Excellence Through Training

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Excellence Through Training
February, 2000
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Firefighter Safety
Controlling the Utilities
Natural Gas
Electricity
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Properties of Natural Gas
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Properties of Natural Gas
Odorless Colorless - Tasteless
Methyl Mercaptan is added to give it its
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 its flammability,
not its toxicity Only through its 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
Vapor Density
30 lighter than air
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Properties of Natural Gas
Flammable Limits
Too Rich
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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
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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 (High Pressure) 300 1000 psig
Distribution Main (High Pressure) 60 300 psig
Distribution Main (Modified High Pressure) 5 60 psig
Distribution Main (Low Pressure) ¼ psig
Service / Customer Line 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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POLYETHYLENE PIPE
Natural Gas Equipment
Piping
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
Side View
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Natural Gas Equipment
Shut-off Valves
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
Meter
Regulator
Valve
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Natural Gas Emergencies
Types of Emergencies
Odors / Leaks Fire
Outside Building
Inside Building
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Natural Gas Emergencies
Emergency Response Odors / Leaks

• Inside
• Approach incident from upwind, if possible.
• Position apparatus at least 150 from scene.
• Investigate for the source of the odor with the
  GasTrac Mini-Gas.
• COMM 32 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 Odors / Leaks
Inside 5) Notify WEPCO - 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 Odors / Leaks

• Inside
• 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 Odors / Leaks
Inside 10) Hand tools should be spark-proof
(1663 / 1665).
11) Gas valves turned OFF by FD personnel
SHOULD NEVER be turned back on without WEPCO -
Gas Op's on scene. 12) No one should re enter
the bldg. until WEPCO - Gas Op's has secured the
leak and determined that it is safe to enter.
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Natural Gas Emergencies
Emergency Response Odors / Leaks

• Outside
• If unignited gas is escaping from the ground,
  either from an excavation site or from an open
  pipe outside of a bldg., notify WEPCO - Gas Op's
  immediately.
• Establish a safe area around the incident scene.
• Extinguish all open flames.
• 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 Odors / Leaks
Outside 5) Restrict or re-route traffic until
WEPCO - 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 Odors / Leaks

• Outside
• FD personnel should never clamp or crimp a gas
  line. Static electricity could ignite escaping
  gas, resulting in a sudden and violent ignition.
• Hand tools should be spark-proof (1663 /
  1665).

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Natural Gas Emergencies
Emergency Response Fires

• Inside
• Notify WEPCO - Gas Op's immediately upon receipt
  of alarm.
• 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 WEPCO - 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 Fires

• Outside
• Notify WEPCO - Gas Op's immediately upon receipt
  of alarm.
• The best method of controlling outdoor gas fires
  is to shut off the gas flow.
• In most cases, FD personnel should not attempt to
  extinguish the fire while the gas is still
  escaping.
• BURNING GAS WILL NOT EXPLODE.

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Natural Gas Emergencies
Emergency Response Fires
Outside 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
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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
  back-feeding 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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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 Downed Wires

• Upon arrival
• 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 WEPCO
  personnel is recd.

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Electrical Hazards
Types of Emergencies
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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 WEPCO to arrive and
  determine the safe and proper course of action.

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Electrical Hazards
Types of Emergencies
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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
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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 de-energized.
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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 WEPCO 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 WEPCO
  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 its ignition temperature, removing the
  cover may cause a backdraft.

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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 WEPCO
  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 WEPCO, unless accompanied by
  WEPCO or private industry personnel.
• 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
  WEPCO.

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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 reqd or puts personnel in
  jeopardy, the service to the bldg. should be
  disconnected by WEPCO.

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Electrical Hazards
Structure Fires
Meters
WEPCO 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
• 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
• 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.
• If the meter is exposed to the heat of the fire,
  it can build up internal stresses and explode on
  contact.
• 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
WEPCO. Never tamper with energized wires or
equipment.
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Electrical Hazards
Summary
Your primary responsibility is to save lives . .
. including your own.