TB 8 Electrical Hazards

Question 1

AMPS

Answer 1

Current flow, electrical flow, flows from high voltage to low voltage

Question 2

VOLTS

Answer 2

Pressure behind current flow, difference in electrical potential between two points

Question 3

KILOVOLTS

Answer 3

Measure of 1,000 volts. Commonly used by LADWP

Question 4

OHMS

Answer 4

Measurement of resistance, resistance determines how much current will flow through a component

Question 5

OHM’S LAW

Answer 5

Relationship between power (WATTS), voltage (VOLTS), and current (AMPS), and resistance (OHM”S)

Question 6

Low voltage?

Answer 6

Usually below 600 volts

Question 7

High voltage?

Answer 7

600 to 59,999 volts
Customer distribution system
“primaries”
LADWP system 4.8kv

Question 8

Extremely high voltage?

Answer 8

Excess of 60,000 volts

usually transmission voltage

Question 9

Facilities generate electricity between?

Answer 9

4,000 and 20,000 volts

Question 10

Transmission line voltage ranges from?

Answer 10

69kv to over 100kv

Question 11

Most transmission lines coming into LA are what voltage?

Answer 11

230kv

Question 12

Transmission insulators can range from?

Answer 12

3 to 20 feet long

Question 13

LADWP has some transmission lines at what voltage?

Answer 13

138kv to 230kv

Question 14

LADWP receiving stations that receive electricity at 138kv to 500kv and step down to what voltage?

Answer 14

34.5kv (referred to as sub-transmission)

Question 15

What are transformers designed to do?

Answer 15

Reduce the voltage in the system to a capacity usable by the consumer

Question 16

High-Voltage capacitors have been known to retain a deadly charge for how long?

Answer 16

Weeks after power has been shut down

Question 17

Overhead and Pad Mounted Transformers are installed on the 4.8kv circuits and step the voltage down to what?

Answer 17

120/240 volts

Question 18

What are the four main types of electrical injuries?

Answer 18

Electrocution
Electrical Shock
Electrical Burn
Electrical Fall

Question 19

For every minute that defibrillation is delayed, the patient sustains what percentage reduction in their chances for survival?

Answer 19

10%

Question 20

Tissue is burned with currents greater than how many amps?

Answer 20

5 amps

Question 21

Heart paralysis and damage to organs occurs with how many amps?

Answer 21

4 amps

Question 22

What are the two main methods for de-energizing a building?

Answer 22

Main breaker

Cutting wires utilizing LAFD equipment

Question 23

Pulling meters to de-energize a building may cause what to happen?

Answer 23

Arching

Question 24

For voltages of 600 or more, Cal/OSHA and NFPA standards require that aerial ladders be operated at a minimum clearance of?

Answer 24

10 feet of power lines and electrical hazards

Question 25

Streetlights can be fed from conductors carrying how many volts?

Answer 25

120-6150 volts

Question 26

What is the 30/33/100 rule as it applies to using a hose stream on an electrical fire?

Answer 26

30 degree fog pattern
33 feet (minimum) from energized source
100psi (minimum) pumped to nozzle

Question 27

What is the proper method to clearly identify a LIFE HAZARD ZONE?

Answer 27

Three horizontal strands of barrier tape
“DO NOT ENTER” OR “DO NOT CROSS”
Fireline tape may be used
Flagging tape may be used (1”and 3”)

Question 28

Vehicle should be driven clear of wires how many feet if safe to do so?

Answer 28

35 feet

Question 29

LADWP can de-energize the lines for a power line rescue in how many minutes?

Answer 29

5 to 10 minutes

Question 30

OPERATIONS NEAR TRANSMISSION LINES: Maintain a distance of how many feet from towers?

Answer 30

Minimum of 35 feet

Question 31

Maintain a clearance of how many feet beyond the outermost wire of electrical transmission lines?

Answer 31

100 feet (minimum)

Question 32

Never direct hose streams into heavy plumes of smoke within how many feet of high-voltage lines?

Answer 32

100 feet

Question 33

What is the explosive range for Carbon Monoxide (co)?

Answer 33

12.5 to 74%

Question 34

Always locate manholes in what directions from the involved vault?

Answer 34

All four directions

Question 35

The IC SHALL ensure that all occupancies?

Answer 35

Inspected for hazards

Question 36

Manhole covers often weigh?

Answer 36

300 pounds

Question 37

Manhole covers can be blown how high and at what distance?

Answer 37

75 feet and 125 feet

Question 38

What is the main fire hazard within electrical vaults?

Answer 38

Cooling oil has a flash point of 300 degrees

Question 39

UNDERGROUND VAULT: High-Voltage cables up to how many volts?

Answer 39

230,000 volts (may be located close to floor inside conduit)