1 electrical safety- related work practices in and around the mines and the home
TRANSCRIPT
1
Electrical Safety-Related Work Practices
In and around the mines
AND
The home
3
WHAT IS ELECTRICITY??
4
?
Electricity is a form of energy High Voltage (>650 volts) Low Voltage (650 volts or less) Alternating Current Direct Current Static Electricity
5
6
7
8
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
Let’s 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 deathsSwitches and outlets are involved in 4,700 fires and deaths
11
Coal-Underground 752 Coal-Surface 137 Metal/non-metal-Underground 99 Metal/non-metal-Surface 655 Prep Plants 244 Other 34
Total 1921
Reported Mining Electrical Accidents (INCLUDES FATALITIES) 1990 thru 2000
12
Fatal Electrical Accidents1990 thru 2000
• Coal-UndergroundCoal-Underground 27 27
• Coal-SurfaceCoal-Surface 4 4
• Metal/non-metal-UndergroundMetal/non-metal-Underground 7 7
• Metal/non-metal-SurfaceMetal/non-metal-Surface 29 29
• Prep PlantsPrep Plants 9 9
• OtherOther 2 2
TotalTotal 78 78
But more important is the cost in lives……
13
Causes of Electrical Injuries
Touching live parts.
Short circuit
Accidental ground
Overload
14
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
21
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.
Electrical Shock
22
Electrical Shock
The amount of current that flows through the victim’s 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 systemsourcesconductorsloadsswitches
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
•Current = flow
•Resistance = system resistance to flow
•Voltage = pressure
29
Ohms Law
amps
• Since voltage is constant,
current flow depends on resistance
voltageresistance
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 person’s feet Touch potential
Difference in voltages between points of contact (usually hands and/or feet)
HOW DO WE PROTECT OURSELVES????
LOCK OUT-
TAG OUT!!
35
LOCKOUT/TAGOUTTypes of Devices
36
LOCKOUT/TAGOUTTypes of Energy
MechanicalHydraulicPneumaticChemicalThermalOther
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)
HOW ELSE CAN WE PROTECT OURSELVES???
BY USING GFCI’S
40
How does the GFCI workHow does the GFCI work GFCIs constantly monitor electricity GFCIs constantly monitor electricity flowing in a circuit. flowing in a circuit.
If the electricity flowing into the circuit If the electricity flowing into the circuit differs by even a slight amount from differs by even a slight amount from that returning, the GFCI will quickly that returning, the GFCI will quickly shut off the current flowing through that shut off the current flowing through that circuit. circuit.
The advantage of using GFCIs is that The advantage of using GFCIs is that they can detect even small variations in they can detect even small variations in the amount of leakage current, even the amount of leakage current, even amounts too small to activate a fuse or amounts too small to activate a fuse or circuit breaker. circuit breaker.
GFCIs work quickly, so they can help GFCIs work quickly, so they can help protect consumers from severe electric protect consumers from severe electric shocks and electrocution.shocks and electrocution.
41
Some things a GFCI does not protect you from. Some things a GFCI does not protect you from.
A GFCI does not protect a person who comes in contact with two A GFCI does not protect a person who comes in contact with two hot wires or any hot wire and the neutral wire.hot wires or any hot wire and the neutral wire.
A GFCI does not protect a person from feeling and reacting to A GFCI does not protect a person from feeling and reacting to shockshock
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
DON’T 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!!!