TB 8 Electrical Hazards Flashcards
AMPS
Current flow, electrical flow, flows from high voltage to low voltage
VOLTS
Pressure behind current flow, difference in electrical potential between two points
KILOVOLTS
Measure of 1,000 volts. Commonly used by LADWP
OHMS
Measurement of resistance, resistance determines how much current will flow through a component
OHM’S LAW
Relationship between power (WATTS), voltage (VOLTS), and current (AMPS), and resistance (OHM”S)
Low voltage?
Usually below 600 volts
High voltage?
600 to 59,999 volts
Customer distribution system
“primaries”
LADWP system 4.8kv
Extremely high voltage?
Excess of 60,000 volts
usually transmission voltage
Facilities generate electricity between?
4,000 and 20,000 volts
Transmission line voltage ranges from?
69kv to over 100kv
Most transmission lines coming into LA are what voltage?
230kv
Transmission insulators can range from?
3 to 20 feet long
LADWP has some transmission lines at what voltage?
138kv to 230kv
LADWP receiving stations that receive electricity at 138kv to 500kv and step down to what voltage?
34.5kv (referred to as sub-transmission)
What are transformers designed to do?
Reduce the voltage in the system to a capacity usable by the consumer
High-Voltage capacitors have been known to retain a deadly charge for how long?
Weeks after power has been shut down
Overhead and Pad Mounted Transformers are installed on the 4.8kv circuits and step the voltage down to what?
120/240 volts
What are the four main types of electrical injuries?
Electrocution
Electrical Shock
Electrical Burn
Electrical Fall
For every minute that defibrillation is delayed, the patient sustains what percentage reduction in their chances for survival?
10%
Tissue is burned with currents greater than how many amps?
5 amps
Heart paralysis and damage to organs occurs with how many amps?
4 amps
What are the two main methods for de-energizing a building?
Main breaker
Cutting wires utilizing LAFD equipment
Pulling meters to de-energize a building may cause what to happen?
Arching
For voltages of 600 or more, Cal/OSHA and NFPA standards require that aerial ladders be operated at a minimum clearance of?
10 feet of power lines and electrical hazards
Streetlights can be fed from conductors carrying how many volts?
120-6150 volts
What is the 30/33/100 rule as it applies to using a hose stream on an electrical fire?
30 degree fog pattern
33 feet (minimum) from energized source
100psi (minimum) pumped to nozzle
What is the proper method to clearly identify a LIFE HAZARD ZONE?
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”)
Vehicle should be driven clear of wires how many feet if safe to do so?
35 feet
LADWP can de-energize the lines for a power line rescue in how many minutes?
5 to 10 minutes
OPERATIONS NEAR TRANSMISSION LINES: Maintain a distance of how many feet from towers?
Minimum of 35 feet
Maintain a clearance of how many feet beyond the outermost wire of electrical transmission lines?
100 feet (minimum)
Never direct hose streams into heavy plumes of smoke within how many feet of high-voltage lines?
100 feet
What is the explosive range for Carbon Monoxide (co)?
12.5 to 74%
Always locate manholes in what directions from the involved vault?
All four directions
The IC SHALL ensure that all occupancies?
Inspected for hazards
Manhole covers often weigh?
300 pounds
Manhole covers can be blown how high and at what distance?
75 feet and 125 feet
What is the main fire hazard within electrical vaults?
Cooling oil has a flash point of 300 degrees
UNDERGROUND VAULT: High-Voltage cables up to how many volts?
230,000 volts (may be located close to floor inside conduit)
