TB 008 - Electrical Hazards at Fires

Question 1

According to the National Institute for Occupational Safety and Health (NIOSH), electrical accidents in the United States account for over ____ deaths a year and OSHA statistics indicate that electrocution accounts for 12% of worker deaths annually

Answer 1

700

Question 2

NIOSH statistics also document that over the last 20 years, electrocutions to first responders have resulted in more than ___ deaths in the fire service.

Answer 2

25

Question 3

The Los Angeles Fire Department (LAFD) resources respond to over _____ electrocutions, wires down, and other electrical emergencies annually

Answer 3

3000

Question 4

• ______ - Current flow, or electron flow, is what flows on a wire or conductor like water flowing down a river

Answer 4

AMPS

Question 5

• _______ - Electrical pressure is measured in volts, while the comparable term in water hydraulics would be pounds per square inch (psi).

Answer 5

VOLTS

Question 6

• KILOVOLTS- The measure of _____ volts

Answer 6

1000

Question 7

• ______ - The resistance to a flow of water through a hose would be termed friction loss and would be measured in pounds per square inch.

Answer 7

OHMS

Question 8

Watts = amps x volts & VICE VERSA

Answer 8

.

Question 9

• Extremely high voltage: voltages in excess of ________ volts

Answer 9

60,000

Question 10

• High voltage: voltage from ____ volts up to ________ volts

Answer 10

600
59,999

Question 11

In the LADWP system the primary distribution lines are usually ____kv.

Answer 11

4.8

Question 12

• Low Voltage: Usually below ____ volts

Answer 12

600

Question 13

Conductor = ______

Answer 13

Hose

Question 14

Current = ______

Answer 14

Water

Question 15

Voltage = __________

Answer 15

Pressure

Question 16

Amperes = ______

Answer 16

GPM

Question 17

Ohms = _____________

Answer 17

Friction Loss

Question 18

Getting electricity to the consumer can be broken down into __ systems

Answer 18

3

Question 19

Getting electricity to the consumer can be broken down into three systems:
1. ____________
2. ____________
3. ____________

Answer 19

1. Generation
2. Transmission
3. Distribution

Question 20

The LADWP system is comprised of over ________ transformers, over ________ poles and 1000’s of substructures and switches installed over the last 70 years.

Answer 20

50,000
250,000

Question 21

The _____________________ is where the electrical energy transformation process originates and where a complete circuit starts

Answer 21

power generation plant

Question 22

Generation facilities generate electricity between ______ and ________ volts

Answer 22

4000
20,000

Question 23

Voltages on transmission lines range from ___kv to over ______kv

Answer 23

69
1000

Question 24

Most of the transmission lines coming into Los Angeles are ____kv, but many lines are higher than that

Answer 24

230

Question 25

All voltages above ___kv are referred to as transmission voltages

Answer 25

69

Question 26

Strings of insulators on transmission towers can range from __ to ___ feet long depending on the voltage they are trying to hold back from contacting the towers that support them

Answer 26

3 to 20

Question 27

Receiving Station – The LADWP has ___ receiving stations

Answer 27

21

Question 28

Receiving Station – receive the electricity at transmission voltages (____kv to ____kv) and step the voltage down to _____kv, which is referred to as sub-transmission

Answer 28

138kv to 500kv 34.5kv

Question 29

There are over 150 distribution stations where the electricity is received at 34.5kv and stepped down to ____ kv. Known as the primary circuit voltage

Answer 29

4.8

Question 30

High-voltage capacitors have been known to retain a deadly electrical charge even ___________ power has been removed from the circuit

Answer 30

Weeksafter

Question 31

Overhead Transformers - They are installed on the 4.8kv circuits to step the voltage down to ____/____volts for most residential consumers

Answer 31

120/240

Question 32

Underground lines can be found in conduits or ducts and are identified by warning signs labeled ___ (underground). Electrical distribution lines placed directly in the ground are designated direct buried ___

Answer 32

UG DB

Question 33

Insulator – They are most commonly made of _______ or __________

Answer 33

Glass Porcelain

Question 34

Service Connection – The wires that connect the customer or home to the secondary transformer, Many commercial and industrial installations have service conductors of ________ volts

Answer 34

34,500

Question 35

The most effective methods of identifying different voltages are: 1. High voltage signs on the ______ ______. 2. The size and shape of ___________ 3. The distance between ____________

Answer 35

Cross Arm Insulator Conductors

Question 36

_____ of an amp of electricity going through the body for just __ seconds is enough to cause death

Answer 36

1/10 2

Question 37

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 ___ milliamps (mA). Currents above ___ mA can paralyze or “freeze” muscles

Answer 37

10 10

Question 38

People have stopped breathing when shocked with currents from voltages as low as ___ volts

Answer 38

49

Question 39

Usually, it takes about ___ mA of current to cause respiratory paralysis.

Answer 39

30

Question 40

Currents greater than ___ mA may cause ventricular fibrillation

Answer 40

75

Question 41

For every minute that defibrillation is delayed, the patient sustains a ___% reduction in their chances for survival

Answer 41

10

Question 42

Heart paralysis occurs at __ amps, which means the heart does not pump at all. Tissue is burned with currents greater than __ amps

Answer 42

4 5

Question 43

At 600 volts, the current through the body may be as great as __ amps, causing damage to internal organs such as the heart

Answer 43

4

Question 44

Dry skin may have a resistance of _________ ohms or more. Wet skin may have a resistance of only _______ ohms

Answer 44

100,000 1,000

Question 45

Cutting Wires Utilizing LAFD Equipment - The cutting of wires by firefighters must be confined to _____________ wires

Answer 45

Low-Voltage

Question 46

__________ __________: Is a decreasing current created when a energized wire is in contact with the earth

Answer 46

Voltage Gradient

Question 47

_______ ___________: Occurs by contacting a live or energized source

Answer 47

Touch Potential

Question 48

______ ___________: Occurs when responders or victims create a circuit with their feet as they walk over or across a voltage gradient created by an electrical source, such as a downed wire

Answer 48

Step potential

Question 49

For voltages of 600 or more, Cal/OSHA and NFPA standards require that aerial ladders be operated at a minimum clearance of (___) feet of power lines and electrical devices

Answer 49

10

Question 50

Department members shall not work in violation of the 10-foot rule unless participating in an actual rescue attempt, and in those instances the Apparatus Operator shall remain at the __________ to provide for personnel safety and ensure safe operation of the aerial if required

Answer 50

Pedestal

Question 51

Even overhead communication cable normally found on the lowest level of a power pole can be energized with up to ___ volts

Answer 51

50

Question 52

Spot apparatus and have responding personnel maintain at least one span (the distance between __ poles) from the affected wire or pole

Answer 52

2

Question 53

Streetlights can be fed from conductors carrying _____-_____ volts or more

Answer 53

120-6150

Question 54

Where possible, extinguish small electrical fires with ______________ or _______ extinguishers

Answer 54

Dry Chem CO2

Question 55

Utilize the ___/___/____ Rule for using hose streams around high voltage

Answer 55

30/33’/100 psi

Question 56

The LADWP also recommends not approaching a high-voltage source closer than ______ body length, so that a fall forward would not cause direct body contact

Answer 56

Ones

Question 57

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 (__) horizontal strands of barrier tape that state “Do Not Enter” or “Do Not Cross” between __ inch and __ inches

Answer 57

3 1 & 3

Question 58

Occupants trapped in a vehicle - vehicle should be driven clear of the wires by at least ___ feet

Answer 58

35

Question 59

There are two methods that can be used from removing oneself from an energized vehicle: • Jump or leap from the vehicle without touching it, keeping both feet together and taking small _____ from the car. • Jump from the vehicle without touching it and _________ the feet together

Answer 59

Hops Shuffling

Question 60

ELECTRICAL HAZARDS AT WILDLAND FIRES - With heavy smoke present, firefighters should be especially cognizant of remaining at least ____ feet from transmission lines and ___ feet from transmission towers

Answer 60

100 35

Question 61

VAULT/MANHOLE FIRES - The explosive range for carbon monoxide (co) is ____ to ___ percent

Answer 61

12.5 74

Question 62

Manhole covers often weigh ____ pounds and have been blown ___ feet into the air and a distance of ____ feet

Answer 62

300 75 125

Question 63

Do not cut __ or more triplex cables at the same time

Answer 63

2

Question 64

Look for, and note, if there is a _______ manhole, which indicates a transformer vault

Answer 64

Square

Question 65

Remember that the main fire hazard within electrical vaults lies in the cooling oil used in the transformers, which has a flash point below ____F

Answer 65

300

Question 66

UNDERGROUND/ABOVE GROUND VAULTS - High-voltage cables, up to ________ volts, may be located close to the floor inside a conduit containing ____-psi oil pressure

Answer 66

230,000 200

Question 67

There are two main components of the transmission system: • ______ • _____________ ______

Answer 67

• Grids • Transmission lines

Question 68

Cut the _________ conductor first. When cutting, do not touch another conductor or a ground. After cutters are in place, turn head to protect eyes from flash and sparks

Answer 68

Closest

Question 69

DO NOT CLIMB THE TOWER UNTIL ASSURED BY LADWP THAT IT IS SAFE. A charge of static electricity capable of jumping __ or __ inches may build up in a person’s body when climbing a tower

Answer 69

2 3