Ch. 20: Electrical Fires & Emergencies Flashcards
Ch. 20: Norman – Electrical Fires & Emergencies
(NC #1)
___ is the power that moves industry and provides us with convenience in our daily life:
Electricity
Ch. 20: Norman – Electrical Fires & Emergencies
(NC #2)
Electricity is actually a moving force that travels through (3) materials, in the form of electron transfer from one molecule to another:
- Solid
- Liquid
- Gaseous
Ch. 20: Norman – Electrical Fires & Emergencies
(NC #3)
To simplify the ID of the various phases of the force that are at work – labels are attached to them. Bear in mind, that although numerous terms are used, its actually:
The same force being described in different forms.
Ch. 20: Norman – Electrical Fires & Emergencies
(NC #4)
Electricity has pressure – known as:
- Electromotive force -or-
* Electrical potential difference.
Ch. 20: Norman – Electrical Fires & Emergencies
(NC #5)
Electricity has pressure, known as electromotive force or electrical potential difference, and is measured in:
Volts
Ch. 20: Norman – Electrical Fires & Emergencies
(NC #6)
(Norman uses comparison of electricity to water): Electricity’s friction loss - which is the measure of the resistance that it meets is measured in:
Ohms
Ch. 20: Norman – Electrical Fires & Emergencies
(NC #7)
- The flow rate in water is referred to in terms of:
- In electricity, it is called:
- Gallons per minute.
* Amperes (amps for short)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #8)
Amperage (amps) can be thought of as being:
The amount of electricity that a wire is carrying.
Similar to how many gallons per minute a hose is flowing.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #9)
Amperage is determined by the:
- The amount of voltage the conductor is delivering -and-
* The resistance that the wire or object in the path of the current is offering.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #10)
Amperage → T or F – You can tell how much current a wire carries by looking at it:
False – Cannot tell
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #11)
- Amperage ¬¬→ Assume all wires carry sufficient current to:
- It takes far less than ___ amps passing through your body to kill you:
- Kill.
* 1 amp.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #12)
Voltage → Can be described as the pressure that:
Forces electrical current through the lines that carry it.
Similar to the way we use pressure to move water.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #13)
Voltage → As with amperage, you cannot tell the amount of voltage a wire is carrying by looking at it. Voltage can vary in the same size wires. High voltages increase the tendency of electricity to:
Arc to ground across an open space
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #14)
Voltage → Is the following statement true – ‘it is the amps that kill, not the voltage.’
Not entirely true and can be misleading.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #15)
Voltage → (CFPC) – It is true that level of amperage does the damage, current passing through a body requires ___ to cause the amps to flow:
Adequate amperage
this is why high-voltage levels are dangerous
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #16)
Voltage → The presence of high-voltage is usually accompanied by the presence of:
High-amperage
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #17)
Voltage → ‘it’s the amps that kill, not the voltage’ – The high voltage does not do the damage, but what accompanies it does. The danger posted is relative & depends on many variables that can be present – such as:
Potentially lethal – regardless of the labels associated with them.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #18)
Voltage → It is wise & prudent to treat all electrical emergencies as potentially ___.
Potentially lethal – regardless of the labels associated with them.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #19)
Voltage → Most of the situations that a FF will encounter involve various elements of the ___ system, and the power company’s labels can be misleading to the layperson.
Power distribution
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #20)
Voltage → Many utilities refer to anything less than ___ as “low” voltage:
600 volts
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #21)
Resistance → Can be thought of in terms of the ___ offered to the electricity:
Resistance to flow
(Norman’s analogy → a cracked nozzle provides resistance to water flow – consequently, there is little volume (amperage) delivered. If nozzle fully open or removed entirely – less resistance to flow & volume delivered (amps) increases.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #22)
Resistance occurs due to the:
Material of the conductor
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #23)
Resistance → Occurs due to the material of the conductor. Materials that are good conductors offer little resistance to flow, while poor conductors – offer high resistance. Many ___ are poor conductors:
Rubber & plastic compounds
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #24)
Resistance → Good conductors of electricity include:
Copper – and other metals
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #25)
FF boots (either leather or rubber) are not good ___, bc many of the compounds they contain:
Insulators
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #26)
Dry skin isn’t a good conductor – but the amount of pressure behind a high-voltage line can force electricity through even a poor conductor. When skin is ___, it becomes a good conductor:
- Does not permit electricity to flow –
* Bc there is a break in the circuit wire, or an open switch.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #27)
Resistance → Open circuit – An open electrical circuit (does or does not) permit electricity to flow because:
- Does not permit electricity to flow –
* Bc there is a break in the circuit wire, or an open switch.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #28)
Resistance → Short circuit – When a electrical ___, it becomes a short circuit:
When an electrical circuit’s normal path has been interrupted – it become a s/c.
Permitting current to flow through a path it was not intended to travel.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #29)
Resistance → Utility ground – This is:
- The wiring installed by the utility companies –
* That permits electricity to flow back in to the system and then into the earth (or ‘ground’).
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Terminology (NC #30)
Resistance → House ground – Wiring called house ground is:
- Installed by an electrician when building a house.
- The house ground permits electricity to flow back into the earth (or ground) in the event that the utility ground is broken or ‘open.’
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #31)
Most electricity is produced by ___, in facilities that use fuel as the source of energy. Sources of energy include:
• Generators
- Coal
- Oil
- Gas
- Nuclear
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #32)
Most electricity is produced by generators, in facilities that use fuel as a source of energy (coal, oil, gas, nuclear). This electricity is generally produced at __ volts:
13,000
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #33)
Upon leaving the generating station, electricity travels through transformers, that increase its voltage to:
138,000 – 345,000 volts
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #34)
- 20-1: The ___ station is responsible for the quality of live we enjoy today:
- This power moves out of the plant over large-capacity uninsulated conductors carrying upwards of ___ volts:
- Power generating station
* 300,000 volts.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #35)
Upon leaving generating station, electricity travels through transformers (that increase its voltage to?). This step is taken in preparation for:
- Moving the current over great distances –
- To the areas where it will be distributed.
- BC – high-voltage current travels more efficiently than low-voltage current.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #36)
(CFPC) – Once at that point of the distribution, other transformers reduce the voltage to:
- 4,000 – 33,00 volts.
- Produced at – 13,000 volts.
- Transformers – 138k – 345k volts.
- Reduced – 4k – 33k.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #37)
20-2: The neighborhood substation takes power from very-high voltage transmission lines & reduces it to ___ or ___ voltages:
Midrange or distribution
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #38)
20-2 (cont): The neighborhood substation takes power from very-high voltage transmission lines & reduces it to midrange or distribution voltages, commonly ___ volts:
27,000 volts
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #39)
20-2 (cont): Neighborhood substation – The silver ‘pipes’ about ‘14’ off of the ground, are actually:
- Buss bars –
- High voltage conductors.
- (Power must be removed from the facility before fire or emergency operations can safely be conducted inside)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #40)
(Cont. From NC #36) – The electricity is then fed through a grid of cables & transformers that take it right to the customer’s door – On the way, the voltage is further stepped down to ___ volts normally used in the home or the office:
120 or 240
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #41)
The most important thing for FFs to be aware of in regard to the transmission system is that:
High voltage wires are not insulated.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #42)
The most important thing for FFs to be aware of in regard to the transmission system is that high voltage wires are not insulated. That is also true of ___ on outdoor stations:
Buss bars (sometimes called bus bars)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #43)
With electricity, the ___ is increased to push more of the power through the carrier:
Pressure (volts)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #44)
When electricity reaches its destination, ___ convert it to match consumers’ needs:
Transformers
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #45)
When electricity has performed its function at the appliance or light bulb, it:
Returns to its source – via a return wire.
not unlike water – which when its been used, finds its way into the sewer system to ultimately return to its source
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #46)
(CFPC) – As with water deliver, the ___ changes to maximize the efficiency of the delivery system, and this conversion is made at, or close to, the use location to match the need:
Mode of transport
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #47)
20-3: Typically the ___ (higher or lower) a wire is on a pole, the lower the voltage.
Lower
dangling high-voltage wires could energize a telephone or cable tv wire w/ deadly current
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #48)
- 20-3 (cont): Utility pole – The top wires may carry more than ___ volts:
- ___ & ___ are indicators of high voltage:
- 13,000 volts.
* Number & size of porcelain insulators.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #49)
Keep in mind – size of the electrical transmission line will vary. A carrier of the same potential (voltage) may be of different sizes, depending on:
The substance from which it is made – such as copper or aluminum alloy.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #50)
(CFPC) – This is unlike water carriers, where the size (diameter) of the conduit is the primary factor in transmission for:
Pressure & FL calculations
(rather than the construction & substance of the hose).
Section: The Power Distribution System (NC #51)
(CFPC) In electricity, the relationship of the diameter of the transmission pressure isn’t a strong consideration. W/ cables, problems of burst lengths & FL are also not strong factors (as w/ water in comparison), so high very ___ can be generated & used to provide more power potential over large distances at greater economy:
High pressures (kilovolts)
Summarize this NC
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #52)
It would be (accurate or inaccurate) to state that the larger the line, the higher to voltage:
In accurate
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #54)
The old notion of ‘the larger the line, the higher its voltage’ is no longer a rule of thumb that can be relied upon, although the size of any ___ that can be seen on a line can give an indication of the relative voltages involved:
Size of any insulators
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #55)
The larger it ___, the higher the voltage is a valid indicator.
Insulator
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #56)
- F20-5: Transmission towers are insulated from the___ volts in the wires by porcelain insulators:
- T/F – The wires themselves are not insulated:
- 345,000.
* T – Wires are not insulated.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: The Power Distribution System (NC #57)
From a safe distance, look at any equipment that is attached to the line; it may be marked with the:
Normal operating voltage
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #58)
There are 2 main hazards from electricity:
Electrocution & burns
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #59)
Electrocution results from electrical currents interfering with:
The normal currents within the body – that cause the heart to contract & relax.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #61)
Electricity can cause paralysis of the muscles needed for breathing, resulting in asphyxiation, or the contraction of the muscles, forcing the body to:
- ‘Freeze’ in its position –
* Often in continuing contact with the conductor.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #62)
Electrocution is affected by several variables, the; (5):
- Amount of energy passing through body.
- The size of the contact point.
- The path E takes to enter/exit the body.
- The duration of the current flow.
- The condition of the skin (dry, wet or if the skin is broken).
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #63)
High-current flows though the body, either due to ___ or ___ cause rapid death:
- High-voltages -or-
* Low resistances (wet or broken skin).
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #64)
The amount of current flow through the body required to produce injury or death is very small. Table 20-1 → (NC 64-69):
1 milliamp = ___ of an amp:
1 milliamp (ma) = 1/1,000 of an amp
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #65)
Table 20-1 → Alternating current (AC) flow hazard to humans:
1 – 5 ma (results in):
Tingling sensation
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #66)
Table 20-1 → Alternating current (AC) flow hazard to humans:
5 - 10 ma (results in):
Pain
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #67)
Table 20-1 → Alternating current (AC) flow hazard to humans:
15 ma (results in):
Level where muscle contraction prevents letting go of a wire in the hand.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #68)
Table 20-1 → Alternating current (AC) flow hazard to humans:
> 50 ma (results in):
• Loss of muscle control.
• Cessation of the heart & respiratory functions.
• Death.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #69)
2 important factors that help determine whether a person survives a contact with electricity:
- The size of the contact point &
* The path electricity takes through the body to ground.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #70)
Current that enters or exits through the head directly impacts:
The brain and nervous system
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #71)
Current that enters one side of the body and traverses the chest to exit is likewise severe, as it impacts:
The heart & other vital organs
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #72)
Current that enters an extremity & exits before it travels the length of that extremity could result in less injury to the ___ organs:
Systemic organs
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #73)
Systemic organs include:
- Heart
- Lungs
- Brain
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #74)
Current that enters an extremity & exits before it travels the length of that extremity could result in less injury to the systemic organs, but could still produce a ___ that could be life threatening:
Severe injury (explosive amputation)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electrical Hazards (NC #75)
Duration of contact also plays a role – A longer duration ___ will likely produce greater damage:
Current flow
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #76)
Electricity also causes burns – the current flowing through the body produces 1 type of burn. T or F → Direct contact & current flow are not necessary to cause severe injury:
True
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #77)
Burns can also result from an electrical arc. An arc occurs whenever:
An electrical circuit is interrupted
examples – turning a light switch on/off, a wire that touches the ground
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #78)
___ is a good example of the power of electric arc.
Arc welding
(being sufficient to melt steel & permit it to form a continuous pool to weld the 2 pieces of steel together as it passes)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #79)
It is usually the presence of a ___, or the result of it, that triggers the response of FFs:
Arc
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #80)
An arc is caused by:
Current trying to jump an opening to reach ground.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #81)
An arc is caused by the current trying to jump across an opening to reach ground. In high-voltage conductors, the current can jump ___ ft or more (cont. on NC):
3 ft or more
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #82)
An arc is caused by the current trying to jump across an opening to reach ground. In high-voltage conductors, the current can jump 3’ or more, depending on:
- Moisture content of the air,
- Electrical potential -and-
- Type of conductor.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #83)
(CFPC) – That is why all ladders and all other equipment must be kept at least ___ feet from overhead power lines.
10’
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #84)
The arc also produces ___ that can damage the skin and eyes:
Ultraviolet rays
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #85)
If an arc is occurring or is possible, avoid looking directly at the source, since permanent damage to the ___, similar to that which occurs with welding, can occur:
Eyes
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #86)
(Reason why) FFs & utility personnel are cautioned not to turn any light switches on or off or on at suspected gas leaks, as well as not pull battery cables at an auto accident where gasoline vapors are present:
- Arcs that occur in presence of a flammable atmosphere –
* Can ignite the flammable vapors.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #87)
An arc can generate enough heat to melt metal and spatter the liquid. ___ heat from the arc itself, or the hot metal droplets can ignite combustibles – resulting in a more common Class A type fire:
Radiant
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #88)
If 2 energized lines of different potential come in contact with one another – as may be the case w/ an uninsulated overhead line, or a deteriorated underground cable, ___ will usually occur:
An arc
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #89)
The space that an arc can jump varies with (3):
- The conductor,
- The air moisture -and-
- The amount of voltage.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #90)
An arc can occur between 2 downed lines if they are ___, or they can arc to ground:
They are close enough to each other
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Elements of the System That Affect FFs (NC #105)
The distribution of electricity includes a combination of:
- Transformers, with –
* High & low-power carriers (cont. on nc)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #91)
Static electricity can (also) create electric arcs. Static charges accumulate when 2 like substances:
- Create friction by passing one another in contact -or-
* While being separated.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #92)
(CFPC) – When the charged object is close enough to an uncharged object, and the ___ is reduced enough, a spark will jump the gap in an attempt to follow the laws of physics and neutralize the charge:
Air space insulation
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #93)
___ is 1 very common occurrence of static arcing:
Lightning
Can ignite structures & kill people who are in the path of the discharging current
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #94)
T / F → Static arcs, as those you build in your clothes are strong enough to ignite flammable liquids & gases:
True
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Electric Arcs (NC #95)
Static arcs, as those you build in your clothes are strong enough to ignite flammable liquids & gases. ___ permits the static charge to drain away as it is produced, thereby preventing the charge strong enough to create an arc:
Proper grounding
Ch. 20: Norman – Electrical Fires & Emergencies
(NC #96)
___ is the result of current being dissipated to ground as it travels from a source:
Voltage gradient
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Voltage Gradient (NC #97)
If high-voltage wire is in contact with the ground, or in a puddle, the current is being dissipated into:
The soil
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Voltage Gradient (NC #98)
If high-voltage wire is in contact with the ground, or in a puddle, the current is being dissipated into the soil. The soil dissipates at various rates depending on:
- Moisture content
- Soil type &
- Wiring within them.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Voltage Gradient (NC #99)
(CFPC) – At the point of contact, the amount of voltage that will be present will be very close to:
Whatever voltage the wire is delivering – farther away, from POC, less voltage will be present as more current is absorbed by the ground.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Voltage Gradient (NC #100)
F20-8: The voltage gradient from a downed high-voltage line radiates (how and from where):
- Outward –
- From the poc – but not necessarily evenly in an evenly spaced radius, bc;
- Differences in conductivity of the soil.
- (Damp locations have higher current flows than dry – flow increases as source is approached)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Voltage Gradient (NC #101)
A person approaching the scene will initially contact these lower voltage areas & receive increasing voltages as h/s gets closer. The nearer as person gets to the wire, the greater the ___ that is present between each step:
Differences in the amount of current
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Voltage Gradient (NC #102)
(CFPC) – If you get close enough, you may feel a:
Tingling sensation – as the current passes up 1 leg & then travels out the leg that is farther away from the source.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Voltage Gradient (NC #103)
If you get close enough, you may feel a ‘tingling sensation’ as the current passes up 1 leg & then travels out the leg that is farther away from the source. This danger sign is a warning that:
You are about to get a real shock
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Voltage Gradient (NC #104)
The difference in the amount of current flow increases dramatically as the source is approached. If you encounter the tingling sensation, immediately (actions):
- Stop your forward advance.
- If possible – lift 1 foot clear of the ground to interrupt the current flow.
- Hop away from area on 1 foot - until clear.
- DO NOT – grab any objects for support; as they may provide better ground through your body do your feet.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Elements of the System That Affect FFs (NC #105)
The distribution of electricity includes a combination of:
- Transformers, with –
* High & low-power carriers (cont. on nc)
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Elements of the System That Affect FFs (NC #106)
The distribution of electricity includes a combination of transformers with high and low-power carriers, arranged in ___ grid systems:
Series and parallel
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Elements of the System That Affect FFs (NC #107)
FD purposes – only concerned w/ the aspects of the system that will affect us, either through:
Fire potential or shock hazard
Ch. 20: Norman – Electrical Fires & Emergencies
Sec. Elements of the System That Affect Firefighters (NC #108)
Carriers vary in voltage potential, depending on the:
Stage of the transmission
Ch. 20: Norman – Electrical Fires & Emergencies
Sec. Elements of the System That Affect Firefighters (NC #109)
A transmission line voltage will likely exceed _____ volts.
8,000
Ch. 20: Norman – Electrical Fires & Emergencies
Sec. Elements of the System That Affect Firefighters (NC #110)
Distribution line voltage will carry potentials of ___ volts:
601 – 8,000 volts
Ch. 20: Norman – Electrical Fires & Emergencies
Sec. Elements of the System That Affect Firefighters (NC #111)
Low voltage potentials range up to and include ___ volts:
600
Ch. 20: Norman – Electrical Fires & Emergencies
Sec. Elements of the System That Affect Firefighters (NC #112)
Terminology used by utility companies can be misleading to the layperson. Even ‘low voltage’ can be fatal. As FFs are concerned, ___ carriers are to be considered potentially fatal, regardless of how they are described:
All distribution system carriers
Ch. 20: Norman – Electrical Fires & Emergencies
Sec. Elements of the System That Affect Firefighters (NC #113)
Voltage cannot always be determined by:
- The size of the line,
- Its position on the pole, -or-
- Its position in the manhole vault.
Ch. 20: Norman – Electrical Fires & Emergencies
Sec. Elements of the System That Affect Firefighters (NC #114)
The introduction of ___ & ___ now allow small diameter cable to carry higher voltage, so you cant use line to determine voltage:
- Alloys -and-
* Winding techniques.
Ch. 20: Norman – Electrical Fires & Emergencies
Sec. Elements of the System That Affect Firefighters (NC #115)
FDs are most often concerned with areas of the distribution system where ___ are made:
• Changes in voltages are made.
- Such as →
- Substations,
- Transformers,
- Junctions of cables that are found in manholes or overhead structures like utility poles.
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Operational Procedures & Strategies (NC #116)
The safety of the operating personnel is paramount. The tactical position is generally:
Defensive – until the power is shut down
Ch. 20: Norman – Electrical Fires & Emergencies
Section: Operational Procedures & Strategies (NC #117)
The need for an offensive attack is rare and will be only be justified if:
Human life is at stake