Electrical Safety-Related Work Practices

1
Electrical Safety-Related Work Practices

• In and around the mines
• AND
• The home

2
Jon Montgomery, EFSmontgomery.jon_at_dol.gov

• Albany, NY
• 518-489-0780

3
WHAT IS ELECTRICITY??
4
?

• Electricity is a form of energy
• High Voltage (gt650 volts)
• Low Voltage (650 volts or less)
• Alternating Current
• Direct Current
• Static Electricity

5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
ELECTRICAL ACCIDENTS

• Electrocutions rank fourth in work related
  fatalities with about half of these at 600 volts
  or less.
• There are an average of over 3,600 disabling
  electrical related injuries annually.
• There are an average of 4,000 non-disabling
  electrical injuries annually.

10
Lets talk about personal protection and the home

• 40,000 residential fires annually which are
  caused by problems with electrical wiring
  systems, claiming more than 350 lives
• Additionally, electric cords and plugs were
  involved in about 7,100 fires resulting in 120
  deaths or about 32 of all deaths associated with
  residential electrical system fires, occurring
  each year.
• Lamps and light fixtures were involved in about
  8,900 fires and 60 deaths
• About 3,600 people are treated for injuries
  associated with extension cords.

Switches and outlets are involved in 4,700 fires
and deaths
11
Reported Mining Electrical Accidents
(INCLUDES FATALITIES) 1990
thru 2000

• Coal-Underground 752
• Coal-Surface 137
• Metal/non-metal-Underground 99
• Metal/non-metal-Surface 655
• Prep Plants 244
• Other 34
• Total 1921

12
Fatal Electrical Accidents1990 thru 2000
But more important is the cost in lives

• Coal-Underground 27
• Coal-Surface 4
• Metal/non-metal-Underground 7
• Metal/non-metal-Surface 29
• Prep Plants 9
• Other 2
• Total 78

13
Causes of Electrical Injuries

• Touching live parts.

Short circuit
Accidental ground
Overload
14
(No Transcript)
15
Electrical Hazards

• Exposed conductors
• Frayed and worn insulation
• Exposed bus bars and connections
• Overloaded circuits
• Modified circuits
• Removed grounding plug
• Jury-rigged connections

16
Effects on the Body

• Burns
• Flash burns (from electrical arcs)
• Electrical burns (entry exit wounds)
• Electrical Shock
• Damage to internal organs and body systems

17
Effects on the Body

• Approximately 50 volts is needed to overcome skin
  resistance

Resistance is higher on dry skin
Resistance is lower on wet skin
18
ENTRY WOUND
19
EXIT WOUND
20
(No Transcript)
21
Electrical Shock

• A person receives an electrical shock whenever
  any part of his/her body becomes part of the
  electrical circuit through which a sufficient
  current flows to cause discomfort or worse.
• Current flow slightly above this threshold is
  sufficient to cause discomfort
• May cause involuntary contraction of the muscles.
• Stop the heart.
• Stop breathing.
• Cause burns.

22
Electrical Shock

• The amount of current that flows through the
  victims body will depend on
• The voltage of the circuit with which he/she is
  in contact.
• The insulating qualities of the place in which
  he/she is located at the instant.
• The resistance of skin or clothing or both.
• The area of contact with the live conductor.
• The pressure of contact with the live conductor.
• The area of contact with the live conductor

23
four major components of an electrical system

• sources
• conductors
• loads
• switches

24
SOURCES

• provide electricity
• batteries
• transformers
• generators
• water system equivalent - water tank

25
CONDUCTORS

• carry electricity
• wires
• cables
• bus bars
• water equivalent - pipes

26
LOADS

• use electricity
• motors
• pumps
• fans
• hand tools
• lights
• heaters
• water equivalent -water wheel

27
SWITCHES

• control electricity
• floats
• push buttons
• disconnects
• duplex outlets / plugs
• water equivalent - valves

28
Water system comparison

• Voltage pressure

• Current flow

• Resistance system resistance to flow

29
Ohms Law
amps
voltage
resistance

• Since voltage is constant,
• current flow depends on resistance

30
30 CFR 56/57. 12028

• 56/57.12028 Testing grounding systems.
• Continuity and resistance of grounding systems
  shall be tested immediately after installation,
  repair, and modification and annually
  thereafter. A record of the resistance measured
  during the most recent tests shall be made
  available on a request by the Secretary or his
  duly authorized representative.

31
Equipment grounding systems

• high resistance low current
• low resistance high current
• current flow is what trips fuses/breakers

32
Be sure

• all grounds ohms values are as low as possible
• all wiring connections are clean tight
• all conduit connections are clean tight
• all plugs have ground prong in place

33
Methods of Contact

• Step potential
• Difference in voltages (potential for current
  flow) between persons feet
• Touch potential
• Difference in voltages between points of contact
  (usually hands and/or feet)

34
HOW DO WE PROTECT OURSELVES????

• LOCK OUT-
• TAG OUT!!

35
LOCKOUT/TAGOUTTypes of Devices
36
LOCKOUT/TAGOUTTypes of Energy

• Mechanical
• Hydraulic
• Pneumatic
• Chemical
• Thermal
• Other

37
LOCKOUT/TAGOUTPreparation for Shutdown

• Know the types and amounts of energy that power
  it.
• Know the hazards of that energy.
• Know how the energy can be controlled.

38
VERIFY-VERIFY-VERIFY!!!! (ONLY IF YOU ARE
QUALIFIED)
39
HOW ELSE CAN WE PROTECT OURSELVES???

• BY USING GFCIS

40

• How does the GFCI work
• GFCIs constantly monitor electricity flowing in a
  circuit.
• If the electricity flowing into the circuit
  differs by even a slight amount from that
  returning, the GFCI will quickly shut off the
  current flowing through that circuit.
• The advantage of using GFCIs is that they can
  detect even small variations in the amount of
  leakage current, even amounts too small to
  activate a fuse or circuit breaker.
• GFCIs work quickly, so they can help protect
  consumers from severe electric shocks and
  electrocution.

41
Some things a GFCI does not protect you from. A
GFCI does not protect a person who comes in
contact with two hot wires or any hot wire and
the neutral wire. A GFCI does not protect a
person from feeling and reacting to shock
42
ALWAYS REMBER! Never work on a Energized Circuit.
Unless you are trained to. Always Lock and
Tag Never depend on another person to take the
power off a circuit that you are going to work
on. Its your Life! This should even apply to
home. Just remember that Half of what you have
is hers.
43
Qualified Employees

• One knowledgeable in the construction and
  operation of the electric power generation,
  transmission, and distribution equipment
  involved, along with the associated hazards.
• Qualified employees must have training to be
  considered qualified.

44
Qualified Employees

• Qualification extends to individual tasks
• Employees can be qualified in one task, but not
  in another.
• Examples
• Racking breakers in out
• Changing fuses
• Substation switching

45
Unqualified Employees

• Unqualified employees and mobile mechanical
  equipment must maintain a safe distance from
  energized circuits
• Overhead power lines
• Unguarded, exposed, energized conductors
• 10 feet up to 50,000 volts
• Additional 4 inches for every 10,000 volts over
  50 kV

46
Methods of Protection

• Insulation
• Verify insulation is intact
• Pay particular attention to flexible cords, such
  as extension cords and tool power cords

47
Methods of Protection

• Guarding
• Live parts operating at 50 volts or more must be
  guarded
• Locate in a room or vault accessible only by
  qualified persons
• Permanent partitions or walls
• Metal-clad switchgear required if over 600 volts
• Distance
• 8 feet (or more) above the floor
• Warning Signs

48
Methods of Protection

• Grounding
• Service ground
• Neutral conductor is grounded
• Equipment ground
• Frame or casing of tool or equipment is wired
  directly to ground.

49
Methods of Protection

• Circuit Protection Devices
• Fuses and Circuit Breakers
• Designed for equipment protection
• Open circuit on high current
• GFCI
• Ground Fault Circuit Interrupter
• Designed for personnel protection
• Opens quickly (1/40 second) on any ground fault

50
Methods of Protection

• Safe Work Practices
• De-energize
• Lockout/Tagout energy sources
• Use electric tools that are in good repair
• Do not perform work you are not qualified for
• Use appropriate protective equipment
• FR clothing, non-conductive hard hats, rubber
  mats, line hose, hot sticks, rubber gloves,
  safety glasses, face shields, etc.

51
Methods of Protection

• Overhead Lines
• Only qualified employees can work on or near
• All others maintain 10-foot rule, or
• Owner/operator must de-energize and ground lines
  prior to work

52
Safe Work Practices

• DO
• Inspect cords for damage
• De-energize and L.O.T.O.
• Keep cords off walkways
• Wear PPE
• Perform work only if qualified
• Use a GFCI

• DONT
• Overload plugs
• Upsize fuses, or use substitutes
• Lay cords in water
• Use defective equipment
• Assume household current is safe
• Use conductive ladders

53
IF SOMEONE CONTACTS AN ENERGIZED CONDUCTOR
----WHAT SHOULD ONE DO ??
54
BLOOD TESTS TO WARN OF FIBRILLATION TO OCCUR

• TROPONIN
• CPK ISOENZYME
• (CREATINE KINASE)

55
PLEASEREMEMBER---
56
SAFETY FIRST!!!!
57

• THANK YOU ALL FOR LISTENING!!!