb time- sound continues to reflect in a unimpeded fashion between surfaces an therefore decays more slowly, producing acoustically “live” spaces

Reverberation- the subtle (less than .01 second) prolongation of the sound in the room caused by continued multiple reflections: reflected sound waves combine with your original sound waves to create a prolonged sound

Echo- the long delayed discrete sound reflections of sufficient intensity to be clearly heard above the general reverberation on a space

Sound intensity- (sound pressure) the average deviation in pressure. These pressure deviations produce a sensation of hearing by causing the listener’s ear drum to vibrate

Decibels (db)- the measure of sound intensity/ measured in terms of the threshold levels at which the person can detect sounds signals at various frequencies:

- 0db in the threshold for audibility

- 130 db is the threshold of pain

- 140 in standing near a jet engine

Sound isolation- to the process of preventing the transmission of sound from one space to another. Ex: Soundproofing vs. Sound Absorption/ floating floors/

Sound absorption- process of reducing the intensity of sound by capturing sound waves and converting their energy into heat. using materials that have the ability to absorb sound, rather than reflect or transmit it. Ex: acoustic foam, fiberglass, acoustic panel

Sound transmission class (STC)- evaluation & prediction of noise transmission/airborne sound through a barrier (walls or building elements)

- a rating for how well a building partition attenuates airborne sound > Rating values range from 10 – 70 > higher the value, less sound transmission occurs through material

Wall construction to reduce sound transmission- goal is to create a barrier that minimizes the passage of both airborne sounds, and structure-borne sounds

- increase mass (triple layer of drywall, concrete or brick Etc.)

- increase insulation- fiberglass, cellulose insulation

- provide structural discontinuity

- provide isolation

- decoupling- separating layers of the wall structure to prevent vibrations from traveling through the wall directly

Mask environmental noises- using sound to mask the surrounding noise instead of building walls and floors that will have a sufficiently high transmission loss (TL) Ex: white noise

Reflector shapes- convex (good distribution), flat, and Concave Reflectors (causes echoes, should be avoided)

White noise- a broad spectrum of sound energy , can be continuous or intermittent, has an equal amount of energy per Hz of bandwidth

Attenuation- the gradual reduction in sound intensity as a result of distance and sound absorptive surfaces

Creep- the transfer of sound along a concave surface (pantheon dome) a voice on one side of the dome can be clearly head on the opposite side

Variable room absorption- treatments used to modify room acoustics by adjusting the amount of absorptive and reflective surfaces

Natural amplification- phenomenon where certain materials, structures, or environments enhance or amplify sound without the use of artificial electronic equipment (like microphones or speakers).

- 1. Develop ceiling and wall forms to maximize the useful reflector surface 2. Use room finishes 3. Avoid focusing effects 4. arrange for blending of sound diffusion through faceting of major surfaces 5. Manipulate forms in a manner that prevents echo

Definitions

Illumination- is the amount of light (lumens) falling on a surface and is measured in footcandles

Footcandles- amount of light (lumens) falling on 1 square foot of surface

Inverse square law- as the distance of light increases, the same light energy is distributed over a greater spherical surface area- illumination is reduces

Efficiency- ratio of light output to energy input OR ratio of lumens to watts

Restrike time- how long it takes to reenergize a lamp that has been extinguished

Brightness ratio- the difference in light levels between 2 areas in a space (determines how comfortable and functional the lighting is)

Task Lighting- lighting designed for a specific function or activity

Pendant lighting- hanging fixtures suspended from the ceiling

Luminaries- The technical term for lighting fixtures not just “lamps”

Shades & diffusers- components used to control glare and soften light by blocking or scattering illumination

Point source lighting- great accent and task lighting but may create harsh shadows

Spread/elongated light- provides even, comfortable lighting for large spaces

Lighting circuits- a specific type of electric circuit designed to control the lighting system within a building or an area.

Electricity- the energy created by the movement of electron (tiny, charged particles) through a conductor like a wire

Voltage- the push that drives electrons

Current- the flow of electrons

Resistance- the opposition that slows down the electron flow

Inductive reactance- is a measure of the opposition to the flow of alternating current (AC) through an inductor.

Electric circuits- closed loop or path through which electric current flows

Transformer- Super-efficient machine for changing voltages/ magnetic field created by the alternating current in a primary coil to introduce a current in secondary coil at a different voltage

Electromagnetic fields- electric fields present when voltage is present, magnetic fields created by flow of electrons, magnetic fields exist around wire carrying a current & on electrical devices

Duplex circuits- many outlets can be connected on a single circuit

Dedicated duplex circuit- dedicated for a specific use

Bus bar- metal bar that carries current/ Two hot wires from the utility transformer are connected through 2 separate bus bars. circuit breakers ‘snap’ onto the bus bars

circuit breakers- a switch that opens to disconnect electrical power when it senses excess current

MCB- Main circuit breaker, will cut off all electrical power

Duplex outlet: receptacle for the electrical connection to serve one or two appliances

Volt ( V ) : the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points

Watt- measures the rate of energy conversion or transfer

Ampere- measure the amount of electric charge passing a point in an electric circuit per unit time

Romex – trade name f or nonmetallic-sheathed cable. Consists of 2 or more insulated conductors and ground wire surrounded by moisture resist ant plastic.

Sound- a vibration in an elastic medium

Airborne Transmission- Direct passage of sound through openings and pores

Cycle- the full circuit by the particle, corresponds to wavelength

Frequency- the rate of vibration at the source or the number of complete cycles per second/ high rates of vibration=short wavelength(high sound) low vibration = longer wavelengths (lower sound)

Hertz (HZ)- the measure of frequency in cycles per second

Intensity- (sound pressure) the average deviation in pressure/ the produce a sensation of hearing by causing the listener’s ear drum to vibrate

Amplitude- the max displacement of particle to either side of its normal position during a vibration (peaks through soundwave)

Compression- the point in as sound wave where the particles are at max pressure

Refraction- the point where the particles are at min pressure

Impact noise- sound generated by a object striking, vibrating or sliding against a component of the building (footsteps, dropped objects,)

Diffusion- scattering of a sound wave in many directions & occurs when surface size equals wavelength of sound

Diffraction- bending of sound waves around an object

Audience attenuation- gradual reduction in sound intensity as a result of distance & sound absorptive surface

Flutter echo- an echo that occurs between parallel and non-parallel sound reflective surfaces when the source of the sound is between them

Direct wave- sound that reaches the listener w/out reflection from another surface

Reflected wave- sound that is received by the listener after the direct wave and after the wave is reflected by another surface

Electric Lighting Basics

Visible light is the small portion of the electromagnetic spectrum that the human eye is sensitive to

Human sensitivity is different than other animals: most animals do not see within the same range as humans- birds and bees sensitive to ultra violet, snakes are sensitive to infrared

Inverse square law calculation E= CP/r^2 E= illumination level (fc), CP= Candlepower of source of light (cd) r= distance from point source (ft)

HD lamps take a period of time to cool down before the electric arc can be restruck

The color composition of a light source can be drawn by plotting the amount of energy at each wavelength

Spectral energy distribution curve- show SED across the visual wavelengths, may be continuous: having energy across the wavelength, discontinuous: showing spikes of energy at certain wavelength, or no energy in other wavelength

White light- combo of all visible color of the spectrum

Prisms bend short wavelengths which spreads the light into distinct bands of color

3 light primaries- red, blue, and green (white) 3 pigment primaries- magenta, yellow, & cyan (black)

Pupil: where light enters the eye

Iris: muscle which adjusts the opening of the pupil to accommodate varying brightness level

Retina: the light sensitive lining at the back of an eye- cones: cells that are sensitive to color- Rods: cells that respond to motion & dim lighting cond.

Fovea: consists mostly of cone cells. Sharpe vision occurs in a 2 degree cone around the fovea

Human eye sensitivity & spectrum- peaks at the yellow/green decreases towards blue/red

3:1- between a task area and its surrounding (desk vs adjacent surfaces)

5:1- between a task area and distant surrounding (work desk vs background wall

10:1 (max)- between the brightest and darkest part of a room. Higher ratio creates discomfort

Reading lamp numbers- The letter: represent the shape of the bulb The number: represents the diameter of the bulb in eighths of an inch

- A12- “A” stands for Arbitrary which is a common household bulb shape “12” means the bulb is 12 eighths of an inch in diameter or 1.5 inch wide

Common bulb shapes and their meaning

- A (arbitrary)- classic household bulb shape

- T (tubular)- straight tube-shaped bulbs

- PAR (parabolic Aluminized reflector)- bulbs designed for focused, directional lighting light spotlights

- MR (multifaced reflector)- smaller highly focused bulbs often used in track lighting

- G (globe)- round decorative bulbs, such as G25 used in vanity lights

A12- about1.5” A19- 2.375” T8- 1” PAR38- 4.75” MR16- 2” G25- 3.125”

Foot candle= candle power/ square footage If 1000lm/100 sqft= 10 fc

Museums need precise lighting to showcase art without glare, office enough light to avoid eye strain while working, hospital high illuminance for medical procedures

If a LED light emits 1600 lumens and consumes 15 watts

Task: provides focused, direct light where precision is needed/ Ex: desk lamp, under cabinet lighting, step lighting, surgical lights

Pendant lights: bring light closer to a specific area, creating both functionality & ambiance/ EX dinning table pendant lights

Luminaries: encompasses the entire lighting unit, including the lamp, housing, optics, & electrical components EX/ recessed downlights, wall sconces, track light systems

Shades & diffusers: improves visual comfort but may reduce efficiency by absorbing or reducing light/ Ex fabric lamp shade, frosted glass, acrylic

Curved Solid lines are used to show circuits serving lighting fixtures

Electricity

Static electricity- created by friction, produces very high voltage but extremely low current, discharges as a brief spark/ usually harmless unless it ignites something flammable

Normal (current) electricity- Direct current: voltage & current constant, batteries emergency power/ alternating current: voltage & current change rhythmically , most electricity in buildings, change voltage via transformer

Power factor—

Ohm’s Law for pure resistors (DC or simple AC) Formula I= E/R Applies to devices that operate purely by resistance (incandescent lamp)

- Doesn’t always work because it rely on magnetic fields & are classified as inductors (like motor or ballas)

- In these devices theres an extra opposition to current flow not captured by simple resistance

Impedance (Z): Combines resistance (R) and inductive reactance(Xₗ) into one value, Modified Ohm’s Law: I = E / Z, Measured in ohms (Ω), just like resistance

Inductive reactance formula X l=2πfL XL = Inductive reactance (measured in ohms, Ω) f = Frequency of the alternating current (measured in hertz, Hz). L = Inductance of the coil (measured in henries, H)

electric power producers such as generators, batteries, fuel cells, and photovoltaics (PV) can be organized in series or parallel circuits

generators of the national power grid are in parallel / flashlights usually have two or three batteries in series

Power= energy/ time energy= power x time electrical energy= watts x hours – wh

Electrical energy- watts x hours= wh: wh: 100Wh=1kWh

Electrical safety- severity of electrical shock a function of amount of current flowing through the body/ smallest current that people can feel is 1 milliampere (0.001 A)/ 100 milliamperes (0.1 A) can be lethal/ above 50 volts dangerous

Types of circuits

- Service: includes conductors, conduit,, and accessories that connect the home t to the utility transformer

- Lighting circuits – Commercial: light and duplex circuits are separated. – residential: a single circuit can serve both duplex outlets & lighting fixture

- 240 volt circuits – Used for electric water heaters, ranges, ovens, dryers, a i r conditioners & heat pumps – Appliances without plugs are hard wired – connected directly

Code requires all electrical systems be grounded

3rd wire cable redirects live currents into the ground to prevent a person from shock when there is a shorted circuit

GFI is a device that is able to detect small current leaks and disconnect the power the circuit preventing electrical shock

NEC requires all exterior receptacle outlet be GFI

Fault- may result from worn insulation, loose connections, wet connections, a small current flow through humans may cause death

Conductor sizes: #14 – smallest conductor permitted in buildings-carries 15 amps safely ; used for switches – #12 – carries 20 amps; preferred size for home duplex and lighting circuits – #10 – water heater – #6 – range – #4 - carries 200 amps

Romex: 3 varieties – NM – non metallic – NMC – wet or corrosive surroundings – NF – Underground installations

- NM is permitted only in residential occupancies and only i n concealed locations ( in walls ceilings)/ low cost but difficult to add or change circuits after insulation

• Junction Box – protective box to prevent contact between conductors and construction materials • Available in steel and plastic • Secured to wood studs or ceiling joist • Codes require boxes to be accessible when construction is complete

Steel conduits: galvanized steel: 3 types- 1. Types MC, AC, & MX armored steel, quick & cheap; flexible 2. EMT electrical metallic tubing, lightweight & connections by compression fitting or set screws 3. IMC & rigid- heavier, assembles with threaded connections

Aluminum conduit: can be substituted for galvanized but never in contact with concrete Plastic conduit: PVC and others

Installing conductors- flexible tape: flexible metal strip to pull conductors through conduit

Special conduits- cable trays, busways, raceway, under floor duct

Acoustical & Noise control

Sound- vibrating particles move an extremely small amount to either side of their normal positions/ each bumps adjacent particles and imparts most of its motion & energy to them, thus transferring the sound vibration

Airborne Transmission: the intensity of the transmission will depend on which path offers the path of least resistance

impact isolation class (IIC)- the ability if a given floor/ceiling assembly to resist and subsequently reduce common impact sounds

Wall assemblies: sound transmission & noise reduction can be reduced in 3 ways--- 1. Increase mass 2. Increase insulation 3. Provide structural discontinuity 4. Provide isolation

The perception of loudness is affected by four factors: 1. Sound pressure 2. The age and health of the hearer 3. The frequency of the sound 4. The presence of a masking sound