TB #8 Electrical Hazards at Fires Flashcards
Quantity of electricity is expressed in __
Amperes (amps)
Electrical pressure is measured in __
Volts
Electrical resistance is measured in __
Ohms
Extremely high voltage __
Voltages in excess of 60,000 volts
High voltage __
Voltage from 600 volts up to 59,999 volts
Low voltage __
Usually below 600 volts
Conductor =
Hose
Current =
Water
Voltage =
Pressure
Amperes =
Gallons per minute
Ohms =
Friction loss
Generation facilities generate electricity between __
4,000 and 20,000 volts
Voltages on transmission lines range from __
69kv to over 1,000 kv
Most of the transmission lines coming into Los Angeles are __
230kv
All voltages above __ are referred to as transmission voltages
69kv
The LADWP also has a number of transmission lines with voltages of __ or __
138kv, 230kv
The voltage is stepped down __ in the distribution system before it is delivered to most consumers
Three times
The LADWP has __ receiving stations which receive the electricity at transmission voltages (__ to __) and step the voltage down to __
21, 138kv, 500kv, 34.5kv
There are over __ distribution stations where the electricity is received at __ and stepped down to __
150, 34.5kv, 4.8kv
High voltage capacitors have been known to retain a deadly electrical charge even __ after power has been removed from the circuit
Weeks
Many commercial and industrial installations have service conductors of __
34,500 volts
The most effective methods of identifying different voltages are__
High voltage signs on the cross arms, the size and shape of insulators, the distance between conductors
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 __
10 milliamps (mA)
Currents above __ can paralyze or “freeze” muscles
10 mA
Usually it takes about __ of current to cause respiratory paralysis
30 mA
Currents greater than __ may cause ventricular fibrillation
75 mA
Dry skin may have a resistance of __or more
100,000 ohms
Wet skin may have a resistance of only __
1,000 ohms
Ultimately, the danger from electrical shock depends on the __
Amount of the shocking current through the body, duration of the shocking current through the body, path of the shocking current through the body
Voltage gradient is__
A decreasing current created when a energized wire is in contact with the earth
Touch potential occurs __
By contacting a live or energized source
Step potential 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
Aerial ladders must be kept at least __ away from all power lines and devices
Ten feet
Responding personnel need to maintain at least __ from the affected wire or pole
One span (the distance between two poles)
Streetlights can be fed from conductors carrying __or more
120-6150 volts
LADWP maintains approximately __ distribution stations in the city
150
Utilize the __ for using hose streams around high voltage
30/33/100 rule
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 __ of barrier tape that state “Do Not Enter” or “Do Not Cross”
Three (3) horizontal strands
Vehicles should be driven clear of wires by at least __
35 feet
Minimum safe distance from transmission towers __
35 feet
Maintain clearance a minimum of __ beyond the outermost wire of electrical transmission lines
100 feet
Remain at least __ from transmission lines and __ from transmission towers
100 feet, 35 feet
Manhole covers often weigh __ and have been blown __ into the air and a distance of __
300 pounds, 75 feet, 125 feet
Water and Power line patrolman’s apparatus operates __ a day, is radio equipped, and can usually reach any area of the City within __
24 hours, ten minutes
LADWP tests gloves to __ every __
10,000 volts, 60 days
Indicates a transformer vault
Square manhole
Flash point of cooling oil used in transformers of underground vaults
Below 300 degrees Fahrenheit
High voltage cables in underground vaults can be up to __
230,000 volts
Conduit in underground vaults contains __ oil pressure
200 psi