Ch. 20 Electrical Fires and Emergencies Flashcards Preview

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Flashcards in Ch. 20 Electrical Fires and Emergencies Deck (60)
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1

Water had pressure, friction loss and flow rate:

Pressure = volts (electromotive force OR electrical potential difference)
Friction loss = ohms (resistance)
Flow rate = amperes (amps)

2

Resistance occurs due to ___________.

The material of the conductor

3

_______ does not permit electricity to flow because there is a break in the circuit wire.

Open circuit

4

When an electrical circuit's normal path has been INTERRUPTED, it becomes _________ , permitting current to flow through a path it was not intended to travel.

A short circuit

5

Wiring installed by _________ that permits electricity to flow back into THEIR system and then into the earth is called:

Utility companies, Utility ground

6

Many rubber and plastic compounds are

Poor conductors

7

Firefighting boots, either rubber or leather, are ___________ however, because of many other compounds they contain.

Not good insulators

8

Most electricity is produced by ______, in facilities that use fuel as sources of energy (____, ______, _____, or ______). Electricity is generally produced at ___________.

Generators
Coal, oil, gas or nuclear
13,000 volts

9

Upon leaving generating stations, electricity travels through transformers that:

Increase it's voltage to 138,000-345,000 volts

10

(Voltage) Stepping down done in several stages, in different locations: (4)

Substations
Underground transformers
Pole-mounted transformers
Transformers inside buildings

11

Most IMPORTANT thing for firefighters to be aware of in regard to the TRANSMISSION system is:

High-voltage wires on poles ARE NOT insulated.
** also true of buss bars (bus bars) in OUTDOOR SUBSTATIONS***

12

Once at the point of distribution, other transformers reduce the voltage to:

4,000-33,000 volts

13

Electricity is then fed through a grid of cables/transformers that take it right to the customers door. On the way, the voltage is:

Further stepped down to 120 or 240 volts normally used in the home or the office

14

_____ is moving force that travels through solid, liquid, and gaseous materials in the form of electron transfer from one molecule to another.

Electricity

15

Economy of high-voltage transmission uses ________ between lines instead of _______. Distance is _______.

An air gap
Insulation
Protection

16

It would be _______ to state that the larger the line, the higher the voltage.
In some cases, a larger transmission line carries _____ voltage than a small one
- depending on ______ and its ____________.

Inaccurate
Less
-the type of metal
-conductive capability

17

Two main hazards with electricity:

Electrocution
Burns

18

_______ flows through the body, either due to high-voltage or low resistance, cause ______.

High voltage
Rapid death

19

Amount of ________ through the body to produce injury or death is __________.

Current flow
Very, very small

20

_____ and _______ are important factors that help determine whether a person survives a contact with electricity.

Size of contact point
Path electricity takes through the body to ground

21

Electrocution is affected by several variables: (5)

-amount of current
-size on contact point
-path to enter/exit the body
-duration of current flow
-condition of skin (wet, dry, broken)

22

It is usually the presence of _____ or ________ that triggers the response of firefighters.

An arc
The result of it

23

________ is one very common occurrence of such static arcing

Lightning

24

______ is the result of current being dissipated to ground as it travels from a source, such as downed high voltage wire.

Voltage gradient

25

Carries vary in voltage potential, depending on the stage of transmission:

Transmission line = exceed 8,000 volts
Distribution line = potentials of 601-8,000 volts
Low-voltage potentials = up to and include 600 volts

26

System for distribution of electricity includes a combination of transformers with ___________, arranged in __________

High and low-power carriers
Series and parallel grid systems

27

In most power generation plants, the ______________ has access to emergency operations cabinet (station diagrams, system/relay drawings, log books, current list of all equipment containing PCB's)

Watch general supervisor

28

Charts that show emergency posts and jobs for all staff can in large plants number more that ______.

100 people

29

Transformer is atop a pole, make no attempt to extinguish fire unless:

-exposes cross-members
-could result in wire breakage

30

Transformer atop a pole:
If necessary to extinguish, use a fog or foam stream, or dry chem extinguisher. It is essentially a confined class B-type fire, use reach of hose stream, outside safety zone and:

-at least 25 ft from energized equipment
-40 ft if using SOLID streams or foam nozzles on OTHER THAN SPRAY PATTERN