TB-8 Electrical Hazards Flashcards
Amps can be described as:
Current or electron flow.
Current flows from points of high voltage to low voltage on the surface of a conductor.
Volts:
Push or pressure behind current flow through a circuit. (psi)
Voltage is the difference in electrical potential between two points in a circuit.
Ohms:
Resistance
Ohms Law:
Watts=amps x volts
Amps=watts/volts
Volts=watts/amps
One ohm is the resistance value through which one volt will maintain a current of one ampere.
Watts:
Watts=amps x volts
Power is the amount of current times the voltage level at a given pint measured in wattage or watts.
What is considered extremely high voltage?
Voltages in excess of 60,000 volts. Usually transmission voltage.
High voltage is:
Voltage from 600 volts up to 59,999 volts.
primaries
Low voltage:
Usually below 600 volts.
secondaries
Getting electricity to the consumer can be broked down into 3 systems, ___________,_____________, and _____________.
Generation, Transmission, and Distribution System.
Generation facilities produce between __________ and ____________ volts.
4,000 and 20,000 volts
Voltages on transmission lines range from _______ to _________.
69kv to 1000kv.
All voltages above 69kv are referred to as transmission voltages.
Strings of insulators on transmission towers can range from ____ to ____ ft long.
3 to 20 ft.
What are the dangers of a high voltage capacitor?
They can retain a deadly electrical charge even weeks after the power has been removed from the circuit. Older versions contain dangerous chemicals.
Overhead transformers are installed on the 4.8kv circuits to step down the voltage down to _____/______ volts.
120/240
True or false? The voltage of a conductor can be determined by the conductor’s size.
FALSE
The three most effective method of identifying different voltages are:
- High voltage signs on the cross arms.
- The size and shape of insulators, the insulators at the tops of poles will appear smaller than they really are.
- The distance between the conductors. The higher the voltage, the greater the distance between conductors.
The four main types of electrical injuries are:
Electrocution (death)
Electrical shock
Burns
Falls
For example, ____ of an amp of electricity going through the body for just two seconds is enough to cause death.
1/10
For every minute that defibrillation is delayed, the patient sustains a ____% reduction in their chances of survival.
10
The most common shock related injury, non fatal injury is a ______.
burn
Ultimately, the danger from electrical shock depends on the:
AMOUNT, DURATION, and PATH of the shocking current through the body.
When a burn injury does not meet base station criteria, the member shall be transported directly to ________, or ___________.
Grossman Burn Center at West Hills Hospital or Torrance Memorial Hospital Burn Center.
Overhead communication cable normally found on the lowest level of a power pole can be energized up to ____ volts. Can cause a fall off the aerial.
50
When spotting apparatus, have personnel maintain at least ___________ from the affected wire or pole.
One span (distance between two poles). Do not count damaged pole.
Street lights can be fed from conductors carrying _______ volts or more.
120-6150 volts
The factors that increase the conductivity of water are ________ and ________ in water.
dissolved minerals and impurities
Use the 30/33/100 Rule for using hose streams around high voltage:
- 30 degree fog pattern
- Stay 33 feet away from the energized source.
- 100 psi at the nozzle.
For victims trapped in a car touching wires, the vehicle should be driven clear of the wires by at least _____ ft.
35
A charge of static electricity capable of jumping ____ to ____ inches may build up in a person’s body when climbing a tower.
2 to 3
During brush fires, maintain a distance of ____ feet from transmission towers.
35 feet.
During brush fires, maintain a clearance of ____ feet beyond the outermost wire of electrical transmission lines.
100 ft.
During brush fires, never direct hose streams into heavy plumes of smoke within ____ feet of high voltage wires.
100
The explosive range for carbon monoxide is _______ percent.
12.5 to 74
Manhole covers often weigh _____ and have been blown ____ feet into the air and a distance of _____ feet.
300 lbs, 75 feet into the air, and a distance of 125 feet.
The apparatus is not insulated from the ground by its rubber tires and it may be energized by live wires in the following ways:
- By touching an object that is in contact with a live conductor
- By direct contact with a live conductor
- By an extended aerial ladder touching a live conductor
A square manhole indicates a ________________.
Transformer vault
The main hazard within electrical vaults lies in the ________ used in the transformers, which has a flash point below _________.
Cooling oil, 300 F
High voltage cables, up to _________volts, may be located close to the floor inside a conduit containing ______ psi oil pressure.
230,000 volts, 200 psi oil pressure
Electrocutions have resulted in more than ____ deaths in the fire service in the last 20 years.
25
