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HOT > Ch. 20 Electrical Fires and Emergencies > Flashcards

Ch. 20 Electrical Fires and Emergencies Flashcards

1
Q

Water had pressure, friction loss and flow rate:

A

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

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2
Q

Resistance occurs due to ___________.

A

The material of the conductor

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3
Q

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

A

Open circuit

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4
Q

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

A short circuit

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5
Q

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

A

Utility companies, Utility ground

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6
Q

Many rubber and plastic compounds are

A

Poor conductors

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7
Q

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

A

Not good insulators

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8
Q

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

A

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

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9
Q

Upon leaving generating stations, electricity travels through transformers that:

A

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

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10
Q

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

A

Substations
Underground transformers
Pole-mounted transformers
Transformers inside buildings

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11
Q

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

A

High-voltage wires on poles ARE NOT insulated.

** also true of buss bars (bus bars) in OUTDOOR SUBSTATIONS***

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12
Q

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

A

4,000-33,000 volts

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13
Q

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

A

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

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14
Q

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

A

Electricity

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15
Q

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

A

An air gap
Insulation
Protection

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16
Q

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 ____________.

A

Inaccurate
Less
-the type of metal
-conductive capability

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17
Q

Two main hazards with electricity:

A

Electrocution

Burns

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18
Q

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

A

High voltage

Rapid death

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19
Q

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

A

Current flow

Very, very small

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20
Q

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

A

Size of contact point

Path electricity takes through the body to ground

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21
Q

Electrocution is affected by several variables: (5)

A
  • amount of current
  • size on contact point
  • path to enter/exit the body
  • duration of current flow
  • condition of skin (wet, dry, broken)
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22
Q

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

A

An arc

The result of it

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23
Q

________ is one very common occurrence of such static arcing

A

Lightning

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24
Q

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

A

Voltage gradient

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25
Q

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

A

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

26
Q

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

A

High and low-power carriers

Series and parallel grid systems

27
Q

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)

A

Watch general supervisor

28
Q

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

A

100 people

29
Q

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

A
  • exposes cross-members

- could result in wire breakage

30
Q 
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:
A
  • at least 25 ft from energized equipment

- 40 ft if using SOLID streams or foam nozzles on OTHER THAN SPRAY PATTERN

31
Q

In many urban areas, the most frequent response to electrical emergencies is to:

A

Manhole fires

32
Q

Explosive range of CO

A

12-75%

33
Q

Manhole fire: Checking adjacent bldgs for extension of fire through conduits, what indicates possible fire extension?

A

Heat in the fuse service panel

34
Q

Current flowing through these unintentional conductors (metal objects with no house ground) can be as large as what the building service carries:

A

Hundreds of AMPS

35
Q

Exposed wires at the base of a lamp post contain upward of:

A

277 volts

notify utility last after taping wires and taping off area

36
Q

DANGER AREA for downed wires is defined as area in ALL directions that is at least:

A

As large as the length of the wire in question

37
Q

First tactical consideration is to define the perimeter of the operation by establishing a safety zone that is:

A

One full span greater than the affected span.

38
Q

Although ______, ______, and ______ are all useful tools for lifesaving purposes, you SHOULDN’T rely on them.

A
  • Lineman’s gloves
  • Sleeves
  • Mats
39
Q

Visual hints-overheated ballasts intact bulbs

A 
Bulbs glowing faintly
Look at fixtures for defects
-dark colored oil on outside of fixture/light diffuser
Dark smudge around vents
Last resort, feel each fixture
-defective unit will be hot
40
Q

Life-threatening condition - lines on a car and no hot stick
cannot be used during rainy/damp weather

A 
Dry rope
1st throw under
2nd over 
Far side retrieves and walks backward
*presence of spilled gasoline may remove this option*
41
Q

Although it is true that the level of _______ does the damage, current passing through a body requires adequate _______ to cause the amps to flow.

A

Amperage

Voltage

42
Q

The presence of _______ is usually, if not always, accompanied by _______.

A

High voltage
High amperage
high voltage doesn’t do the damage, but what accompanies it does

43
Q

Many utilities refer to anything ________ as low voltage.

A

LESS than 600V

44
Q

When electricity has performed its function at the appliance or light bulb, it returns to its source via __________.

A

A return wire

45
Q

The larger the ______, the higher the _____ is a valid indicator.

A

Insulators

Voltage

46
Q

In high voltage conductors, the current can jump _______, depending on _____, _____ and _________.

A

3 ft or more
Moisture content of the air
Electrical potential
Type of conductor

47
Q

Fire departments are most often concerned with areas of the distribution system where changes in ______ are made, such as _____, _____ or in __________ that are found in manholes or overhead structures like utility poles.

A

Voltages

Substations
Transformers
Junctions of cables

48
Q

Electricity-related fires and emergencies-
Safety is paramount. The tactical position is ________ until ________. The need for ______ is rare and only justified if human life is at stake. Our concern is the protection of ______.

A

Generally a Defensive one
Power is shut down

Offensive tactic

Exposures

49
Q

In a generating station, water heated, turning it to steam at over _______. Accompanied by _________ and a ___________.

A

400 psi

Tremendous shrieking
Cloud of condensing water vapor

50
Q

Generators are cooled with _________, a lighter than air gas __________ that it often ignites immediately in the event of a leak. When it burns, it is with a __________.

A

Hydrogen
Highly flammable

Very pale flame, nearly invisible

51
Q

Actions to be taken-

Inside generating station:

A

Do not enter until rep arrives unless human life in jeopardy
Stretch a line to standpipe/sprinkler but do not enter
No metal tools
No ladders, even wood, supported by metal superstructure
Fog tips

52
Q

Transformer fire:

A

Class B-oil fire
Up to 20,000 gallons
All oil presumed to have PCBs (breaks down to dioxin/dibenzofurans)
Do not begin overhaul until advised by utility of nature of oil

53
Q

Manhole fires

Rumbling noise we hear at manhole fires is ________.

A

Ongoing electrical arc

Variety of high/low voltage but relatively few transformers
Large amounts of CO/HCL when gases contact mucous membranes
Less lethal dose of CO with HCL
Transformers found in vaults with square/rectangular covers

54
Q

Signs of open ground:

What to do:

A

Dimming of lights/presence of sparks at contact point of metal objects/overheating of building’s electrical wires

Open individual breakers/circuits, reducing load
Handlines
Notify utility

55
Q

Downed line can be ____, ____ or ______.

A

Dancing, arcing or just lying still

56
Q

Trained FF may use a properly tested ______ to remove wires from direct contact with a ______ or ______. Secure the hot stick around the wire by placing the clamp ______ the wire and twisting the body of the stick __________.

A

Hotstick
Victim or vehicle

Under
Clockwise

57
Q

If necessary to cut the line, secure the wire with a _____ or a __________ objects such as __________. Tingling sensation is an indication of ________ and imperative _______ before any further action.

A

Hot stick
Heavy, nonconductive
Long, dry, wooden boards

Voltage gradient
Power be shut down

58
Q

Wire over car with people in it (3 scenarios)

A

Driver can move vehicle, drive it out from under wire
Vehicle can’t move, no life-threat, do not remove occupants
Fire threatens occupants, jump clear of vehicle
stretch 1 3/4 in. with fog

59
Q

Ballasts
Older types, often ______. Should wear _____. Thermal imaging cameras or other types of ____________ devices can be used. Without a _________, must physically inspect each fixture.

A

PCB’s, SCBA.
Heat scanners

Heat scanner

60
Q

Electrical fire are common occurrence. To locate source, consider __________________. It often pays to ___________.

A

Where SMELL was first detected

Leave power on until source is located

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