Lighting/OCD Flashcards
Four fundamental factors governing the visibility of a task?
Size, brightness, contrast and time
The wavelength of visible light ranges from approximately…
380 nanometers - 760 nanometers
What is a ‘colour spectrum’ and how does it work?
When a beam of white light passes through a prism, the beam will spread and separate into individual visible wavelengths.
What wavelength is the eye most responsive to?
555 nanometers / Yellow-Green
What is ‘Colour Temperature’ or ‘Chromaticity’?
A term used to describe the colour of a light source. Expressed in degrees Kelvin (•K)
Low colour temperatures – below 3000 degrees Kelvin have a ______ colour
Warm (reddish)
High colour temperatures – above 4000 degrees Kelvin have a ______ colour
Cool (bluish)
What is colour rendition (CRI)?
The ability of a light source to portray the colour appearance of objects accurately when compared to a standard (reference) light source of the same colour temp colour temperature.
The CRI has a value from ___ to ___.
0 to 100
Light sources with a high CRI cause the least emphasis or distortion of colour. TRUE or FALSE?
True
CRI of an Incandescent lamp?
97 - Excellent
CRI of a Fluorescent, full spectrum 7500?
94 - Excellent
CRI of a Fluorescent, cool white deluxe?
87 - Excellent
CRI of a Compact Fluorescent?
82 - Excellent
CRI of a Fluorescent, warm white?
52 - Fair
Excellent colour rendering ranges from ___ to ___.
75 to 100
Good colour rendering ranges from ___ to ___.
60 to 75
Fair colour rendering ranges from ___ to ___.
50-60
Poor (not suitable for colour-critical applications) ranges from ___ to ___.
0 to 50
The two most fundamental measurements with lighting deals with the ______ of light and the ______.
Total quantity of light
The illumination or lighting level
What is meant by the term ‘Luminous Flux’?
The quantity of light output from a source.
The unit for luminous flux is the Lumen (Lm)
What is meant by the term ‘Luminous Flux Density’?
The density of light flux measured on a surface. (Illumination)
The unit for Illumination is the Lux (Lx)
The lighting level is commonly measured with what?
Photometer
What is meant by the term ‘Inverse Square Law’?
Illumination is inversely proportional to the square of the distance between the light source and the work surface.
E = I / d ^ 2
What is meant by the term ‘Cosine Law of Incidence’?
The illumination on any surface varies as the cosine of the angle of incidence.
Floor flux = I / d ^ 2 x cos
What is meant by the term ‘Luminous Efficacy’?
The ratio of the Light Output (LUMENS) to the Power Input (WATTS).
Average Efficacy of ‘HP Sodium’?
140 Lumens/Watt
Average efficacy of ‘LP Sodium’?
200 Lumens/Watt
Low Pressure Sodium has the highest Lumen Output (200 Lumens/Watt). TRUE or FALSE?
True
Which is the higher frequency light : Infrared or ultraviolet?
Ultraviolet
The actual colour composition of white light can be seen using a ______.
Prism
The ‘colour’ of light is determined by its _______.
Wavelength
The total light output of a lamp is measured in ________.
Lumens
The unit for Illumination is the ______.
Lux
Mercury Vapour provides the best colour rendition? TRUE or FALSE?
False, Incandescent bulb provides the best colour rendition.
High Pressure Sodium has the highest efficacy. TRUE or FALSE?
True
When referring to wavelengths of light, what is a nanometer?
One billionth of a meter
The design of any lighting system invariably involves the consideration of _____ and _____.
Light quantity
Light quality
What is meant by the term ‘seeability’?
The level of peripheral vision and the ability to determine detail.
Lower CRI levels will require higher lighting levels. TRUE or FALSE?
True
What is a ‘Luminaire’?
A complete lighting unit consisting of lamps, wiring channel, reflectors, lens, diffusers and control gear (such as ballasts).
Indirect type of luminaire classification has a upward component of 90-100% and Downward component of 0-10%. TRUE or FALSE?
True
What is meant by the term ‘Luminaire Efficiency’?
Percentage of total Lumens emitted by the luminaire compared to total lumens generated by the lamp alone
What is meant by the term ‘Coefficient of Utilization’?
Percentage of the initial lamp Lumens that reach the task area to produce illumination
The choice of light sources for luminaires are….
Incandescent
Fluorescent
High-intensity discharge (HID)
LED
The wattage input increases as the light output of a lamp decreases with age. TRUE or FALSE?
False, wattage input stays the same
In order to maintain operating efficiency and reduce costs, it is usually advisable to replace lamps in groups when they reach about ___% if rated life.
70% of rated life
A period of operation to ___% lamp failure is the average rated life of a lamp in a group.
50%
The accumulation of dirt on lamps and fixtures can cause light losses if 30% or more. TRUE or FALSE?
True
In terms of Incandescent bulbs, what percentage of the energy input is wasted as heat?
90%
Filaments of ______ are used in Incandescent bulbs because it has a high melting point (3419 degrees C) and a low rate of evaporation.
Tungsten
______ glass is used with Tungsten-Halogen lamps because it can withstand very high temperatures.
Quartz glass
A mixture of nitrogen and argon is usually used in lamps of ___ watts or more to slow evaporation if the filament.
40 watts or more
Code letter ‘S’ is what shape of bulb?
Straight side
Code letter ‘F’ is what shape of bulb?
Flame-shaped
Code letter ‘G’ is what shape of bulb?
Globular
Code letter ‘A’ is what shape of bulb?
Standard line
Code letter ‘T’ is what shape of bulb?
Tubular
Code letter ‘PS’ is what shape of bulb?
Pear-shaped
Code letter ‘PAR’ is what shape of bulb?
Parabolic
Code letter ‘R’ is what shape of bulb?
Reflector
The Medium lamp base has a wattage rating of ___Watts to ___Watts.
40Watts - 300Watts
The Mogul lamp base has a wattage rating of ___Watts to ___Watts.
300Watts and Higher
The most commonly used base for a general service lamp?
Edison base / Screw type
Typical Edison base sizes are….
Mogul, medium, intermediate and candelabra
The screw shell must be connected to the identified conductor. TRUE or FALSE?
True
In terms of connecting wires to a light, Hot goes to the brass screw and the neutral wire goes to the silver screw. TRUE or FALSE?
True
Incandescent lamps have a ______ temperature coefficient.
Positive
High-Wattage lamps have a higher efficacy (Lumen output per watt) than low-wattage lamps of the same voltage. TRUE or FALSE?
True
One 150W lamp produces more light than three 50W lamps? TRUE or FALSE?
True
Low-voltage lamps normally have a longer service life than 120 Volt lamps. TRUE or FALSE?
True
To slow down the rate of filament evaporation, lamps of 40W and higher are filled with ______.
Inert gas
Nitrogen and Argon
_______ lamp is a compact, high-intensity light source that provides a white light output with high Lumen maintenance.
Tungsten-halogen lamp
The Tungsten-halogen lamp is also called a ______.
Quartz-halogen lamp or quartz-iodine lamp
The process which prevents glass from blackening is called the _____ and results in the high Lumen maintenance of the lamp.
Regenerative cycle
For the regenerative cycle to take place, the temperature of the glass must be very _____.
High
A typical Tungsten-halogen lamp is filled with 99.8% argon, 2% nitrogen and trace of iodine Vapour. TRUE or FALSE?
True
______ lamps are an excellent white light source and are often used for studio lighting, glass-case display lighting and any application where good colour rendition is important.
Tungsten-halogen lamps
Because of its operating pressure of five or six atmospheres, tungsten-halogen lamps do not need to be contained within another glass envelope. TRUE or FALSE?
False, Tungsten-halogen lamps MUST be contained within another glass envelope
A ______ is needed in all types of Fluorescent lamps.
Ballast
A ballast performs two main functions. What are they?
High voltage starting necessary to ignite the tube
Limit the current
Open circuit voltage is also referred to as _____.
Striking voltage
Compact Fluorescent Lamps (CFL) have two important advantages over Incandescent lamps. What are they?
Higher efficacy (more Lumens per watt)
Longer life
All Compact Fluorescent Lamps (CFL) require an electronic ballast to operate. TRUE or FALSE?
True
The three most common lamp bases used with Fluorescent Lamps are the…
Bipin
Single pin
Recessed double-contact
4 ways lamp life can be reduced?
Switching too frequently
Operating with the wrong type of ballast
Using excessive supply voltage
Losing cathode preheat during start-up
Light output decreases rapidly over the first ___ hours. Beyond this, the decrease is much more gradual.
100 hours
What is meant by the term ‘seasoning’?
The tubes need to run for 100 hours to establish smooth, non flickering working.
______ ballasts may be required to start a Fluorescent lamp if the ambient temperature is too low.
Cold weather ballasts
Ballasts are rated for noise with letter codes. What are they?
Letters ‘A’ to ‘F’
A = Quietest F = Noisiest
______ lamps, which operate at 430mA, are the most common type of Fluorescent lamp.
Standard rapid-start lamps
______ lamps operate at 800mA.
High-output lamps (HO)
_____ lamps operate at 1500mA.
Very-high-Output lamps (VHO)
Describe the abbreviations for code ‘F40T12CW’.
F - Fluorescent 40 - Watts T - Tubular Shaped 12 - Diameter size (12/8 = 1 1/2") CW - Clear White
Three start types for lamps.
Preheat start
Instant-start
Rapid-start
Slimline lamps are ______ lamps with a single pin at each end.
Instant-start lamps
Black-light tubes use a phosphor that radiates UV in the ___ nm wavelength range which is invisible to the human eye.
350 nanometers
Rapid fluctuations of light in which moving objects are seen in repetitive flashes at successive positions is referred to as _______.
Stroboscopic Effect
To avoid stroboscopic effect where machinery may appear to be stopped, but it in fact is operating can present hazards. To avoid this problem, what can you use?
Lead-lag ballasts
The two lamps operate out of phase and reach their maximum light outputs at different times
______ ballasts change the operating frequency within the lamp from 60Hz to around 20,000Hz, therefore eliminating the stroboscopic effect.
Electronic ballasts
Low-Pressure Sodium (LPS) lamps are still commonly used today because of their good colour rendering. TRUE or FALSE?
False, LPS have a very poor colour rendering and are not commonly used anymore.
Some Low-Pressure Sodium lamps have an efficacy of close to ___ Lumens per watt.
200 lumens per watt
The dull appearance of the outer glass envelope in a typical LPS lamp is due to an internal heat-reflecting coating that further reduces arc-tube heat loss. TRUE or FALSE?
True
Like Fluorescent Lamps, LPS lamps require a ballast to provide a high striking voltage for starting. TRUE or FALSE?
True
Low-pressure Sodium (LPS) lamps take ___ to ___ minutes to reach full intensity.
7 to 10 minutes
Light is pure yellow @ full intensity
The average life of an LPS lamp is rated at?
18,000 hours
LPS lamps contain high levels of Sodium metal and must be disposed of properly. TRUE or FALSE?
True
In an ______ fixture, the ballast houses an auto transformer that steps up the supply voltage to a magnitude sufficient to strike an arc between the two ends of the tube. Without filament heating, this usually occurs at ___ to ___ Volts.
Instant-start fixture
400-500 Volts
Because no cathode preheating is required in an instant-start circuit, the lamp lights, like an incandescent lamp, at the instant the switch is closed. This is referred to as ______.
Cold-cathode starting
Longer + skinnier lamp requires higher striking voltage. TRUE or FALSE?
True
Cathode heaters lower the amount of striking voltage required to arc across the lamp. TRUE or FALSE?
True
The high-voltage end has 1 wire and the low-voltage end has 2 wires in a socket switch. TRUE or FALSE?
True
Low-voltage end acts as a switch
The rapid-start circuit is the most popular type of Fluorescent fixture because it eliminates three major shortcomings of the instant-start fixture.
Large, heavy ballasts
High striking voltage needed for cold cathode starting
Resulting reduced lamp life
Starters are not required for Rapid-start circuit and the striking voltage is ___% to ___% lower than the striking voltage for instant-start lamps.
30% to 50% lower
Circuit breakers should be approved for switching duty for luminaires rated at 347 Volts or less and should be marked ___ for switching duty.
‘SWD’
Conductors are run from one fixture to the next with the fixture Acting line a raceway or conduit. The voltage rating of the wiring must not be less than ___ Volts and the temperature rating must not be less than ___ degrees C.
600 Volts
90 degrees C
Generally, for the same type of Fluorescent lamp, a tube with the smallest diameter and the longest length requires the highest striking voltage. TRUE or FALSE?
True
Ballast ______ is one of the prime causes of failure.
Overheating
A ___ degree C rise in ambient temperature will cut the life of a ballast in half.
10 degree C
A simple method of checking a starter fault is to replace the starter with a good starter. TRUE or FALSE?
True
Fluorescent lamp, low-pressure Sodium lamps and high-intensity discharge (HID) lamps are all ____ lamps in which light is produced by passing electric Current through a gas.
Gas-discharge lamps
Three main types of HID lamps?
Mercury Vapour
Metal Halide
High-pressure Sodium
Mercury Vapour has a longer arc tube compared to a Metal Halide at the same wattage. TRUE or FALSE?
True
In regards to a Mercury Vapour lamp, it takes ___ to ___ minutes to reach full light output.
3 to 7 minutes
If a power outage occurs for an instant, the arc extinguishes and the Mercury Vapour lamp will not re-strike until the lamp cools and the pressure is reduced. Re-strike time is typically ___ to ___ minutes.
4 to 6 minutes
Mercury Vapour lamp has a rated life of ___ hours.
24,000 hours
How can you distinguish Metal Halide lamps from Mercury Vapour lamps?
They are similar in construction, except the Metal Halide arc tube is generally a little shorter
Start up time for Metal Halide lamp?
5 to 7 minutes
Re-striking time for a Metal Halide lamp?
Can be as long as 15 minutes
Life span of a Metal Halide lamp?
15,000 hours
Ceramic discharge tube made from translucent polycrystalline alumina is resistant to Sodium attack and high-temperature melting in a High-pressure Sodium lamp. TRUE or FALSE?
True
High-Pressure Sodium lamps come to full brilliance in ___ to ___ minutes.
3 to 4 minutes
Due to its low operating pressure, the HPS lamp re-strike time is usually less than ___ minute, which is much faster than the other HIDs.
Less than 1 minute
The ______ lamp has the highest efficacy of all HID sources, providing 140 Lumens per watt.
High-Pressure Sodium
High-Pressure Sodium lamps have a rated life of approximately ____ hours?
24,000 hours
Letters indicate the ______ of the bulb and numbers indicate the ______ of the bulb.
Shape of the bulb
Diameters in eights of an inch
Bulb name of letter code ‘B’
Bullet
Bulb name of letter code ‘BT’
Bulged-Tubular
Bulb name of letter code ‘E’
Elliptical
Bulb name of letter code ‘PAR’
Parabolic Aluminized Reflector
Bulb name of letter code ‘T’
Tubular
Letters ‘BU’ indicate what?
Base-up
Letters ‘BD’ indicate what?
Base-down
‘H’ is the chemical abbreviation for ______.
Mercury Vapour
‘M’ or ‘MH’ is the chemical abbreviation for _____.
Metal Halide
‘S’ is the chemical abbreviation for _____.
High-Pressure Sodium
‘LU’ is the chemical abbreviation for ______.
High-Pressure Sodium
‘H36BT-1000/DX’ indicates what?
H = Mercury Vapour 36 = 36 type Ballast 1000 = Wattage DX = Deluxe Colour
‘BT36’ indicates what?
Light bulb
Bulge Tubular, 36 diameter
The life of a ballast is reduced by ___% for each ___ degrees C increase above the design temperature.
50%
10 degrees C
The Reactor Ballast has the simplest design, and is the least expensive. It is used only with Mercury Vapour lamps and is sometimes called ‘lag reactor Ballast’. TRUE or FALSE?
True
Autotransformer Ballast is also called a ‘lag autotransformer ballast’. TRUE or FALSE?
True
Autotransformer Ballast is larger and more expensive than the simple reactor Ballast? TRUE or FALSE?
True
The addition of a capacitor in a autotransformer Ballast improves the circuit power factor (PF) to above 90%. TRUE or FALSE?
True
Both the simple reactor and autotransformer ballasts are limited to situations where the supply voltage does not vary beyond -+5% of nominal supply voltage, and where the voltage dips do not exceed ___ to ___%.
15% to 20%
This Ballast is made up of a high-reactance autotransformer with a series capacitor and is referred to as a _______ Ballast.
Constant Wattage Autotransformer Ballast
Auto-regulator Ballast
The combination of a capacitor and autotransformer in the auto-regulator Ballast gives it a circuit PF in the region of 95% and can handle voltage dips of ___% to ___% without extinguishing the lamp.
40% to 50%
The capacitor is in series with the bulb in the auto-regulator Ballast. TRUE or FALSE?
True
The most common Ballast for Metal-Halide lamps?
Auto-regulator Ballast
The regulator Ballast is made up of two separate windings with a capacitor connected in series with the lamp. This Ballast can tolerate supply voltage variations of -+___% and voltage dips of ___% to ___%.
-+13% voltage variation
50% to 60% voltage dip
The Regulator Ballast is larger and more expensive than the other types? TRUE or FALSE?
True
At the end of lamp life, the arc voltage may become too high for Ballast to provide stable operation and the lamp may be extinguished. As it cooks, it will restart and may continue to cycle ON and OFF. What ballast is this?
High-Pressure Sodium Ballasts
Do not install High-Pressure Sodium ballasts too far from the fixture because the starting spike attenuates (increases) with distance. TRUE or False?
True
The secondary coil of the induction system is represented by the ______ and Mercury Vapour j dude the lamp bulb.
Low-Pressure gas
The purpose of a protective device is to open the circuit before any damage can be done to the ______ and ______.
Conductor
Equipment
Fuses provide over current protection by opening the circuit. TRUE or FALSE?
True
What is meant by the term ‘Overload’?
A moderate increase in current beyond normal rated current value
Typical values of overload currents may range as high as ___ times the normal current.
6 times
Fuses and Circuit Breakers provide open circuit protection? TRUE or FALSE?
False, they open the circuit.
What is meant by the term ‘Over current’?
A sharp, extreme rise in current well above normal current rating caused by a short-circuit.
An overcurrent may range from ___ times to many hundred times the normal current rating.
Six times
Within a few thousandths of a second, a short circuit can become hundreds of times larger than normal operating current. TRUE or FALSE?
True
What is meant by the term ‘short-circuit’?
Larger than normal current that flows outside the normal current path. It is a parallel path of low resistance.
Short-circuit protective devices do not need to respond as quickly as possible. TRUE or FALSE?
False, they need to respond as quickly as possible.
What is meant by the term ‘Ground Fault’?
Another form of short-circuit. It is a short-circuit to ground.
Two main benefits of ground fault protective devices?
Protects against fire damage
Protects human life
Arc Fault Circuit Interrupters (AFCI) protect against what?
Protects against unwanted arcing, reacts to irradiated, in-normal arcs
GFCIs are designed to protect against ______ while AFCIs are primarily designed to protect against ______.
GFCIs = Electrical shock AFCIs = Arcing and/or fire
A standard code fuse has a Current Interrupting Rating of ___ Amps.
10,000 Amps
3 things to check for when using a fuse
Current rating
Voltage rating
Interrupting rating
A high rupture capacity fuse (HRC) has a interrupting rating of ____ Amps.
200,000 Amps
Standard Circuit Breakers have a interrupting rating of ___ Amps.
10,000 Amps
Mechanical forces : High-fault currents, even if only a few thousandth of a second, exert terrific magnetic stress on bus bars and equipment. TRUE or FALSE?
True
Thermal Energy : the intense thermal energy that develops is known as I ^ 2 R x t. If allowed to flow for a longer time, can destroy electrical equipment. TRUE or FALSE?
True
Thermal Energy is minimized by using a current-limiting device that clears a high-fault current within the first half cycle. I.e. A fuse. TRUE or FALSE?
True, the fuse opens within the first half cycle before the prospective Fault current reaches its maximum value.
I_p is the amount of current let through before the fuse is open (let through current). TRUE or FALSE?
True
The usual method of protecting a circuit and equipment is to use a high-speed, specially constructed fuse called _______.
HRC fuse
High Rupturing Capacity
4 critical factors before selecting a protective device
Voltage rating
Current rating
Interrupting rating
Time-current characteristics
______ relates to the ability to quickly extinguish the arc and to prevent the open-circuit voltage in the system from re-striking.
Voltage rating
- Accomplished by fuse length
- Adding sand in the fuse —> HRC Fuse
A 300 Volts fuse can be used on a 700 Volt system. TRUE or FALSE?
False, a 600 Volt fuse can be used on a 240 Volt system for though.
The maximum short-circuit current an overcurrent protective device can safely interrupt without damaging itself is referred to as?
Interrupting rating
Time-delay fuses must be marked with the letter ___.
D
(FRN100) is a time-delay fuse
Non-time-delay fuses must be marked with the letter ___.
P
KTN100) is a non-time-delay fuse
(Low-melting point
Generally, the more severe the fault (the higher the fault Current), the _____ the fuse responds.
Faster
To minimize inconvenience, it is better if the fuse closest to the fault in the circuit opens first. TRUE or FALSE?
True
KTN-R100 is a time-delay or non-time-delay fuse?
Non-time-delay fuse
FRN-R100 is a time-delay or non-time-delay fuse?
Time-delay fuse
What is meant by the term ‘Inverse time-current characteristic’?
The higher the current, the quicker the fuse opens.
A fuse is a simple device that protects the _____ of a circuit.
Conductor
A fuse is an insulated tube containing a strip of metal that has a lower melting point than copper or aluminum. TRUE or FALSE?
True
Two general categories of fuses?
Plug fuses
Cartridge fuses
The plug fuse is sometimes called the ______.
Screw-base or Edison-base fuse
The maximum rating of any fuse is ___ Amps.
30 Amps
The knife type fuse is larger than the ferrule contact fuse? TRUE or FALSE?
True
Max Volts/Amps rating for Ferrule contact fuse?
600 Volts
60 Amps
Max Volts/Amps rating for a knife blade fuse?
600 Volts
600 Amps
A rejection ring must be placed in the fuse holder before this fuse can be inserted into the panelboard.
Type C fuse
A rejection adapter must be installed in the standard fuse holder before this fuse can be inserted.
Type S fuse
Many of the large cartridge fuses are filled with an arc-quenching powder (Silica). This is a fire-extinguishing powder that prevents an arc from continuing or bursting through the tubing of the fuse. TRUE or FALSE?
True
The metal link of a fuse is made up of ______.
Zinc alloy
All renewable fuses are non-time-delay. TRUE or FALSE?
True
What does it mean to ‘spike a fuse’?
Installing a larger link, or more than one link, in the fuse than necessary.
Restrictive segment veins to melt at ___ degrees C for Zinc.
460 degrees C
A fuse that delays opening in an overload situation
Time-delay fuse
Time required for the fuse to open depends on its time-current characteristic curve
A time-delay fuse is sometimes referred to as a ______ fuse.
Dual element fuse
Almost all standard fuses have a an interrupting capacity rating of ____ Amps.
10,000 Amps
Type P fuses have a low melting point and an interrupting capacity rating of _____ Amps.
50,000 Amps
HRC fuses do not deteriorate. They have moisture m-proof fibreglass or ceramic barrels, filled with high-quality ______ sand for arc-quenching.
Silica sand
HRC fuses are interchangeable/not interchangeable?
NOT interchangeable, they are designed in such a way that other fuses will not fit into their holders.
HRCI fuse provides protection from both overloads and short-circuits in cables and equipment. TRUE or FALSE?
True
The HRCII fuse gives short-circuit protection only. TRUE or FALSE?
True
Class R fuses
Available in time-delay and fast-acting types
Normal current rating : 0 to 600 Amps
Interrupting Capacity : 200,000 Amps
Provides a rejection feature and is non-interchangeable
Class R fuse, Ferrule has a Amperage rating up to ___ Amps.
60 Amps
Class J fuses
Available in time-delay and fast-acting types
200,000 Amps interrupting capacity
Designed end-to-end length shorter to make it non-interchangeable
Class T fuses
Faster Acting
Two kings of fuses : HRCI-T and HRC-T
HRCI-T : current rating from 0 to 600 Amps
200,000 Amps interrupting capacity
Very fast acting
Extra-small size provides non-interchangeability
Class L fuses
Available in time-delay and fast-acting types
200,000 Amps interrupting capacity
Non-interchangeable because of its different size and mounting holes
Extension of the Class J fuse
Class CA
Maximum peak let-through current of 8000 Amps
(The level of fault Current reached before the fuse opens)
Non-interchangeable
What is meant by the term ‘let-through current’?
The level of fault current reached before the fuse opens
When selecting a fuse, consider its _____ and _____ ratings and its _____ capacity.
Current rating
Voltage rating
Interrupting capacity
Standard fuses must not be used in circuits with a current over 600 Amps and a voltage over 600 Volts
The Canadian Electrical Code requires that all Circuit Breakers be trip _____.
Trip-free
Function of a circuit breaker?
Protects connected apparatus against overloads and short circuits.
4 main types of moulded-case Circuit Breakers?
Thermal
Thermal-magnetic
Magnetic
Solid state
One of the greatest advantages of the circuit breaker is that it is _____.
Resettable
Many Circuit Breakers have two trip elements
Thermal trip
Magnetic trip
(Magnetic trip element)When a short-circuit occurs, the Fault current passing through the circuit causes the electromagnet to attract an armature mounted on the trip bar. TRUE or FALSE?
True
Magnetic-only breaker only responds to _____.
Over current
CSA calls this breaker an ‘instantaneous trip circuit interrupter’
Has no thermal trip element
Magnetic-only circuit breaker provides ______ protection, but no protection from _____.
Short-circuit protection
Overload
What is a GFI?
A thermal-magnetic breaker that incorporates a solid state, ground-fault sensing circuit to detect ground currents of 5mA or greater.
