“ Excellence Through Training ”
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Firefighter Safety
Controlling the Utilities
Natural Gas
Electricity
DANGER
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Properties of Natural Gas
1
0
1971
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Properties of Natural Gas
Odorless – Colorless - Tasteless
Methyl Mercaptan is added to give it it’s
distinguishable “rotten egg” odor
Odorized natural gas is detectable at
concentrations significantly less than 1%
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Properties of Natural Gas
Non-Toxic
94% - methane
4% - ethane
Often listed as a “Hazardous Material” due to it’s
flammability, not it’s toxicity
Only through it’s ability to displace oxygen can it
pose an asphyxiation hazard
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Properties of Natural Gas
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Properties of Natural Gas
Natural Gas
0.7
Vapor Density
30% lighter than air
Air = 1
Will rise and collect near the ceiling
Propane
1. 567
Properties of Natural Gas
Flammable Limits
Too Rich
14%
4.5%
Too Lean
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Properties of Natural Gas
Heating Value
1,000 BTU per cubic foot
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Properties of Natural Gas
Combustion Products
Complete combustion = heat, carbon dioxide & water
vapor
Incomplete combustion = carbon monoxide
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Properties of Natural Gas
Ignition Temperature
Natural Gas - 1163º F
Propane - 957º F
Gasoline - 632º F
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Properties of Natural Gas
Natural Gas Supply
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Properties of Natural Gas
Comparisons
Approx. Range
of Flammability
(% mix with air)
Vapor Density
(Air = 1.0)
Approximate
Ignition
Temperature
Natural Gas
4.5 - 14.0
.70
1163ºF
Hydrogen
4.0 – 7.5
.07
1076ºF
Propane
2.2 – 9.5
1.56
957ºF
Butane
1.9 – 8.5
2.01
912ºF
Gasoline
1.4 – 7.6
3.00
632ºF
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Natural Gas Equipment
Distribution System
Type of System
Pressure
Transmission Line
300 – 1000 psig
(High Pressure)
Distribution Main
(High Pressure)
Distribution Main
(Modified High Pressure)
Distribution Main
(Low Pressure)
Service / Customer
Line
60 – 300 psig
5 – 60 psig
¼ psig
¼ psig
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Natural Gas Equipment
Distribution System
Each time the pressure is reduced, over
pressure protection is provided by a relief
valve or automatic shut off
A relief valve venting gas to the atmosphere is performing
its proper function and should never be cut off or
restricted until the gas company arrives and makes
corrections to the system
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Natural Gas Equipment
Piping
Material
Color
Size
Pressure
Bare Steel
------
2” – 6”
Up to 60 psi
Wrapped
Steel
Yellow /
brown
½” – 20”
Up to 1000
psi
Wrought
Iron
------
2” – 6”
Up to 60 psi
Polyethylene
Plastic
Black /
orange /
yellow
½” – 6”
Up to 60 psi
Cast Iron
------
4” – 20”
¼ psi
Copper
------
¼ ” - ½”
¼ psi
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Natural Gas Equipment
Piping
POLYETHYLENE PIPE
Polyethylene pipe is buried with a 12 gauge
wire for ease of locating – it has nothing to do
with grounding or bonding
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Natural Gas Equipment
Piping
Distribution piping is normally buried
between 12” and 18” below ground level
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Natural Gas Equipment
Shut-off Valves
Square - Handle
T - Handle
L - Handle
Side View
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Natural Gas Equipment
Shut-off Valves
Closed Position
Open Position
Top View
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Natural Gas Equipment
Typical Residential Installation
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Natural Gas Equipment
Typical Residential Installation
Regulator
Relief Valve
Valve
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Natural Gas Equipment
Typical Residential Installation
Meter
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Natural Gas Equipment
Commercial Installation
Regulator
Meter
Valve
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Natural Gas Emergencies
Types of Emergencies
Odors / Leaks
Fire
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Natural Gas Emergencies
Emergency Response
Inside
Odors / Leaks
1) Approach incident from upwind, if possible.
2) Position apparatus at least 150” from scene.
3) Investigate for the source of the odor with the GasTrac
& Mini-Gas.
WCB prohibits entry into a confined space having an atmosphere
containing over 10% LEL combustible gas
4) If a strong odor is encountered or leak is confirmed,
evacuate the bldg. of all occupants.
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Natural Gas Emergencies
Emergency Response
Inside
Odors / Leaks
5) Notify BC GAS - Gas Op's to respond.
6) Ventilate the bldg. by opening doors & windows.
Remember to open windows on top.
7) Do not operate electrical switches / telephones.
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Natural Gas Emergencies
Emergency Response
Inside
Odors / Leaks
8) Use only intrinsically safe radios / handlights.
9) If a leak is confirmed, the IC should determine if it can
be stopped or if the gas needs to be shut off at the valve.
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Natural Gas Emergencies
Emergency Response
Inside
Odors / Leaks
10) Hand tools should be spark-proof
(1663 / 1665).
11) Gas valves turned OFF by FD personnel SHOULD
NEVER be turned back on without BC GAS - Gas Op's
on scene.
12) No one should re enter the bldg. until BC GAS - Gas
Op's has secured the leak and determined that it is safe
to enter.
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Natural Gas Emergencies
Emergency Response
Outside
Odors / Leaks
1) If unignited gas is escaping from the ground, either from
an excavation site or from an open pipe outside of a
bldg., notify BC GAS - Gas Op's immediately.
2) Establish a safe area around the incident scene.
3) Extinguish all open flames.
4) Check surrounding bldgs., especially basements, for the
presence of gas.
Gas can migrate through the ground, following pipes or natural
stratifications in the earth.
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Natural Gas Emergencies
Emergency Response
Outside
Odors / Leaks
5) Restrict or re-route traffic until BC GAS - Gas Op's
personnel can bring the gas flow under control.
6) Although water fog streams can be used to disperse
escaping vapors, they are usually ineffective since the
lighter-than-air gas naturally rises.
7) If water fog is used, caution must be exercised to avoid
filling excavation sites with water.
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Natural Gas Emergencies
Emergency Response
Outside
Odors / Leaks
8) FD personnel should never clamp or crimp a gas line.
Static electricity could ignite escaping gas, resulting in a
sudden and violent ignition.
9) Hand tools should be spark-proof
(1663 / 1665).
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Natural Gas Emergencies
Emergency Response
Fires
Inside
1) Notify BC GAS - Gas Op's immediately upon receipt of
alarm.
2) The IC should determine if the gas can safely be shut off
inside the bldg. or at the meter.
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Natural Gas Emergencies
Emergency Response
Fires
Inside
3) In certain industrial / commercial settings, turning off the
gas supply can seriously interrupt important and costly
industrial processes and should only be done upon
evaluation with company personnel and BC GAS - Gas
Op's.
4) If the gas supply cannot be shut off, the surrounding
combustibles should be kept wet with a fog stream.
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Natural Gas Emergencies
Emergency Response
Outside
Fires
1) Notify BC GAS - Gas Op's immediately upon receipt of
alarm.
2) The best method of controlling outdoor gas fires is to
shut off the gas flow.
3) In most cases, FD personnel should not attempt to
extinguish the fire while the gas is still escaping.
4) BURNING GAS WILL NOT EXPLODE.
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Natural Gas Emergencies
Emergency Response
Outside
Fires
5) Secure the area and protect exposures, if necessary.
6) IF it is necessary to extinguish the fire before the gas
flow can be stopped, use a Dry Chem extinguisher
aimed at the base of the flame and wet the surrounding
area with water fog to prevent the re-ignition of
combustibles.
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Electrical Emergencies
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Electrical Hazards
Distribution System
Primary Lines
Secondary Lines
Transformer
Cable TV /
Telephone Lines
Insulators
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Electrical Hazards
Distribution System
Primary Lines
- located at the highest level of the pole
- carry the greatest amount of power
- normally bare wire, which gives them
the “look” of support cables
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Electrical Hazards
Distribution System
Secondary Lines
- located one level below the primary
lines, at the second-highest level of the
pole.
- carry voltages less than primaries.
- may be coated for protection from the
elements. This coating DOES NOT
provide insulation from live current.
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Electrical Hazards
Distribution System
Cable TV / Telephone Lines
- located at the lowest level of the pole
- carry lower voltages than primaries & secondaries
- should be coated for protection from the elements. This
coating DOES NOT guaranty insulation from live current.
- should always be considered dangerous due to backfeeding or cross-conduction.
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Electrical Hazards
Types of Emergencies
Downed Wires
Pole / Transformer Fires
Vehicle / Pole Accidents
Wires on Vehicle
Vehicles Contacting Wires
Manhole Fires
Substations
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CAUTION
CAUTION
CAUTION
CAUTION
Electrical Hazards
Step Potential
The voltage decreases as the distance
from the point of contact increases
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Electrical Hazards
Types of Emergencies
Downed Wires
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Electrical Hazards
Types of Emergencies
Downed Wires
Always treat all downed wires, including Cable TV &
telephone wires, as energized at high voltage until proven
otherwise.
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Electrical Hazards
Types of Emergencies
Downed Wires
• It is impossible to determine if a wire is energized by its
appearance.
• Never attempt to move or cut any downed conductors.
Remember, wooden or fiberglass pike poles MAY BE
conductive.
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Electrical Hazards
Types of Emergencies
Upon arrival
Downed Wires
• Establish a safety zone and secure the area.
• If possible, the safety zone should extend a minimum of
two full span lengths of wire in each direction beyond the
downed wire.
- poles may break and fall due to stress
- wires can slip through insulators and sag to the ground
- wire may be contacting metal fences, guard rails,
buildings, etc.
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Electrical Hazards
Types of Emergencies
Downed Wires
Safety Zone
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Electrical Hazards
Types of Emergencies
Downed Wires
• Any high-voltage wire, when disturbed, can get out
of control.
• FF boots do not guaranty insulation from energized
wires.
• NO HIGH VOLTAGE wire is insulated. The coating
sometimes seen is to provide protection from the
elements.
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Electrical Hazards
Types of Emergencies
Downed Wires
• Bodies in contact with live wires may be energized.
DO NOT TOUCH the individual until the wire is
tested dead and cleared form the body.
• Wires should not be assumed dead until they are
tested dead or certain assurance from BC HYDRO
personnel is rec’d.
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Electrical Hazards
Types of Emergencies
Pole / Transformer Fires
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Electrical Hazards
Types of Emergencies
Pole / Transformer Fires
• If a downed wire is involved in the fire, use a fog
pattern to keep the fire in check and protect the
surrounding area.
• If the fire is at the top of the pole, or is on pole-mounted
equipment, and it appears that the fire will not endanger
life or property, let it burn. Remember, once electrical
equipment is involved in fire, it is not salvageable.
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Electrical Hazards
Types of Emergencies
Pole / Transformer Fires
• In the rare case where the fire must be attacked and/or
the equipment has not been de-energized, exercise
extreme caution.
• Most pole fires are caused by:
– lightning
– insulator breakdown (broken or contaminated by
salt spray or air pollution)
– equipment failure
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Electrical Hazards
Types of Emergencies
Pole / Transformer Fires
• As most pole-mounted equipment contains oil, the
extinguishing agents of choice are dry chemical and water
fog.
• If the equipment is still energized, little can be done to
extinguish the fire, as the oil will continue to re-ignite.
• When in doubt, secure the area, establish a safety zone
and allow BC HYDRO to arrive and determine the safe
and proper course of action.
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Electrical Hazards
Types of Emergencies
Vehicle / Pole Accidents
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Electrical Hazards
Types of Emergencies
Vehicle / Pole Accidents
• All potential hazards should be thoroughly evaluated.
• Approach cautiously - Establish a safety zone.
• If a fire is present, use a fog pattern rather than straight
stream.
•Remember: the vehicle and anything attached to it may be
energized.
•Approach the vehicle to no closer than 10 feet.
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Electrical Hazards
Types of Emergencies
Vehicle / Pole Accidents
•Occupants have one overriding thought . . . . To get out of the
vehicle.
• Gain their confidence and order them to remain in the
vehicle.
• In dire emergencies and under ideal conditions, the driver
can try to move the vehicle from underneath the wires.
• However, the wire may weld itself to the vehicle –
preventing movement.
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Electrical Hazards
Types of Emergencies
Vehicle / Pole Accidents
• If it is absolutely necessary to have the occupants exit the
vehicle, they should be given explicit instructions and told not
to come in contact with the vehicle and the ground at the same
time.
• Once on the ground, small shuffling steps should be taken to
move away from the involved vehicle (remember - step
potential).
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Electrical Hazards
Types of Emergencies
Vehicle / Pole Accidents
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Electrical Hazards
Types of Emergencies
Vehicle / Pole Accidents
In some cases, poles struck by a vehicle will sever, leaving
the top portion suspended in air by the wires.
In these cases, if energized wires are not contacting the
vehicle, the occupants should be evacuated and a secure zone
established.
The supported section may fail, causing energized wires to
fall to the ground.
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Electrical Hazards
Types of Emergencies
Vehicles contacting wires
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Electrical Hazards
Types of Emergencies
Vehicles contacting wires
Procedures for vehicles in contact with energized wires are the
same as those for vehicle / pole accidents.
The “step potential” affects the area around the involved
vehicle, as well.
Unless threatened by fire or some other danger, occupants
should remain on the vehicle until the wires can be deenergized.
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Electrical Hazards
Types of Emergencies
Vehicles contacting wires
The entire vehicle may be energized, causing tires and fluids to
burn, lug nuts to weld & other components to fail, especially
pressurized cylinders (bumpers / hatch lifts).
Fires should be extinguished with a fog pattern – NOT a
straight stream.
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Electrical Hazards
Types of Emergencies
Manhole Fires
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Electrical Hazards
Types of Emergencies
Manhole Fires
Notify BC HYDRO and BC GAS immediately upon
receipt of the alarm.
•
• Secure the area. Establish a safety zone.
• If the cover is in place, do not attempt to remove it
without first consulting with BC HYDRO and BC GAS
personnel.
– If flammable gases are present, removing the cover
may provide sufficient air to cause an explosion.
– If a transformer has failed and the oil is above it’s
ignition temperature, removing the cover may cause a65
backdraft.
Electrical Hazards
Types of Emergencies
Manhole Fires
A spark resulting from removing the cover may cause
an explosion of gases in the manhole.
•
• If there are gases present in the ductwork running from
manhole-to-manhole, subsequent explosions could occur
down the line.
• Explosions have been known to propel a manhole cover
(which weigh approx. 270 lbs.) a significant distance.
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Electrical Hazards
Types of Emergencies
Manhole Fires
If the manhole cover is already off, do not enter the
manhole or take any further action until the situation has
been evaluated by BC HYDRO and BC GAS personnel.
•
• Manholes must always be treated as highly hazardous
confined spaces.
• Except for rescue, FD personnel should never enter a
manhole.
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Electrical Hazards
Types of Emergencies
Manhole Fires
REMEMBER
Unless there is
human life at stake,
there is no great
urgency to extinguish
a fire or enter the
manhole. Maximum
damage to the
equipment has
already taken place.
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Electrical Hazards
Types of Emergencies
Substations
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Electrical Hazards
Types of Emergencies
Substations
Hazards
• High voltage (overhead & underground)
• Open high-voltage work
• Oil-filled switch gear, transformers, etc.
• Toxic smoke & gases due to burning oil & insulating materials
• Intense heat of a fire can collapse steel framework
• Explosion from oil-filled equipment
• Exploding glass & porcelain insulators
• Falling wires
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Electrical Hazards
Types of Emergencies
Substations
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Electrical Hazards
Types of Emergencies
Substations
• FD personnel should not enter substations, either
private or BC HYDRO, unless accompanied by BC
HYDRO.
• Any electrical apparatus, transformer or switch that
has been on fire cannot be salvaged.
• Efforts should be directed at protecting surrounding
property and awaiting arrival of BC HYDRO.
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Electrical Hazards
Types of Emergencies
Substations
• Some equipment, such as circuit switches and breakers,
have porcelain housings that are pressurized with SF-6
gas. If they are involved in fire and sprayed with water,
the sudden temperature change may cause a violent
failure.
• Never operate electric utility high-voltage switches that
are within a substation property, mounted on poles, or
located within manholes or vaults. Many of these are not
designed to drop electric load.
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Electrical Hazards
Structure Fires
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Electrical Hazards
Structure Fires
It is usually best to leave the power on to structures as
long as you safely can
When safe firefighting tactics require the power to be shut
off, the following actions are appropriate:
 de-energize the fire-affected area by removing fuses or opening
circuit breakers.


open the main disconnects to de-energize the entire bldg.
if the bldg. is damaged to the extent that service is no longer req’d
or puts personnel in jeopardy, the service to the bldg. should be
disconnected by BC HYDRO
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Electrical Hazards
Structure Fires
Meters
BC HYDRO says . . .
Never pull an electric
meter to de-energize a
bldg.
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Electrical Hazards
Structure Fires
Meters
Reasons for NOT removing meters
1) Pulling the meter may not de-energize the electric service to the
bldg.
~
Services over 200 amps are metered by current transformers.
Pulling the meter will not shut off the electric supply.
~
Some meter bases are equipped with automatic bypasses. When
the meter is removed, the bypasses close and the bldg. remains
energized.
~
People have developed many unique methods to bypass the
meter.
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Electrical Hazards
Structure Fires
Meters
Reasons for NOT removing meters
2) If there is a presence of explosive gases in the bldg., the service wire
piping can act like a chimney. A small amount of gas may be present
in the meter socket and pipe. When the meter is removed, a small
arc will occur and the gas may explode.
3) If the meter is exposed to the heat of the fire, it can build up internal
stresses and explode on contact.
4) After a meter is removed, the energized contacts in the meter socket
are left exposed, posing a shock hazard to anyone near the meter
base.
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Electrical Hazards
Summary
Treat all wires as dangerous and energized at high voltage
until tested and proven otherwise.
Exercise extreme caution when approaching the scene,
especially at night.
Establish a safety zone and prevent all unauthorized
persons from approaching the scene.
Secure the scene until relieved by BC HYDRO.
Never tamper with energized wires or equipment.
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Electrical Hazards
Summary
Your primary responsibility is to save lives . . .
including your own.
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