Electrical Flashcards
1
Q
Which slots in a receptacle are hot and neutral
A
Wide= neutral
Narrow= hot
2
Q
How do you cut power
A
Switching off main breaker or removing fuse
3
Q
Panel clearances
A
78” headroom
36” free space
30” across face of panel
4
Q
How many wires in an overhead service (service drop)
A
3 wires- 2 hots and a neutral
2 wires- outdated
5
Q
What material is a service neutral
A
Stranded aluminum with a steel core
6
Q
Overhead servicewires must be how high
A
12’ above driveways
10’ above pedestrian walkways
18’ above swimming pools
3’ above operable windows
7
Q
Describe in order from the service neutral primary to meter
A
Neutral primary
(Ground)
Transformer
Service drop
Splice point
Weatherhead
Meter panel
8
Q
What can also serve as a service neutral
A
Messenger cable. (Bare steel wire)
9
Q
Hots from meter attach to what on main breaker
A
Lugs or terminals
10
Q
Neutral and ground bus must be
A
Connected together by the bonding jumper in the main panel only. In all other locations, they must be isolated from each other
11
Q
What happens when a circuit is overloaded
A
Breakers trip or a fuse melts
12
Q
What is the primary overcurrent protection
A
Main breakers or main disconnects
13
Q
Photovoltaic
A
Solar systems. (Main breaker will not always de-energize panel)
14
Q
What is a meter base and main breaker in a single box called
A
Meter/main
15
Q
What will you see on a fuse if a circuit is overloaded
A
Filament will be separated
16
Q
What are screw in and slide in fuses called
A
Screw-in = Edison type
Slide in= cartridge
17
Q
Fuse with blackened interior=
A
Short circuit
18
Q
2 wire service voltage
3 wire service voltage
A
2= 120 only
3= 240/120
19
Q
Frequently blown fuses =
A
Overloaded circuit or short circuit
20
Q
What should you do if a properly rated fuse blows when an appliance starts
A
Replace with a time delay fuse of the same rating
21
Q
What are the hazards with double tapping breakers
A
Arcing and wires could melt instead of breaker tripping if there were an overloaded or short circuit
22
Q
What hazards do missing cable clamps pose
A
Wires could be scored and pests could enter
23
Q
What should cables be protected with when entering panels
A
Bushings/ strain relief clamps
24
Q
What is the inside cover of a panel that protects from energized components called
A
Dead front
25
Many panels have a rating sheet listing
Compatible breaker brands and types
26
When 2 breakers are paired to protect a 240 volt circuit, they should be
Mechanically protected
27
What are used to protect multiwire branch circuits
Handle ties
28
Installing what in older panels can allow for installation of porcelain fuses
Type S fuses
29
What is “pennying” a fuse
When shit birds unscrew fuses and insert a penny then installs a fuse so current bypasses the fuse
30
What can grounding electrodes be
Metal underground water pipes
Ground rods
Ufer electrodes
31
Cold water pipes and gas pipes must be
Bonded to the grounding bus panel
32
Why are neutrals most likely to show signs of overheating
Because 2 hot wires can share a single neutral
33
Melted wire insulation is often caused by
Overfusing or arcing from loose connections
34
Double tapping wires is also called
Double tugging
35
Describe multiwire circuits
Pairs of 120 that share a neutral
Pairs of hot wires must originate from different poles
36
Why must multiwire circuits originate from different poles
To prevent overloading the neutral (240 potential between them)
37
Why are fused neutrals unsafe
Loose or missing neutral could make a circuit appear dead when it is not
38
Where should service panel ground and neutral wires be bonded together
In main panel. Not in subpenels or anywhere downstream. Neutral should be isolated to prevent current from being carried onto grounding wires and components
39
Fused neutrals are installed on both hot and neutral wires in some old panels. Why is this not safe
Because if a neutral fuse blows, the circuit will appear dead
40
In the main panel ground wires are attached to a neutral/ground busbar, which is bonded to the metal panel housing via a
Main bonding jumper
41
When metal water piping functions as a service ground what should you look for
Any sections of metal pipe replaced with plastic pipe. Grounding system should be updated
42
What should be installed when a dielectric union is used
Bonding jumper should jump around it if that is the system ground
43
What is the dielectric union
Attachment that prevents copper from corroding steel
44
What does GES stand for and what is its main function
Grounding electrode system. Low impedance path to ground
45
Describe Gecs
Number six AWG attached to 8 foot rod
46
What is a ufer
Concrete encased grounding electrode
47
Ground wires between the main panel and ground rod must be mechanically protected by
Being secured to the siding/running through conduit
48
What is NM cable
Non-metallic sheathing or Romex
49
Cables that run through walls and studs should be quarter inch away from face or
Have a metal nail plates
50
Do single gang plastic boxes require strain relief cable clips
No
51
Small gauge aluminum wire can be a fire hazard unless it is
Connected to a copper wire with a COPALUM connecter or terminated to CO/AL rated lights, etc.
52
What is the hazard of an aluminum wire connected to a copper only device
Metals will expand and contract at different rates when underload and that cause loose connections and overheating
53
Describe knob and tube wiring
Splice is wrapped with electrical friction tape and supported by porcelain knobs
Lacks an equipment ground
Run completely on insulators
Copper coated with tin
54
What is the hazardous method of temporary wiring for a permanent installations called
Lamp cord/ZIP Cord wiring
55
Lighting loads are calculated at how many watts per square foot
Three watts per square foot
Or 1 15 amp circuit per square foot
56
Roughly how many outlets per 15 amp circuit and how many for 20 amp
Nine outlets for 15 amp and 10 per 20 amp
57
Where should GFCI protection be
Near all water basins, bathroom, kitchen counters, outdoors, unfinished basements, garages
58
Describe AFCI protection
Detects arcs from damaged insulation by detecting erratic sine waves
Required in living spaces in new construction and in smoke alarms
59
Knob and tube wiring may cause these to trip
AFCI’s
60
Describe bathroom circuits
20 amp circuit for receptacles in more than one bathroom or lights, etc. in one
Heating fans on their own circuit
GFCI protected
61
Requirements for kitchen circuits
At least 2 20 amp small appliance circuits for countertops
Receptacles every 4 feet
Counters 12 inch wide must have a receptacle
GFCI protected
62
 These lightbulbs should not be used as closet lights
Bare incandescent bulbs
63
Code requires these outlets to be labelled
Ungrounded three hole outlets
64
Receptacles narrow prong and wide prong are
Hot is narrow and neutral is wide
65
Describe GFCI receptacles line
Incoming power from breaker box. Line terminal protects the receptacle location
66
Describe receptacles load
Outgoing power that travels down to the next outlet
67
What happens with a line/load reversal in a GFCI
GFCI test will work downstream but not at particular outlet
68
In modern construction, Electrical outlets are not allowed above
Baseboard heaters
69
Receptacles in damp/wet locations must have
Rain tight weatherproof covers
70
Receptacles in garage should be how high and why
18 inches above floor to avoid Sparks and starting a fire
71
These slow down or resist electrical flow
Resistors or insulators
72
Electrical consumption is measured in
Kilowatt hours. 1000 W per hour equals 1 kWh
73
Circuit breakers and fuses are what kind of protection
Overcurrent protection
74
Overhead service is also called
Service drop
75
Underground service is also called
Service laterals
76
Three most common problems with the services
Damage, improper location, moisture
77
Rather than A conduit, some homes have a service entrance
Cable
78
What is the conduit called in the service
Service mast
79
Service entrance conductors have to enter the conduit through a
Weather tight cap
80
Describe an older service box
Switch with the handle located outside, service fuses inside
81
How many disconnect points in a house are acceptable
Six points
82
Clearance for service boxes
5 feet above the floor in 3 feet of clearance in front
83
Where should service boxes not be located
In closet, stairwells, bathrooms, etc.
84
Up until 1960, grounding was only at
The service panel
85
If the system ground is connected downstream of the water meter or water filter what is provided
Jumper wire is provided across the metre or filter to maintain connection if a device is removed
86
List system grounding configurations
Well casing, Wire encased in the concrete footing, metal plate or ring or rod
87
Where should the ground wire, service box and neutral be bonded together
Only at the service box. And not down stream
88
Why are old ceramic fuseholders considered obsolete and unsafe
Exposed terminals lead to shock hazards
89
Is installing a blown fuse on a spare circuit to fill an opening acceptable
Yes
90
Solution to double tapping
Auxiliary panel
91
What is the problem with bonding the ground and neutral downstream of the main panel
May inadvertently turn ground into a current carrying conductor
92
Wrong sized fusing is common, as some fit in the same blocks. What prevents this
Fuse rejecter washers
93
Describe the type C fuses
Screw in or plug fuses. Non-interchangeable
94
Describe type P fuses
Low melting temperature
Used for non-motor loads
95
Describe type D fuses
Time delay for motor starting current
96
What is the danger with poor connections in fuses in breakers
Possible overheating and fires without enough current to trip breakers
97
If there are two circuits on one receptacle, what must the breakers have
Interlocking
98
A GFCI shuts power off when as little as how many amps are leaking
.005
99
What do GFCI’s detect
The amperage difference between LiveWire and return
100
What’s the difference between a GFCI circuit breaker and a GFCI receptacle
GFCI circuit breakers protect the whole circuit. GFCI receptacles protect that outlet in downstream outlets on that circuit
101
What is the most common problem with GFCI is not working
Line/load reversed
102
Where are arc faults commonly found
Where electrical cords are damaged or outlets are properly installed
103
What hazards do AFCI’s and GFCI’s protect from
GFCI’s prevent shock. AFCI prevent fires
104
Pre-1960 installations did not include this in a branch circuit for distribution circuit
Ground wire
105
These need their own dedicated circuits
Fridges and heating systems
106
Name three methods of protection from metal edges in boxes
Bushings, grommets, cable clamps
107
Wiring should be kept in 1 inch Away from
Heating ducts and water piping. Or add insulation
108
These conductors cannot be run as overhead supported wiring
Solid conductors. Stranded conductors are stronger
109
Maximum of how many lights/outlet Per circuit
12
110
Outlets likely to use a hair dryer should be on
Low drawing circuits
111
What are grounded and ungrounded conductor is called
Live wires are called ungrounded. Neutrals are called grounded connecters
112
Describe the knobs and tubes in knob and tube wiring
Ceramic tubes through walls in studs. Ceramic knobs secure it
113
How were connections made in knob and tube wiring
By twisting wires together and soldering and wrapping and rubber
114
Describe how the wires are run in knob and tube wiring
Hot and neutral or run separately. No ground wire
115
Why is knob and tube wiring commonly replaced
Rubber insulation with a cloth sheathing – breakdown
116
Common problems of knob and tube wiring
Poor connections made after original installation
Two fuses on a single circuit
117
Why is knob and tube wiring dangerous
Fuses are at the beginning and end. Replace panel
118
Why is aluminum wire more susceptible to having loose connections
Higher coefficient of thermal expansion than copper (expands more)
119
What is another term for loose connections caused by expansion and contraction of metals
Creeping
120
Are the oxides that form on aluminum and copper good or bad
Copper is good aluminum is bad
121
What are needed for aluminum to Copper connections
Special devices or connecters that are rated CO/AL
122
These outlets plug-in 2 appliances
Duplex receptacles
123
Describe polarized receptacles
Small is live and larger slot is neutral
124
Other names for outlets with holes instead of screws
Bayonet
Dagger
Push in type
125
Describe tamper resistant outlets
Internal mechanism blocks openings until both prongs are inserted. Child proof
126
What can improve safety for an ungrounded system but is not a replacement for a system ground
GFCI’s
127
T-shaped neutral slots are for
20 Amp receptacles
128
Outlet should not be facing up on horizontal surfaces or be horizontal unless
They are a specific type due to moisture hazard possibilities
129
What happens with an appliance if the receptacle it is plugged into has reversed polarity
Can operate improperly or have it’s grounding made ineffective
130
Recessed lighting fixtures should not be installed in areas where
Insulation will blanket
131
Describe IC light fixtures
Recessed light fixtures that can contact insulation.
(Insulation contact or insulated ceiling)
132
Where should heat lamps in the ceiling be located
Beyond the swing of doors
133
Why should old porcelain fixtures without boxes be replaced
Live connections are exposed
134
Incandescent bulbs in closets should be
Enclosed
135
Three way switches are how many switches that control how many lights
Two switches that control one set of lights
136
How many wires for three way switches
Three wire cable plus ground
137
What is the wiring between the two switches on a three-way called
The traveller
138
The switches are considered unsafe
Old pushbutton switches
139
What kind of junction boxes are required on building exteriors and damp locations
Special water resistant junction boxes
140
What should an outdoor component of an AC system have a weathertight box for servicing
Electric disconnect
141
Describe a garbage disposal cord
18 inches minimum and 36 inches maximum with a drip loop and armoured cable
142
What should be within sight of the furnace/boiler
Disconnect switch
143
Service size is determined by
Calculated Load and minimum service size
144
What is calculated load
After demand factors are applied
145
Nicking or ringing aluminum conductors does what
Reduces ampacity they can carry
146
What size most neutral service conductors be
Same size as hot conductors
147
Service neutral carries
Only unbalanced load
148
Service new show must be capable of carrying
Fault current to open main fuse/breaker
149
Service mast conduit must be how big in diameter
2.5 inches
150
Uninsulated service neutral is split for
Return back to transformer and support wire to mast
151
Breaker panel is also called
Load centre
152
Service ground goes from
Line to ground to electrode to panel inside. No ground in mast. Neutral is grounded at the pole and the house
153
Do you have to test every receptacle
No. Just a representative amount. But every the GFCI should be tested
154
In reporting amperage and voltage ratings of services, the metre and panel might differ. What should you call the service
The smallest reading of the two
155
What kind of wire is used for appliances
Multistrand aluminum. Single strand or solid branch aluminum must be reported
156
Single strand aluminum is also called
Solid branch
157
Good conductors have more
Free electrons
158
Electron flows from
Negative to positive
159
Ohms law equation
PIE
160
Describe Order where power comes from
Power plant, transmission station, HV transmission lines, power subtition station, transformer drum, home
161
Four wires – three hots plus neutral indicates
Three phase 208 or 240
162
Three wire - two hots plus neutral indicates
120/240
163
What note should you take on service conductors
How many, CO or AL, Where size is it mean disconnect, and if aluminum, confirm NO-OX paste
164
Service conductor size is for 200 A and 100 A
2/0
#4
165
What is a strip footing ground called
Ufer ground
166
What should you see in a service panel for bonding
Main bonding jumper or green ponding screw
167
Which two panels typically have problems
Federal Pacific
VInsco
168
In subpanels what is done with the neutral
Isolated from ground
169
Are splices allowed in panels
Yes. One to two spaces may be allowed
170
Where should bell transformers be
Outside of the panel
171
What do you receptacle boxes in the inside of exterior walls need
Vapour barriers around the box
172
What kind of junction boxes used for lighting
Octagon box
173
Why are AFCI good to use with aluminum wiring
They can also detect faulty connections
174
What kind of bushing should you see in a service panel
A grounding bushing
175
Neutral should Not be bonded to ground at any subpanel. What is this called
Floating neutrals
176
Should a neutral ever go back to a breaker
Yes. Only for GFCI in AFCI breakers
177
There must be a main disconnect if there are more than how many breakers
Six
178
There must be a disconnected the panel is more than how far from a meter
6 feet
179
What is the main panel
First point of disconnect
180
Knob and tube wiring which is the grounded conductor
Neutral
181
When Two hots share a neutral what must be done
Hots must be on separate phases
182
Can an AFC I share a neutral
No
183
How can reversed polarity cause possible overheating
It can cause devices plugged into have constant power. Live wire is bypassing the switch contact
184
What is a wire crimper grounds also called
Buchanan
185
If a two wire system has three prong outlets, will a GFCI protect the circuit
It won’t trip downstream. Only that receptacle. So either use GFCI breakers or replace every receptacle you need to protect
186
What is a possible reason for recessed lighting shutting off intermittently
Bulb maybe too big. Heat sensor in fixture in recessed lighting
187
Some fuse panels need this done before removing cover
Need fuses pulled out
188
What is the neutral on an AFC I breaker called
Pigtail
189
False Ground on tester causes
Neutral and ground terminals are bonded together
appliances (a washing machine might have a path to ground)
190
What happens when The ground and neutral reversed on a receptacle
Outlet will seem OK unless a tester is used
Current will flow through the ground wire
191
Big voltage drop indicates
High resistance. Possibly oxidized aluminum connection
192
Current is described as
Electrical flow per unit of time
193
Voltage is described as
Energy per unit of charge
194
Do GFCI’s protect against over current
No
195
What is an RCBO stand for
Residual current breaker overcurrent
196
Common cause for housefires
Low current Arcing
197
What are fused neutrals
More than one neutral under a screw. Used to be acceptable
198
Should there be a bond screw in a neutral bus bar in a sub panel
No
199
Describe wiring on 3 way switch
2 wire plus ground power source
3 wires plus ground from switches (+ traveller)
Neutral bypasses switches but connects to lights
200
Describe wiring on a light/switch
Two wire plus ground
Neutral bypasses switches but connects to lights
201
if you double voltage what happens with amps and power
Amps will double and power will quadruple. But if your power demand stays the same, amps half
202
Neutral in a three wire circuit carries what and what happens if incorrectly connected
 Only unbalanced current
If connected incorrectly, it must carry the sum of the black and red 
203
The bare wire in the supply cable, connects to what in the panel
An enclosure at each end in the panel. All grounding in these branch circuits depends on these connections.
204
Cables in the attic should be run on top or under insulation
Under
205
Can house wiring be run in cold air ducts
Yes, but not outlet boxes
206
Red cables often mean
240 V or heating
207
Service size is determined by
The minimum of service component ratings
208
These components of an electrical system must be inspected
Service drop, service entrance, branch circuit wiring, grounding
209
What are the two main functions of equipment grounding?
Prevent the outer case for being hot and provides alternate current return, if neutral fails
210
you plug your circuit tester into an outlet that has a washing machine plugged in. Your tester shows the outlet is properly wired and grounded. How could you improve this inspection process?
Unplug the washing machine
211
Special grease on aluminum wires is found on
Stranded wires
212
Is a light above a closet shelf a problem
Fuck I guess so
213
Is overheated neutrals on multiwire branch circuits a problem in knob and tube wiring
No.
214
Abandoned wires should be
Removed. Even though that is a dog shit fucking answer.
215
Why is knob and tube wiring not supposed to be covered with insulation
Made to dissipate heat into free air so this can cause overheating of wires
216
Grounded wires
Ungrounded wires
Grounded = neutral
Ungrounded= hot
217
Service equipment=
Main service disconnect
218
Is the service meter grounded
It is bonded to ground through the grounded neutral wire. Transformer is grounded and main is grounded
219
Can rebar in the foundation be used as ground
Yes
220
Lights that can’t be turned on or off with switch
Possible split receptacles
221
Report the location of these
Main disconnects and sub panels
222
Inspectors aren’t required to inspect
Remote control devices (unless only means)
Alarm systems
Ancillary wiring systems
Measure amperage, voltage, impedance
223
What is a panel called that has a breaker separating sections
Split bus panel
224
Why is neutral isolated, insulated from ground
Path for current to travel to transformer in ground fault
So grounding wires don’t conduct returning neutral current
Neutral current in equipment ground can energize casings
225
How do you determine service size
Service conductor size
Main disconnect rating
Main panel label rating
226
Can a system ground be spliced
Not ideally. Only done with irreversible compression type or by r exothermic welding
227
What should be written on a ground rod
DB- direct burial
228
What size should water pipe/gas pipe be bonded with
Same size as service ground
229
Can conduit bond main and sun panels together
Yes. Grounding bushings are recommended though
230
Type D fuse
Type P
Type S and C
D= time delay (allow more current at start)
P= sensitive to heat build up between fuse and holder
S and C= non interchangeable
231
Types of cables
Nm = non mentallic sheathed
Appliance cable = solid ground wire
MC= armoured cable (bx)
232
Why are service drop wires able to be smaller than the service entrance wires
In free air which helps them cool
Less of a risk if overheated
233
Can line (incoming power) in a main disconnect be bigger than load (power out) going to service panel
No. Auxiliary panels can have smaller wires though
234
Can wires bypass meter and main
Yes. For a flat rate water heater
235
Is 240 single phase
Yes but has 2 poles
236
Possible ways of back feeding into panel
Photovoltaic
Car charger
Back up generator
237
Will you usually see stranded with lower or higher amp carrying
Higher. Usually #12 and #14 will be solid copper
238
Wires should be secured within how far from a box
8-12 inches
239
Tinned copper is also called
Solder dipped copper
240
When do you need a grounding bushing on main
When all knockouts in entry haven’t been removed. And anything larger than 1”
241
In a main panel, can you combine grounds and neutrals on the same bus
Yes
