Lighting/OCD Flashcards
1
Q
Four fundamental factors governing the visibility of a task?
A
Size, brightness, contrast and time
2
Q
The wavelength of visible light ranges from approximately…
A
380 nanometers - 760 nanometers
3
Q
What is a ‘colour spectrum’ and how does it work?
A
When a beam of white light passes through a prism, the beam will spread and separate into individual visible wavelengths.
4
Q
What wavelength is the eye most responsive to?
A
555 nanometers / Yellow-Green
5
Q
What is ‘Colour Temperature’ or ‘Chromaticity’?
A
A term used to describe the colour of a light source. Expressed in degrees Kelvin (•K)
6
Q
Low colour temperatures – below 3000 degrees Kelvin have a ______ colour
A
Warm (reddish)
7
Q
High colour temperatures – above 4000 degrees Kelvin have a ______ colour
A
Cool (bluish)
8
Q
What is colour rendition (CRI)?
A
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.
9
Q
The CRI has a value from ___ to ___.
A
0 to 100
10
Q
Light sources with a high CRI cause the least emphasis or distortion of colour. TRUE or FALSE?
A
True
11
Q
CRI of an Incandescent lamp?
A
97 - Excellent
12
Q
CRI of a Fluorescent, full spectrum 7500?
A
94 - Excellent
13
Q
CRI of a Fluorescent, cool white deluxe?
A
87 - Excellent
14
Q
CRI of a Compact Fluorescent?
A
82 - Excellent
15
Q
CRI of a Fluorescent, warm white?
A
52 - Fair
16
Q
Excellent colour rendering ranges from ___ to ___.
A
75 to 100
17
Q
Good colour rendering ranges from ___ to ___.
A
60 to 75
18
Q
Fair colour rendering ranges from ___ to ___.
A
50-60
19
Q
Poor (not suitable for colour-critical applications) ranges from ___ to ___.
A
0 to 50
20
Q
The two most fundamental measurements with lighting deals with the ______ of light and the ______.
A
Total quantity of light
The illumination or lighting level
21
Q
What is meant by the term ‘Luminous Flux’?
A
The quantity of light output from a source.
The unit for luminous flux is the Lumen (Lm)
22
Q
What is meant by the term ‘Luminous Flux Density’?
A
The density of light flux measured on a surface. (Illumination)
The unit for Illumination is the Lux (Lx)
23
Q
The lighting level is commonly measured with what?
A
Photometer
24
Q
What is meant by the term ‘Inverse Square Law’?
A
Illumination is inversely proportional to the square of the distance between the light source and the work surface.
E = I / d ^ 2
25
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
26
What is meant by the term 'Luminous Efficacy'?
The ratio of the Light Output (LUMENS) to the Power Input (WATTS).
27
Average Efficacy of 'HP Sodium'?
140 Lumens/Watt
28
Average efficacy of 'LP Sodium'?
200 Lumens/Watt
29
Low Pressure Sodium has the highest Lumen Output (200 Lumens/Watt). TRUE or FALSE?
True
30
Which is the higher frequency light : Infrared or ultraviolet?
Ultraviolet
31
The actual colour composition of white light can be seen using a ______.
Prism
32
The 'colour' of light is determined by its _______.
Wavelength
33
The total light output of a lamp is measured in ________.
Lumens
34
The unit for Illumination is the ______.
Lux
35
Mercury Vapour provides the best colour rendition? TRUE or FALSE?
False, Incandescent bulb provides the best colour rendition.
36
High Pressure Sodium has the highest efficacy. TRUE or FALSE?
True
37
When referring to wavelengths of light, what is a nanometer?
One billionth of a meter
38
The design of any lighting system invariably involves the consideration of _____ and _____.
Light quantity
| Light quality
39
What is meant by the term 'seeability'?
The level of peripheral vision and the ability to determine detail.
40
Lower CRI levels will require higher lighting levels. TRUE or FALSE?
True
41
What is a 'Luminaire'?
A complete lighting unit consisting of lamps, wiring channel, reflectors, lens, diffusers and control gear (such as ballasts).
42
Indirect type of luminaire classification has a upward component of 90-100% and Downward component of 0-10%. TRUE or FALSE?
True
43
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
44
What is meant by the term 'Coefficient of Utilization'?
Percentage of the initial lamp Lumens that reach the task area to produce illumination
45
The choice of light sources for luminaires are....
Incandescent
Fluorescent
High-intensity discharge (HID)
LED
46
The wattage input increases as the light output of a lamp decreases with age. TRUE or FALSE?
False, wattage input stays the same
47
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
48
A period of operation to ___% lamp failure is the average rated life of a lamp in a group.
50%
49
The accumulation of dirt on lamps and fixtures can cause light losses if 30% or more. TRUE or FALSE?
True
50
In terms of Incandescent bulbs, what percentage of the energy input is wasted as heat?
90%
51
Filaments of ______ are used in Incandescent bulbs because it has a high melting point (3419 degrees C) and a low rate of evaporation.
Tungsten
52
______ glass is used with Tungsten-Halogen lamps because it can withstand very high temperatures.
Quartz glass
53
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
54
Code letter 'S' is what shape of bulb?
Straight side
55
Code letter 'F' is what shape of bulb?
Flame-shaped
56
Code letter 'G' is what shape of bulb?
Globular
57
Code letter 'A' is what shape of bulb?
Standard line
58
Code letter 'T' is what shape of bulb?
Tubular
59
Code letter 'PS' is what shape of bulb?
Pear-shaped
60
Code letter 'PAR' is what shape of bulb?
Parabolic
61
Code letter 'R' is what shape of bulb?
Reflector
62
The Medium lamp base has a wattage rating of ___Watts to ___Watts.
40Watts - 300Watts
63
The Mogul lamp base has a wattage rating of ___Watts to ___Watts.
300Watts and Higher
64
The most commonly used base for a general service lamp?
Edison base / Screw type
65
Typical Edison base sizes are....
Mogul, medium, intermediate and candelabra
66
The screw shell must be connected to the identified conductor. TRUE or FALSE?
True
67
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
68
Incandescent lamps have a ______ temperature coefficient.
Positive
69
High-Wattage lamps have a higher efficacy (Lumen output per watt) than low-wattage lamps of the same voltage. TRUE or FALSE?
True
70
One 150W lamp produces more light than three 50W lamps? TRUE or FALSE?
True
71
Low-voltage lamps normally have a longer service life than 120 Volt lamps. TRUE or FALSE?
True
72
To slow down the rate of filament evaporation, lamps of 40W and higher are filled with ______.
Inert gas
Nitrogen and Argon
73
_______ lamp is a compact, high-intensity light source that provides a white light output with high Lumen maintenance.
Tungsten-halogen lamp
74
The Tungsten-halogen lamp is also called a ______.
Quartz-halogen lamp or quartz-iodine lamp
75
The process which prevents glass from blackening is called the _____ and results in the high Lumen maintenance of the lamp.
Regenerative cycle
76
For the regenerative cycle to take place, the temperature of the glass must be very _____.
High
77
A typical Tungsten-halogen lamp is filled with 99.8% argon, 2% nitrogen and trace of iodine Vapour. TRUE or FALSE?
True
78
______ 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
79
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
80
A ______ is needed in all types of Fluorescent lamps.
Ballast
81
A ballast performs two main functions. What are they?
High voltage starting necessary to ignite the tube
Limit the current
82
Open circuit voltage is also referred to as _____.
Striking voltage
83
Compact Fluorescent Lamps (CFL) have two important advantages over Incandescent lamps. What are they?
Higher efficacy (more Lumens per watt)
Longer life
84
All Compact Fluorescent Lamps (CFL) require an electronic ballast to operate. TRUE or FALSE?
True
85
The three most common lamp bases used with Fluorescent Lamps are the...
Bipin
Single pin
Recessed double-contact
86
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
87
Light output decreases rapidly over the first ___ hours. Beyond this, the decrease is much more gradual.
100 hours
88
What is meant by the term 'seasoning'?
The tubes need to run for 100 hours to establish smooth, non flickering working.
89
______ ballasts may be required to start a Fluorescent lamp if the ambient temperature is too low.
Cold weather ballasts
90
Ballasts are rated for noise with letter codes. What are they?
Letters 'A' to 'F'
```
A = Quietest
F = Noisiest
```
91
______ lamps, which operate at 430mA, are the most common type of Fluorescent lamp.
Standard rapid-start lamps
92
______ lamps operate at 800mA.
High-output lamps (HO)
93
_____ lamps operate at 1500mA.
Very-high-Output lamps (VHO)
94
Describe the abbreviations for code 'F40T12CW'.
```
F - Fluorescent
40 - Watts
T - Tubular Shaped
12 - Diameter size (12/8 = 1 1/2")
CW - Clear White
```
95
Three start types for lamps.
Preheat start
Instant-start
Rapid-start
96
Slimline lamps are ______ lamps with a single pin at each end.
Instant-start lamps
97
Black-light tubes use a phosphor that radiates UV in the ___ nm wavelength range which is invisible to the human eye.
350 nanometers
98
Rapid fluctuations of light in which moving objects are seen in repetitive flashes at successive positions is referred to as _______.
Stroboscopic Effect
99
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
100
______ ballasts change the operating frequency within the lamp from 60Hz to around 20,000Hz, therefore eliminating the stroboscopic effect.
Electronic ballasts
101
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.
102
Some Low-Pressure Sodium lamps have an efficacy of close to ___ Lumens per watt.
200 lumens per watt
103
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
104
Like Fluorescent Lamps, LPS lamps require a ballast to provide a high striking voltage for starting. TRUE or FALSE?
True
105
Low-pressure Sodium (LPS) lamps take ___ to ___ minutes to reach full intensity.
7 to 10 minutes
| Light is pure yellow @ full intensity
106
The average life of an LPS lamp is rated at?
18,000 hours
107
LPS lamps contain high levels of Sodium metal and must be disposed of properly. TRUE or FALSE?
True
108
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
109
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
110
Longer + skinnier lamp requires higher striking voltage. TRUE or FALSE?
True
111
Cathode heaters lower the amount of striking voltage required to arc across the lamp. TRUE or FALSE?
True
112
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
113
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
114
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
115
Circuit breakers should be approved for switching duty for luminaires rated at 347 Volts or less and should be marked ___ for switching duty.
'SWD'
116
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
117
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
118
Ballast ______ is one of the prime causes of failure.
Overheating
119
A ___ degree C rise in ambient temperature will cut the life of a ballast in half.
10 degree C
120
A simple method of checking a starter fault is to replace the starter with a good starter. TRUE or FALSE?
True
121
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
122
Three main types of HID lamps?
Mercury Vapour
Metal Halide
High-pressure Sodium
123
Mercury Vapour has a longer arc tube compared to a Metal Halide at the same wattage. TRUE or FALSE?
True
124
In regards to a Mercury Vapour lamp, it takes ___ to ___ minutes to reach full light output.
3 to 7 minutes
125
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
126
Mercury Vapour lamp has a rated life of ___ hours.
24,000 hours
127
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
128
Start up time for Metal Halide lamp?
5 to 7 minutes
129
Re-striking time for a Metal Halide lamp?
Can be as long as 15 minutes
130
Life span of a Metal Halide lamp?
15,000 hours
131
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
132
High-Pressure Sodium lamps come to full brilliance in ___ to ___ minutes.
3 to 4 minutes
133
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
134
The ______ lamp has the highest efficacy of all HID sources, providing 140 Lumens per watt.
High-Pressure Sodium
135
High-Pressure Sodium lamps have a rated life of approximately ____ hours?
24,000 hours
136
Letters indicate the ______ of the bulb and numbers indicate the ______ of the bulb.
Shape of the bulb
| Diameters in eights of an inch
137
Bulb name of letter code 'B'
Bullet
138
Bulb name of letter code 'BT'
Bulged-Tubular
139
Bulb name of letter code 'E'
Elliptical
140
Bulb name of letter code 'PAR'
Parabolic Aluminized Reflector
141
Bulb name of letter code 'T'
Tubular
142
Letters 'BU' indicate what?
Base-up
143
Letters 'BD' indicate what?
Base-down
144
'H' is the chemical abbreviation for ______.
Mercury Vapour
145
'M' or 'MH' is the chemical abbreviation for _____.
Metal Halide
146
'S' is the chemical abbreviation for _____.
High-Pressure Sodium
147
'LU' is the chemical abbreviation for ______.
High-Pressure Sodium
148
'H36BT-1000/DX' indicates what?
```
H = Mercury Vapour
36 = 36 type Ballast
1000 = Wattage
DX = Deluxe Colour
```
149
'BT36' indicates what?
Light bulb
| Bulge Tubular, 36 diameter
150
The life of a ballast is reduced by ___% for each ___ degrees C increase above the design temperature.
50%
| 10 degrees C
151
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
152
Autotransformer Ballast is also called a 'lag autotransformer ballast'. TRUE or FALSE?
True
153
Autotransformer Ballast is larger and more expensive than the simple reactor Ballast? TRUE or FALSE?
True
154
The addition of a capacitor in a autotransformer Ballast improves the circuit power factor (PF) to above 90%. TRUE or FALSE?
True
155
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%
156
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
157
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%
158
The capacitor is in series with the bulb in the auto-regulator Ballast. TRUE or FALSE?
True
159
The most common Ballast for Metal-Halide lamps?
Auto-regulator Ballast
160
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
161
The Regulator Ballast is larger and more expensive than the other types? TRUE or FALSE?
True
162
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
163
Do not install High-Pressure Sodium ballasts too far from the fixture because the starting spike attenuates (increases) with distance. TRUE or False?
True
164
The secondary coil of the induction system is represented by the ______ and Mercury Vapour j dude the lamp bulb.
Low-Pressure gas
165
The purpose of a protective device is to open the circuit before any damage can be done to the ______ and ______.
Conductor
| Equipment
166
Fuses provide over current protection by opening the circuit. TRUE or FALSE?
True
167
What is meant by the term 'Overload'?
A moderate increase in current beyond normal rated current value
168
Typical values of overload currents may range as high as ___ times the normal current.
6 times
169
Fuses and Circuit Breakers provide open circuit protection? TRUE or FALSE?
False, they open the circuit.
170
What is meant by the term 'Over current'?
A sharp, extreme rise in current well above normal current rating caused by a short-circuit.
171
An overcurrent may range from ___ times to many hundred times the normal current rating.
Six times
172
Within a few thousandths of a second, a short circuit can become hundreds of times larger than normal operating current. TRUE or FALSE?
True
173
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.
174
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.
175
What is meant by the term 'Ground Fault'?
Another form of short-circuit. It is a short-circuit to ground.
176
Two main benefits of ground fault protective devices?
Protects against fire damage
| Protects human life
177
Arc Fault Circuit Interrupters (AFCI) protect against what?
Protects against unwanted arcing, reacts to irradiated, in-normal arcs
178
GFCIs are designed to protect against ______ while AFCIs are primarily designed to protect against ______.
```
GFCIs = Electrical shock
AFCIs = Arcing and/or fire
```
179
A standard code fuse has a Current Interrupting Rating of ___ Amps.
10,000 Amps
180
3 things to check for when using a fuse
Current rating
Voltage rating
Interrupting rating
181
A high rupture capacity fuse (HRC) has a interrupting rating of ____ Amps.
200,000 Amps
182
Standard Circuit Breakers have a interrupting rating of ___ Amps.
10,000 Amps
183
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
184
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
185
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.
186
I_p is the amount of current let through before the fuse is open (let through current). TRUE or FALSE?
True
187
The usual method of protecting a circuit and equipment is to use a high-speed, specially constructed fuse called _______.
HRC fuse
| High Rupturing Capacity
188
4 critical factors before selecting a protective device
Voltage rating
Current rating
Interrupting rating
Time-current characteristics
189
______ 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
190
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.
191
The maximum short-circuit current an overcurrent protective device can safely interrupt without damaging itself is referred to as?
Interrupting rating
192
Time-delay fuses must be marked with the letter ___.
D
(FRN100) is a time-delay fuse
193
Non-time-delay fuses must be marked with the letter ___.
P
| KTN100) is a non-time-delay fuse
(Low-melting point
194
Generally, the more severe the fault (the higher the fault Current), the _____ the fuse responds.
Faster
195
To minimize inconvenience, it is better if the fuse closest to the fault in the circuit opens first. TRUE or FALSE?
True
196
KTN-R100 is a time-delay or non-time-delay fuse?
Non-time-delay fuse
197
FRN-R100 is a time-delay or non-time-delay fuse?
Time-delay fuse
198
What is meant by the term 'Inverse time-current characteristic'?
The higher the current, the quicker the fuse opens.
199
A fuse is a simple device that protects the _____ of a circuit.
Conductor
200
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
201
Two general categories of fuses?
Plug fuses
| Cartridge fuses
202
The plug fuse is sometimes called the ______.
Screw-base or Edison-base fuse
203
The maximum rating of any fuse is ___ Amps.
30 Amps
204
The knife type fuse is larger than the ferrule contact fuse? TRUE or FALSE?
True
205
Max Volts/Amps rating for Ferrule contact fuse?
600 Volts
| 60 Amps
206
Max Volts/Amps rating for a knife blade fuse?
600 Volts
| 600 Amps
207
A rejection ring must be placed in the fuse holder before this fuse can be inserted into the panelboard.
Type C fuse
208
A rejection adapter must be installed in the standard fuse holder before this fuse can be inserted.
Type S fuse
209
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
210
The metal link of a fuse is made up of ______.
Zinc alloy
211
All renewable fuses are non-time-delay. TRUE or FALSE?
True
212
What does it mean to 'spike a fuse'?
Installing a larger link, or more than one link, in the fuse than necessary.
213
Restrictive segment veins to melt at ___ degrees C for Zinc.
460 degrees C
214
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
215
A time-delay fuse is sometimes referred to as a ______ fuse.
Dual element fuse
216
Almost all standard fuses have a an interrupting capacity rating of ____ Amps.
10,000 Amps
217
Type P fuses have a low melting point and an interrupting capacity rating of _____ Amps.
50,000 Amps
218
HRC fuses do not deteriorate. They have moisture m-proof fibreglass or ceramic barrels, filled with high-quality ______ sand for arc-quenching.
Silica sand
219
HRC fuses are interchangeable/not interchangeable?
NOT interchangeable, they are designed in such a way that other fuses will not fit into their holders.
220
HRCI fuse provides protection from both overloads and short-circuits in cables and equipment. TRUE or FALSE?
True
221
The HRCII fuse gives short-circuit protection only. TRUE or FALSE?
True
222
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
223
Class R fuse, Ferrule has a Amperage rating up to ___ Amps.
60 Amps
224
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
225
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
226
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
227
Class CA
Maximum peak let-through current of 8000 Amps
(The level of fault Current reached before the fuse opens)
Non-interchangeable
228
What is meant by the term 'let-through current'?
The level of fault current reached before the fuse opens
229
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*
230
The Canadian Electrical Code requires that all Circuit Breakers be trip _____.
Trip-free
231
Function of a circuit breaker?
Protects connected apparatus against overloads and short circuits.
232
4 main types of moulded-case Circuit Breakers?
Thermal
Thermal-magnetic
Magnetic
Solid state
233
One of the greatest advantages of the circuit breaker is that it is _____.
Resettable
234
Many Circuit Breakers have two trip elements
Thermal trip
| Magnetic trip
235
(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
236
Magnetic-only breaker only responds to _____.
Over current
CSA calls this breaker an 'instantaneous trip circuit interrupter'
Has no thermal trip element
237
Magnetic-only circuit breaker provides ______ protection, but no protection from _____.
Short-circuit protection
| Overload
238
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.
