TB 8 - Electrical Hazards Flashcards
(196 cards)
1
Q
According to NIOSH, electrical accidents in the US account for over how many deaths a year?
A
700 deaths
2
Q
According to OSHA, statistics indicate that electrocution accounts for what percentage of worker deaths annually?
A
12%
3
Q
According to NIOSH statistics that over the last 20 years, electrocutions to first responders have resulted in more than how many deaths in the service?
A
More than 25 deaths
4
Q
The LAFD resources respond to over how many electrocutions, wires down and other electrical emergencies annually?
A
3000
5
Q
Electricity is one of the most basic and versatile forms of what?
A
Energy
6
Q
Electricity is associated with electric charge, a property of certain elementary particles such as what?
A
Electrons and protons
7
Q
Electric charged can be stationary is in what?
A
Static electricity
8
Q
Electric charged can be moving as in what?
A
Electric current
9
Q
What is amps?
A
Current flow of electron flow
10
Q
Current flows from points of high voltage to points of low voltage on the surface of a conductor and is measured in what?
A
Amperes
11
Q
Quantity of electricity is expressed in amperes (amps) and conversely water is measured in what?
A
GPM
12
Q
What are volts?
A
Difference in electrical potential between 2 points in a circuit
13
Q
Volts are the what behind current flow through a circuit?
A
Push or pressure
14
Q
Electrical pressure is measured in what?
A
Volts
15
Q
The measure of 1000 volts, a measure commonly used be LADWP and the electricity provider industry is expressed in what?
A
Kilovolts
16
Q
What is OHMs?
A
Resistance determines how much current will flow through a component
17
Q
What are resistors used to control?
A
Voltage and current levels
18
Q
Electrical resistance is measured in what expression?
A
OHMs
19
Q
OHMs law defines relationships between what?
A
Power (watts)
Voltage (volt)
Current (amps)
Resistance (OHMs)
20
Q
Amps x volts equals what?
A
Watts
21
Q
Watts x volts equals what?
A
Amps
22
Q
Watts x amps equals what?
A
Volts
23
Q
What is considered to be extremely high voltage (usually transmission voltage)?
A
In excess of 60,000 volts
24
Q
What is considered to be high voltage (found in customer distribution system)?
A
600 - 59,999 volts
25
What else is high voltage referred to as?
Primary circuit voltage or “primaries”
26
In the LADWP system, primary distribution lines are usually what voltage?
4.8 kilovolts
27
What is considered to be low voltage?
Below 600 volts
28
What else is low voltage referred to as?
Secondary circuit voltage or “secondary”
29
Electricity will only yield its pressure once it has found what?
Earth (ground)
30
For electricity fire hydraulics what would be the conductor?
Hose
31
For electricity fire hydraulics what would be current?
Water
32
For electricity fire hydraulics what would be voltage?
Pressure
33
For electricity fire hydraulics what would be amperes?
GPM
34
For electricity fire hydraulics what would be OHMs?
Friction loss
35
Getting electricity to the consumer can be broken down into 3 systems, what are they?
Generation
Transmission
Distribution system
36
The LADWP system is comprised of how many transformers?
Over 50,000
37
The LADWP system is comprised of how many poles?
Over 250,000
38
The LADWP system is comprised of how many sub structures and switches installed?
1000s
39
Where does the electrical energy transformation process originate and where a complete circuit starts?
Power generation plant
40
What uses mechanical energy, such as water pouring through a dam or the motion of a turbine driven by stream to produce electricity?
Generators
41
Generators create electricity by using other forms of energy to turn the generator such as?
Fossil fuel steam plants
Hydroelectric dams
Nuclear power plants
42
Generation facilities generate electricity between what voltage?
4,000 - 20,000 volts
43
What takes the electricity from the generation plant and begin the flow of current over the long distances needed to carry it over transmission lines?
Switchyards
45
In the switching facility transformers utilize their own magnetic fields by lowering amps while proportionately raising the voltage sometimes to over 1 million volts, these are called what kind of transformers?
Step up transformers
46
What are used to carry the electricity from generation stations in a system of wires that carry electricity to the grid and used to carry voltage long distances to distribution stations?
Transmission lines
47
Most common transmission lines in LA are overhead transmission lines which are also called what?
High voltage or high tension wires
48
Voltages on transmission lines range from what voltage?
69 kv - 1000 kv
49
Most of the transmission lines coming into LA are what voltage?
230 kv
50
All voltages above 69 kv are referred to as what?
Transmission voltage
51
The structures that support transmission lines are usually what type of towers?
Steel towers
52
Strings of insulators in transmission towers can range from how many feet long depending on the voltage they are trying to hold back from contacting the towers?
3 - 20 feet long
53
LADWP also has a number of transmission lines with voltages of by?
138 kv or 230 kv
54
What are located mainly in most congested areas and are used for touring bulk power around the city?
Underground transmission lines
55
The component of the electric system that delivers electrical energy to the consumer of residence consist of what?
Distribution stations
| Distribution lines
56
The what can be described as a group of electric stations, high and low voltage power lines and surface and underground transformers located throughout the city?
Distribution system
57
The distribution system works by stepping down the voltage while proportionately stepping up what by using transformers?
Amps
58
The voltage is stepped down how many times in the distribution system before it is delivered to most consumers?
3 times
59
Substations that utilize transformers to change high voltage into lower voltage begins where?
At receiving stations
60
Overhead distribution system consists of wires mounted on what which is the most common type in LA?
Steel or wood mounted poles
61
The LADWP has how many receiving stations?
21 receiving stations
62
The receiving stations receive electricity transmission voltages (138 kv - 500 kv) and step the voltage down to what which is referred to as sub transmission?
34.5 kv
63
There are over how many distribution stations where the electricity is received at 34.5 kv?
150
64
The distribution stations step down the 34.5 kv to what voltage?
4.8 kv
65
The distribution lines carry electricity from distribution systems to where which require low voltage electricity?
Homes
Offices
Factories
66
What lines run from a distribution station to the neighborhood that it feeds?
4.8 kv primary lines
67
Each primary line has an average of how many consumers?
750
68
The LADWP has over how many primary circuits in the city?
1500
69
Each primary circuit has field switches and may be located where?
On poles
| In power vaults under the street
70
Large commercials or industrial consumers such as hospitals, malls, high rise buildings, metro rail and large complexes are connected at what kv?
34.5 kv
71
Transformers are designed to reduce voltage in the system to what?
A voltage usable by the consumer
72
What allows electricity to be efficiently transmitted over long distances by changing electricity from low voltage to high voltage?
Transformers
73
A what is a type of electronic component which passively acts as a form of conductor?
A capacitor
74
What has been known to retain a deadly electrical charge even weeks after power has been removed from the circuit?
High voltage capacitors
75
What are the most common distribution transformers?
Pole mounted transformers
76
Pole mounted transformers are installed on the 4.8 kv circuits to step the voltage down to what for most residential consumers?
120/240 volts
77
Pad mounted transformers are mounted above ground on concrete bases located where?
Parking lots of small and medium sized businesses
Front yard of some residences
78
Underground electrical wires are better insulated and the cable is often larger, true or false?
True
79
Underground lines can be found in several configurations such as?
Underground
Subsurface
Direct buried
80
Underground lines can be found in conduits or ducts and are identified by warning signs labeled what?
UG (underground)
81
Electrical distribution lines placed directly in the ground are designated what?
DB (direct buried)
82
A what is a material that allows an electric current to flow through them easily?
Conductor
83
What are good conductors?
Humans and most metals
84
A conductor can be what and is most commonly what?
Wire (most common)
Cable
Rod
85
Can the voltage of a conductor be determined by the conductors size?
No
86
Insulators are most commonly made of what which prevent flow of electricity?
Glass or porcelain
87
Many commercial and industrial installations have service conductors of what voltage?
34,500 volts
88
There are several types of service connections: single, double, or triple wire, which is the most common wire method and what is it called?
Triplex
89
What are the 3 ways you can determine high voltage?
High voltage signs on cross arms
Size and shape of insulator
Distance between conductors
90
The human body is an excellent conductor of electricity, electrical shock occurs when current passes through what?
The body
91
The degree of shock and resulting injuries depends on the amount of current and the length of what the current phases through the body?
Time
92
What are the 4 main types of electrical injuries?
Electrocution (death by electrical shock)
Electrical shock
Burns
Falls
93
The severity of injury from electrical shock depends on what?
Amount of electrical current and length of time the current passes through the body
94
How many amps of electricity going through the body and for how long is enough to cause death?
1/10 of an amp for 2 seconds
95
The amount of internal current a person can withstand and still be able to control the muscles of the arm and hand can be less than how many milliamps?
10 milliamps (mA)
96
Currents above this many milliamps can paralyze or “freeze” muscles?
Above 10 milliamps (mA)
97
People have stopped breathing when shocked with currents from voltages as low as what voltage?
49 volts
98
Currents greater than what milliamp may cause ventricular fibrillation (very rapid, ineffective heartbeat)?
75 milliamps
99
When a person goes into ventricular fibrillation, this condition will cause death within how long unless a defibrillator or AED is used to save victim?
Few minutes
100
For every minute the defibrillation is delayed, the patient sustains a what percentage reduction in their chances of survival?
10%
101
Heart paralysis occurs at what amperage?
4 amps
102
Tissue is burned with currents greater than how many amps?
5 amps
103
People with less muscle tissue are typically affected at lower or higher current levels?
Lower
104
At 600 volts, the current through the body may be as great as how many amps, causing damage to internal organs such as the heart?
4 amps
105
A longer shock last how many seconds could be fatal if the level of current is high enough to cause the heart to go into ventricular fibrillation?
A few seconds
106
A power drill used how many more times of current as it takes to cause death?
30 times
107
How many milliamps to cause a faint tingle?
1 milliamp
108
Cardiac arrest and server burns occur and death is probable at how many amps?
10 amps
109
What is the lowest overcurrent at which a typical fuse or circuit breaker opens a circuit?
15 amps
110
Greater voltages produce greater what?
Currents
111
The lower the resistance (or impedance in AC circuits), the greater the what will be?
Current
112
Dry skin may have a resistance of how many OHMs or more?
100,000
113
Wet skin may have a resistance of only how many OHMs?
1,000
114
Wet conditions or broken skin will drastically reduce or increase resistance?
Reduce
115
What is the most common shock-related injury?
Burns
116
Ultimately, the danger from electrical shock depends on what?
Amount, duration, and path of the shocking current through the body
117
If you cannot get to the circuit breaker to free a victim who is being electrocuted, you should pry the victim from the circuit with what?
Something that does not conduct electricity
118
If a person sustains a lot of bleeding after being shocked, cool the affected area with what and apply dry dressing and pressure over wound?
Saline
119
Firefighters responding to emergencies involving electrical equipment must wear full turn outs including donning what?
Firefighting hood
| Gloves
120
The most important facet of de-energizing a building during an emergency is the decision of what?
Whether to do so
121
What are the 2 main methods to de-energizing a building?
Opening the main switch or breaker switches at electrical panel
Cutting wires utilizing LAFD equipment
122
The main or breaker switch is a what method for de-energizing a building which can also reduce damage to the occupancy?
Practical
123
Responders should be aware of inherent dangers in discontinuing high voltage current, when high-voltage is suddenly disconnected what can occur with a potential of flash injuries resulting?
Arc can occur
124
When shutting down power from the panel or main switch, wear full PPEs, avoid standing in wet area, stand to the side of electrical panel, turn away from panel when disconnecting power to protect upper extremities and do not what?
Reach across body to disconnect power
125
Do not de-energize a structure by pulling what as this can result in arcing and possibly explode?
Electrical meters
126
The cutting of wires by firefighters must be confined to what voltage wires?
Low voltage
127
In an emergency when there is a need to cut high-voltage lines, call MFC and request who to handle high voltage?
LADWP personnel
128
When cutting wires, you should wear full PPEs, protective goggles or facepiece and use what tools?
Mechanical axe and gauntlet gloves
129
When cutting wires, stand on dry object, you should do what when working on a ladder?
Lock in
130
When cutting wires, when possible cut at the loops attached to where, be sure to cut close to the service bracket in order to make all loose ends dead?
The service head
131
When cutting wires do not reach over what?
Charged wires
132
When cutting wires, which conductor do you cut first?
Closest conductor
133
When cutting wires, after cutters are in place, you should do what with your head to protect eyes from flash and sparks?
Turn head
134
If it is necessary to cut at the pole as opposed to the service head, you should cut how many wires at a time before it goes into the triplex?
One wire
135
Do not cut the bare wire in triplex unless there is a danger of what?
It falling or it has become energized
136
The bare wire on the triplex is what kind of wire that should not present a problem?
Ground
137
The mechanical axe and gauntlet gloves must be tested and inspected at what intervals?
Frequent
138
The mechanical axe and gauntlet gloves should be used on what voltage application only?
Low voltage
139
What is voltage gradient?
A decreasing current created when an energized wire is in contact with the earth
140
What is touch potential?
Occurs by contacting a live or energized source such as a downed wire on a car or fence
141
What is step potential?
Occurs when responders or victims create a circuit with feet as they walk across voltage gradient created by electrical source such as downed wires
142
The ground or voltage current results in different levels of voltage as it dissipates electrical voltage through the ground in what fashion?
Circular
143
Is the apparatus insulated from the ground by its rubber tires?
No
144
If there is any chance the apparatus is in contact with a live conductor, do not step off, get above running board cable and what?
Jump off
145
Standards that cover electrical hazards and the use of tools and equipment near energized equipment and conductors are established by what Cal/OSHA, what title code of federal regulations and what NFPA standard?
Title 29 code of federal regulations
| NFPA 70E
146
For voltages 600 or more, Cal/OSHA and NFPA standards require that aerial ladders be operated a minimum clearance of how many feet of power lines and electrical devices?
10 feet
147
LAFD policy states that aerial ladders shall not be placed how close to power lines and electrical devices?
Close proximity
148
Department members shall not work in violation of the 10-foot rule unless participating in what type of attempt?
Actual rescue attempt
149
Aerial ladder placement must allow for ladder?
Sway, rock, and sag around electrical wires
150
Overhead communication cable normally found on the lowest level of a power pole can be energized up to what voltage?
50 volts
151
Any overhead power line shall be considered energized until what personnel verify that the line is not energized and the line is visibly grounded at the work site?
LADWP personnel
152
Any metal part of an aerial ladder that touches high voltage lines energized the apparatus, the safest course of action for the operator is to do what until power is off?
Touch nothing
153
If apparatus does become energized from electrical devices, utilize what radio traffic procedure to notify all personnel of the hazard?
Emergency traffic
154
If apparatus touches a high voltage line, the operator should do what to break contact with power line?
Back equipment away or lower aerial
155
Keep ground ladders at least how many feet from wires?
10 feet
156
For downed wires, spot apparatus and have responding personnel maintain at least how many spans from the affected wire or pole?
1 span (the distance between 2 poles)
157
If the pole is damaged, do not count the damaged pole, for optimum safety spot the apparatus the distance between how many I damaged poles?
2 undamaged poles
158
Falling conductors often create much sparking, what in these systems are designed to kick out and then kick back in automatically?
Circuit breakers
159
Electrical cables and wires are originally installed from a large spool which cause the wire to maintain what and has a tendency to recoil in the direction of how it was wound in the spool?
Memory
160
For overhead transformer fires, it is usually best to protect exposures and clear area from vehicles and pedestrians. Apply water should be avoided as it can cause adjacent wires to what?
Fall
161
LAFD personnel should extinguish overhead transformer fires after who has de-energized the equipment?
LADWP
162
Streetlight can be fed from conductors carrying how many volts or more?
120-6150 volts
163
For streetlights, LADWP considers them energized with what voltage application at all times?
High voltage
164
Fires in streetlights should be approached in what manner by protecting exposures, removing bystanders and notifying LADWP?
Defensive
165
Is water by nature a good conductor?
No
166
Factors that increase the conductivity of water are what?
Dissolved minerals and impurities in water
167
Where possible, extinguish small electrical fires with what?
Dry chemical or CO2 extinguishers
168
When using hoselines around electrical equipment which pattern should be used due to the air spaces between the drops of water in the stream limiting electrical conductance?
Fog stream
169
What is the 30/33/100 rule when using hose streams around high voltage?
30-degree fog pattern
33 feet from energized source
Minimum of 100 psi pumped to nozzle (reduce conductivity)
170
LADWP recommenced not approaching a high voltage source closer than what length so that a fall forward would not cause direct body contact?
Ones body length
171
The clearly identified method to assure that fire personnel and other responders do not enter life hazard zones includes the use of a minimum of how many horizontal strands of barrier tape (fire line tape) between what inches?
3 strands, 1 inch and 3 inch
172
Occupants trapped in a vehicle by energized wires should remain where until power is de-energized?
Remain in their vehicle
173
The trapped occupants of a vehicle may drive the vehicle clear of wires, the vehicle should be driven clear of the wires by at least how many feet?
35 feet
174
What are the 2 methods that can be used from removing oneself from an energized vehicle without touching it?
Jump or leap, keep feet together while taking small hops from car
Jump and shuffle feet together (heels not toes)
175
Occupants should be instructed to jump from the vehicle from which door?
Farthest from point at which wire is contacting vehicle
176
When responding to rescues on transmission line towers, if the victim is alive use what to instruct him not to move since it is safest for him to remain in place?
Loudspeaker
177
It is possible for LADWP to de-energize transmission lines in usually how many minutes?
5-10 minutes
178
A charge of static electricity capable of jumping how many inches may build up in a persons body when climbing a transmission tower?
2-3 inches
179
While fighting wild land fires, maintain a safe distance from transmission towers of a minimum of how many feet?
35 feet
180
While fighting wild land fires, maintain a clearance of a minimum of how many feet beyond the outermost wire of electrical transmission lines?
100 feet
181
While fighting wild land fires, never direct hose streams into heavy plumes of smoke within how many feet of high voltage wires?
100 feet
182
In many areas of LA, LADWP has installed what instead of overhead wires?
Underground electrical cables and transformer vaults
183
What is the explosive range for carbon monoxide (percentage)?
12.5% - 74%
184
Never put water into a vault or down a manhole, use only what when requested to do so by a qualified LADWP representative?
Non-conducting extinguishers
185
Always locate the nearest manhole covers in how many directions from the involved vault or manhole cover due to nearby manhole covers “blowing” if they are connected to the same shaft?
All 4 directions
186
Manhole covers often weigh 300 pounds and have been blown how high in the air and a distance of how many feet?
75 feet in the air, distance of 125 feet
187
Do not enter a vault or manhole without meeting all mandated what?
Confined space entry procedures
188
DWP line patrolman operate 24 hours a day and can usually reach any area of the City within how many minutes?
10 minutes
189
All electrical service within LA is LADWP with the exception of some transmission lines being serviced by who?
Edison company
190
The LADWP tests gauntlet gloves up to what voltage every 60 days?
10,000 volts
191
Do not cut 2 or more triplex cables at the same time because it will cause what destroying the blades of the mechanical axe and may cause injury?
Short circuit
192
In some locations there is a what cover under the top manhole cover?
Second inner watertight cover
193
A square manhole indicates what kind of vault?
Transformer vaults
194
What is similar to a switch panel, it is the fuse between the main line and transformer. If the transformer catches fire and “shorts out” this fuse should cut off the electrical current?
Oil fuse cutouts
195
The main fire hazard within electrical vaults lies in the cooling oil used in the transformers, which has a flash point below what degree?
300 degrees
196
High voltage cables in vaults are up to how many volts?
230,000 volts
197
The high voltage cables in the vaults may be located close to the floor inside a conduit containing what psi oil pressure?
200 psi
