TB 8 Electrical Hazards Flashcards
According to NIOSH, electrical accidents in the US account for #_____ deaths per year
700
OSHA statistics indicate that electrocution accounts for ____%of worker deaths annually
12%
NIOSH statistics also document that over the last __years, electrocutions to first responders have resulted in more than ___deaths in the fire service.
20
25
Los Angeles Fire Department (LAFD) resources respond to over ______electrocutions, wires down, and other electrical emergencies annually.
3000
_____ is one of the basic charges of energy
Electricity
_______ _________ can be stationary, as in static electricity
Electrical Charges
An _____ _______is a movement of charge
Electric Current
True/False.
When two objects with the “same” charges touch and redistribute their charges, an electric current flows from one object to the other until the charge is distributed according to the capacitance of the objects.
False. Different Charges
What is Current flow, or electron flow; it is what flows on a wire or conductor like water flowing down a river.
AMPS
The measure of Current that flows from points of HIGH voltage to points of LOW voltage on the surface of a conductor is ….
AMPS
Quantity of electricity is expressed in ______,
e.g. water is measured in gallon per minute(gpm).
AMPS
What is the difference in electrical potential between two points in a circuit
VOLTS
What is the push or “pressure” behind current flow through a circuit.
VOLTS
Electrical pressure is measured in ______
E.g. in water hydraulics would be (psi).
VOLTS
The measure of 1000 volts.
KILOVOLTS
Measurement commonly used by LADWP
KILOVOLTS
Electrical “resistance” is measured in ________
E.g. The resistance to a flow of water through a hose would be termed friction loss
OHMS
OHMS. ________ determines how much current will flow through a component.
Resistance
E.g. very high resistance = small amount of current flow
OHMS. _______are used to control voltage and current levels.
Resistors
____________defines the relationships between power (watts), voltage (volts), current (Amps), and resistance (ohms).
OHM’s LAW
_______=amps(current) x volts
WATTS(power)
_____= watts(power)
———————
Volts
Amps(current)
________= Watts(power)
———————-
Amps(current)
Volts
voltages in excess of 60,000 volts. Usually transmission voltage.
Extremely High Voltage
voltage from 600 volts up to 59,999 volts.
Usually found in customer distribution system.
High Voltage
Referred to as “Primary circuit voltage” or “Primaries”
High Voltage
In the LADWP system the primary distribution lines are usually______
4.8 Kv
_______ is below 600 volts
Low Voltage
_____ is called “secondary circuit voltage” or “secondary”
Low Voltage
Electricity Fire Hydraulics
Hose = Water= Pressure= Gpm’s= Friction Loss=
Conductor Current Voltage Amps Ohms
What are the 3 ways Getting electricity to the consumer can be broken down ?
Generation , Transmission, Distribution Systems
_________is where the electrical energy transformation process originates and where a complete circuit starts.
Generation Power Plants
_________use mechanical energy, such as water pouring through a dam or the motion of a turbine driven by steam, to produce electricity.
Generators ( generation system)
___________create electricity by using other forms of energy such as “fossil fuel steam plants, hydroelectric dams, nuclear power plants “
Generators
Generation facilities generate electricity between_____ &______ volts.
4000 and 20,000 volts.
True/False.
Generators produce enough volts to deliver power long distances to connect different parts of the city together.
False.
In order to raise the voltage for generation stations they rely on _________?
Transformers
_________ take the electricity from the generation plant and begin the flow of current over the longdistances needed to carry it over transmission lines.
Switchyards
_______utilize their own magnetic fields to lower required amps while proportionately raising the pressure (voltage), sometimes to over one million volts.
Switching Facility Transformers
_______ are called “step up” transformers because they step voltage up
Switching Facility Transformers
What are the 2 main components of the transmission system.
Grids & Transmission Lines
What are the layouts of the electrical distribution system which is a system of wires, substations, and switchyards throughout the transmission system.
Grids
__________are used to carry the electricity from generation stations in a system of wires that carry electricity to the grid.
Transmission Lines
__________are used to carry high voltage electricity the long distances from generating plants to distribution stations.
Transmission Lines
What are the Most common transmission lines in Los Angeles
Overhead Transmission Lines
_______are also called high-voltage or high-tension wires.
Overhead transmission lines
Voltages on transmission lines range from___ to____
69 Kv to 100 Kv
Most of the transmission lines coming into Los Angeles are _____
230 Kv or higher
All voltages above ____are referred to as transmission voltages.
69 Kv
Strings of insulators on transmission towers can range from ____ to _____long depending on the voltage they are trying to hold back from contacting the towers that support them.
3-20 ft
LADWP has transmission lines with voltages of _____ to ______?
138 Kv— 230Kv
The component of the electric system that delivers electrical energy to the consumer or residence consists…..
Distribution stations & lines.
Distribution System
The ______________ is a group of electric stations, high- and low-voltage power lines and poles, surface and underground transformers located through out the city.
Distribution System
How many times is voltage “stepped down” in the distribution system before it is delivered to most consumers?
3
What are Substations that utilize transformers to change high-voltage electricity into lower voltage? ( Begins at the receiving station)
LADWP DISTRIBUTION STATIONS
What carry electricity from the distribution system to homes, offices and factories which require low-voltage electricity.
Distribution Lines
________ _______ ________consists of wires mounted on steel or wood poles(Most common type in City of Los Angeles).
Overhead Distribution System
_______ are lines inserted in conduits or ducts and buried in ground
Underground Distribution
How many receiving stations does LADWP have?
21
Receiving stations receive electricity @ ______ to ____ Kv
138Kv to 500 Kv
Receiving Stations step the voltage down to___ Kv, which is referred to as a sub-______
34.5 Kv
Sub-Transmission
There are over _____distribution stations where the electricity is received at 34.5kv and stepped down to 4.8 kv.
150
Distribution stations where the electricity is received at 34.5kv and stepped down to 4.8 kv. are known as _____ ______ ______
Primary Circuit Voltage
Each primary line has an average of ____consumers
750
LADWP has over _______ primary circuits
1500
What appliances are used to increase or decrease the voltage of the electrical current.
Distribution Transformers
What are designed to reduce the voltage in the system to a voltage usable by the consumer.
Transformers
_______ allows electricity to be efficiently transmitted over long distances.
Transformers
_________is a type of electronic component which passively acts as a form of conductor.
High Voltage Capacitor
Overhead Transformers: _________transformers are the most common distribution transformer
Pole mounted
Overhead pole mounted transformers are installed on the____ Kv circuits to step the voltage down to ______ volts for most residential consumers.
4.8 Kv
120/240
These transformers are used for subsurface electrical and are mounted above ground on concrete bases
Pad mounted transformers
What are large boxes connected to 4.8kv circuits and are located in parking lots of small and medium size businesses or in the front yard of some residences.
Pad mounted transformers
True/False. Voltages for subsurface electrical distribution utilities are the same as in overhead systems.
True
True/False. Underground electrical wires have the same insulation and the cable is same length as above ground transformers.
False. Better insulated & Larger cables
Pad mounted transformers are connected to ____ Kv circuits
4.8Kv
What are the configurations of Underground Electrical Distribution lines?
underground, subsurface, and direct buried.
Underground lines can be found in conduits or ducts and are identified by warning signs labeled____
UG
Electrical distribution lines placed directly in the ground are labeled____
DB(direct buried)
What are materials that allow an electric current to flow through them easily?
Conductors
What are two good conductors?
Humans and most metals
What are 3 different things that can be conductors?
Wire
Cable
Rod
What is the most common conductor?
Electrical wire
The voltage of a conductor cannot be determined by the conductor’s________.
Size
What are appliances which will prevent the flow of electricity and provides support to the conductor?
Insulators
What are insulators most commonly made of ?
Glass & Porcelain
What are the wires that connect the customer or home to the secondary transformer and may be high or low voltage.
Service connection
Many commercial and industrial installations have service conductors of______volts.
34,500 volts
The most common type of Service Connection is the ____
Triplex( three wire method )
The most effective methods of identifying different voltages are:
- High voltage signs on the cross arms.
- The size and shape of insulators; remember, the insulators at the top of poles will appear smaller than they really are.
- The distance between conductors; the higher the voltage, the greater the distance between conductors.
Usually the conductors @______ of the pole carry the highest voltage
Top
_______occurs when current passes through the body.
Electrical Shock
The degree of electrical shock and resulting injuries depends on the_____and the______
amount of current
length of time the current passes through the body.
In any instance by which electricity can find a path to earth or ground, be it a failed transformer or switch, downed wire or contact with a person, a _____ _______will occur.
Short Circuit
What are the 4 Main types of Electrical Shock ?
- Electrocution (death due to electrical shock)
- electrical shock
- Burns
- Falls
_______ of an amp of electricity going through the body for just _____seconds is enough to cause death.
1/10th
2
Currents above______can paralyze or “freeze” muscles
10 mA(milliamps)
Usually, it takes about ____of current to cause respiratory paralysis.
30mA(milliamps)
Currents greater than ____may cause ventricular fibrillation (very rapid, ineffective heartbeat).
75mA(milliamps)
For every minute that defibrillation is delayed, the patient sustains a ___%reduction in their chances for survival.
10%
Heart paralysis occurs at __amps, which means the heart does not pump at all.
4 amps
Tissue is burned with currents greater than __amps.
5 amps
At ____volts, the current through the body may be as great as 4 amps, causing damage to internal organs such as the heart.
600 volts
Differences in ____ & _____ content affect the severity of shock
Muscle & Fat content
Effects of shock depend on what ?
Amount of current
Duration
Path through the Body
Small power drills uses ____ times as much Current to cause death
30
Dry skin may have a resistance of ______ohms or more.
100,000
Wet skin may have a resistance of only _______ohms.
1000
The most common shock-related, nonfatal injury is a _____
Burn
______are one of the most serious injuries you can receive.
Electrical Burns
when a burn injury does not meet base contact criteria, the member shall be transported directly to …
LA County USC Hospital
Grossman Burn Center at West Hills Hospital
Torrance Memorial Hospital Burn Center
Who shall you notify to respond to any burn injury?
Arson
Firefighters responding to emergencies involving electrical equipment must …
Wear Full PPE
What are the 2 main methods for de-energizing a building ?
- Main switch or Breaker switches at electrical panel
2. Cutting wires utilizing LAFD equipment
Do not cut the ______wire in triplex unless there is a danger of it falling, or if there is a possibility that it has become energized.
Bare wire
What Is a decreasing current created when a energized wire is in contact with the earth. The ground soil becomes a conductor and will allow current to travel a distance from an energized source, such as a fallen wire. The current spreads out from point of the energized source like ripples in a pond. A person stepping into this ground gradient will receive an electrical shock.
Voltage Gradient
This Occurs by contacting a live or energized source.
Touch Potential
This commonly occurs when a vehicle, fence or other conductor is in contact with a live conductor such as a “downed wire”
Touch Potential
This 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.
Step Potential
True/False. The Fire Apparatus is insulated from the ground by its rubber tires
False
There are several standards that cover electrical hazards that are established by who ?
OSHA
TITLE 19 Code of Federal Regulations
NFPA Standard 70E
For voltages of 600 or more, Cal/OSHA and NFPA standards require that aerial ladders be operated at a minimum clearance of _____of power lines and electrical devices.
10 ft
LAFD Policy state that Aerial Ladders MUST be kept at least 10 ft from _____ power lines
ALL*
Department members shall not work in violation of the 10-foot rule unless participating in an___
Actual Rescue Attempt
Who SHALL remain at the pedestal to provide for personnel safety and ensure safe operation of the aerial if required during an attempt rescue on aerial within 10 ft of power lines
Apparatus Operator
Manufacture policy states that Aerial ladder placement must allow for ladder _____ , _____, _______around electrical wires.
Sway
Rock
Sag
Even overhead communication cable normally found on the lowest level of a power pole can be energized with up to_____
50 volts
Any overhead power line SHALL be considered energized until _______verify that the line is not energized, and the line is visibly grounded at the work site.
LADWP Personnel
If apparatus does become energized:
- Utilize emergency traffic procedures to notify all personnel of the hazard.
- Request MFC to contact LADWP for immediate dispatch.
- Do not attempt under any circumstances to “raise or move high-voltage lines”.
- If apparatus touches a high-voltage line, the operator should back the equipment away or lower the aerial to break contact with the power line.
Although LAFD ladders are wood construction, they are still ______
Conductive
The most common electrical problem firefighters respond to is_____ ______
downed wires.
RESPONDING TO ELECTRICAL EMERGENCIES: Spot apparatus and have responding personnel maintain________ from the affected wire or pole.
at least one span (the distance between two poles) .
If the pole is damaged don’t count the damaged pole.
CONSIDER ALL POWER LINES TO BE ENERGIZED UNTIL THEIR ACTUAL CONDITION IS DETERMINED BY _____
LADWP.
Streetlights can be fed from conductors carrying between ____ &_____volts or more.
120-6150 volts
LADWP considers street lights to be energized with ____ _____at all times.
High voltage
Utilize the ________Rule for using hose streams around high voltage:
30/33/100
- The fog spray should be set at a 30-degree fog pattern
- Firefighters applying water should maintain a distance of at least 33 feet from the energized source.
- Ensure a minimum of 100 psi. is pumped to the nozzle. A strong stream will reduce conductivity.
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 _____
3) horizontal strands of barrier tape that state “Do Not Enter” or “Do Not Cross”
horizontal strands of any Fireline tape or flagging tape shall be between __and __inches
1&3
vehicle should be driven clear of the wires by at least…
35 feet
What 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 hops from the car.
Jump from the vehicle without touching it and shuffling the feet together.
Operations Near Transmission Lines
Maintain a safe distance from transmission towers: a minimum of ____should be adhered to.
35 feet
Operations Near Transmission Lines
Maintain clearance a minimum of ___feet beyond the outermost wire of electrical transmission lines.
100
Operations Near Transmission Lines
Never direct hose streams into heavy plumes of smoke within ___feet of high-voltage wires
100
ELECTRICAL HAZARDS AT WILDLAND FIRES
Assign a lookout to serve as a _____to ensure that the location of the downed line is communicated to all fireground personnel.
Spotter
ELECTRICAL HAZARDS AT WILDLAND FIRES: Conductivity of Smoke
With heavy smoke present, firefighters should be especially cognizant of remaining at least ___feet from transmission lines and ____feet from transmission towers.
100
35
The explosive range for carbon monoxide (co) is____-____%
12.5-74%
Manhole covers often weigh?
300 poumds
Manhole covers have been blown ___feet into the air and a distance of ____feet.
75 ft
125 ft
UNDER GROUND VAULT
If a manhole cover is in place and smoke is issuing from the holes in the cover, do not attempt to…
remove the cover.
UNDER GROUND VAULT
Any entry made to rescue a downed worker or patient must be considered a ______ _____ _______ and appropriate ______ ______ _____resources shall be requested.
confined space rescue emergency
Urban Search and Rescue
What 2 pieces of equipment are used to cut down power lines?
- Mechanical Axe
2. Gauntlet Gloves
The LADWP tests gloves to____volts every _____days.
10,000 volts
60 days
