Electrical Safety Program

Electrical Safety Program

Overview Describe identified hazards
Ensure personnel have required PPE while working on energized circuits Identify common hazards with electrical equipment Submit work request to address hazards Documentation of hazards

Basic Electrical Terminology
Current: the movement of electrical charge Resistance: opposition to current flow measured in ohms Voltage: a measure of electrical force Conductors: substances, such as metals, that have little resistance to electricity Insulators: substances, such as wood, rubber, glass, and bakelite, that have high resistance to electricity Grounding: a conductive connection to the earth which acts as a protective measure Resistance - Dry skin has a fairly high resistance, but when moist, resistance drops radically, making it a ready conductor.

Background Operating an electric switch is like turning on a water faucet. For electricity, the source is the power generator. Current travels through electrical conductors (wires) and the force to make it flow, measured in volts, is provided by the generator. Behind the faucet or switch there must be a source of water or electricity with something to transport it, and with a force to make it flow. In the case of water the source is a pump, and the force to make it flow through the pipes is provided by the pump.

Background cont. VOLTAGE
We will cover in later slides what an ampere and ohm is and how it relates to a volt. Volt - The unit of measure of the pressure required to force one ampere through a resistance of one ohm.

Difference Of Potential
Pressure Voltage is a measurement of electrical pressure or the difference of potential. When the valve is open on the pipe between the tanks water will flow until both tanks are balanced. When we look at the two tanks to right we see the tank to the left was filled with water and the one to the right is empty. There is a difference of potential between the two tanks.

Difference Of Potential
Balanced Pressure Voltage is a measurement of electrical pressure or the difference of potential. When the valve is open on the pipe between the tanks water will flow until both tanks are balanced. Once both tanks contain equal amounts of water, the flow of water will stop. Electricity behaves in a similar manner.

Watt: Background cont. A measure of the total energy
flowing in a circuit at any given moment. A measure of electric power.

Background cont. Good example of watts as “Power” can be seen when energy is converted to heat. The more wattage the more heat!

Background cont. Amps We will cover what an ohm is later in this training. Ampere - The unit of measure of electric current which will flow through one ohm under a pressure of one volt.

Background cont. Current Flow
The water current or flow can be measured in gallons per minute. Electrical current is like water flowing through a pipe Electrical current is measured in amperes

Background cont. Wire is a good conductor of electrical current. Wire offers some resistance to the flow of electrical current The factors that affect the resistance of the wire are: The length The diameter The type of manufacturing material The operating temperature The longer the wire the more resistance Wire with a larger diameter offers less resistance then wire with a smaller diameter Wire that is made of copper offers less resistance then aluminum wire The higher the temperature the more resistance

Background cont. Pipe A Pipe B
Likewise, a long wire carrying electrical current causes a reduction in electrical pressure or what is called a voltage drop. Compare the sets of tanks above. Pipe “B” is longer than Pipe “A”. Pipe “B” will offer more resistance to the flow of water. This will result in a lost of pressure. In electricity, this is called a voltage drop.

Background cont. Pipe A Pipe B
This will result in a lost of pressure in Pipe “A”. Likewise, a smaller diameter wire carrying electrical current causes a reduction in electrical pressure or what is called a voltage drop. Compare the sets of tanks above. Pipe “B” is larger than Pipe “A”. Pipe “B” will offer less resistance to the flow of water.

Background cont. Resistance is measured in ohms
Pressure Current Flow One Volt One Ohm One Ampere Resistance is measured in ohms An ohm is a unit of measure of resistance through which one volt will force one ampere

Background cont. P E Wattage Volts I I R E Amps Amps Volts E

Training (29 CFR ) All qualified and unqualified (electrical) workers in jobs that face the risk of electric shock that is not reduced to a safe level by the electrical insulation must receive classroom or on-the-job training in safety-related work practices that pertain to their respective job assignments Additional requirements for unqualified workers Any electrically related safety practices that are necessary for their safety

Training (29 CFR ) cont. Additional requirements for qualified workers (those permitted to work on or near exposed energized parts) The skills and techniques necessary to: Distinguish exposed live parts from other parts of electrical equipment Determine the nominal voltage of exposed live parts Determine the clearance distances and the corresponding voltages to which they will be exposed OSHA’s electrical safety-related work practice requirements are contained in 29 CFR 1. Deenergizing Electrical Equipment. The accidental or unexpected sudden starting of electrical equipment can cause severe injury or death. Before ANY inspections or repairs are made the current must be turned off at the switch box and the switch padlocked in the OFF position. At the same time, the switch or controls of the machine or other equipment being locked out of service must be securely tagged to show which equipment or circuits are being worked on. For more information on the Lockout/Tagout (LOTO) standard, , see the Lockout/Tagout Interactive Training Program at the osha web site, and find this reference under “OSHA Advisors”.

Describe identified hazards
There are four main types of electrical injuries: Electrocution (death due to electrical shock) Electrical shock Burns Falls

If electrocution occurs Call for help DO NOT touch the victim or the conductor Shut off the current at the control box If the shutoff is not available, use a non-conducting material to free the victim If necessary and you know how, begin CPR when current is stopped In dealing with electricity, never exceed your expertise

Electrical Shock Received when current passes through the body Severity of a shock depends on: Path of current through the body Amount of current flowing through the body Length of time the body is in the circuit

Dangers of Electrical Shock Currents greater than 75 mA* can cause ventricular fibrillation Will cause death in a few minutes unless a defibrillator is used Ventricular fibrillation - rapid, ineffective heartbeat 75 mA is not much current – a small power drill uses 30 times as much Defibrillator in use

Electrical Shock When two wires have different potential differences (voltages), current will flow if they are connected together In most household wiring, the black wires are at 110 volts relative to ground The white wires are at zero volts because they are connected to ground If you come into contact with an energized (live) black wire, and you are also in contact with the white grounded wire, current will pass through your body and YOU WILL RECEIVE A SHOCK Grounding is a physical connection to the earth, which is at zero volts. Electricity travels in closed circuits, and its normal route is through a conductor. Electric shock occurs when the body becomes a part of the circuit. Electric shock normally occurs in one of three ways - when an individual is in contact with the ground and contacts: Both wires of an electric circuit, or One wire of an energized circuit and the ground, or A metallic part that has become energized by contact with an energized conductor. The metal parts of electric tools and machines may become energized if there is a break in the insulation of the tool or machine wiring. A worker using these tools and machines is made less vulnerable to electric shock when there is a low-resistance path from the metallic case of the tool or machine to the ground. This is done through the use of an equipment grounding conductor—a low-resistance wire that causes the unwanted current to pass directly to the ground, thereby greatly reducing the amount of current passing through the body of the person in contact with the tool or machine.

Electrical Burns Most common shock-related, nonfatal injury Occurs when you touch electrical wiring or equipment that is improperly grounded Very serious injury that needs immediate attention Typically occurs on the hands

Falls Electric shock can also cause indirect or secondary injuries Workers in elevated locations who experience a shock can fall, resulting in serious injury or death

Working on Energized Equipment (PPE)
Persons working on energized equipment must be familiar with the proper use of special precautionary techniques, PPE, insulating and shielding materials, and insulated tools

Working on Energized Equipment (PPE) cont.
Isolate the area from all traffic Post signs and barricades Use an attendant if necessary Use insulated tools, mats and sheeting Use electrical rubber sheeting to cover nearby exposed circuits

Don’t work on energized electrical parts: Without adequate illumination If there is an obstruction that prevents seeing your work area If you must reach blindly into areas which may contain energized parts You must be able to see what you are doing when working on energized equipment.

Must use electrical protective equipment that is appropriate for the work to be performed Proper foot protection (electrical rated) Rubber insulating gloves, hoods, sleeves, matting, and blankets Hard hat (insulated non-conductive) Persons working in areas where there are potential electrical hazards.

Use, store, and maintain your electrical PPE in a safe and reliable condition Wear non-conductive head protection Wear protective equipment Head protection - wherever there is a danger of head injury from electric shock or burns due to contact with exposed energized parts. PPE - for the eyes or face wherever there is danger of injury to the eyes or face from electric arcs or flashes or from flying objects resulting from electrical explosion.

Working on Energized Equipment (Tools) cont.
Hand-Held Electric Tools Pose a potential danger because they make continuous good contact with the hand To protect you, tools must: Have a three-wire cord with ground and be plugged into a grounded receptacle, or Be double insulated, or Be powered by a low-voltage isolation transformer 29 CFR (f)(5)(v)(C)(3)

Inspect tools before use Use double insulated tools Double Insulated Marking

Tools & Equipment Ground power supply systems, electrical circuits, and electrical equipment Frequently inspect electrical systems to insure path to ground is continuous Don’t remove ground prongs Ground exposed metal parts of equipment Two kinds of grounds are required by the standard: 1. Service or system ground. In this instance, one wire, called the neutral conductor or grounded conductor, is grounded. In an ordinary low-voltage circuit, the white (or gray) wire is grounded at the generator or transformer and again at the service entrance of the building. This type of ground is primarily designed to protect machines, tools, and insulation against damage. 2. For enhanced worker protection, an additional ground, called the equipment ground, must be furnished by providing another path from the tool or machine through which the current can flow to the ground. This additional ground safeguards the electric equipment operator if a malfunction causes the metal frame of the tool to become energized.

Working on Energized Equipment cont.
Electrical Protective Devices These devices shut off electricity flow in the event of an overload or ground-fault in the circuit Include fuses, circuit breakers, and ground-fault circuit-interrupters (GFCIs) Fuses and circuit breakers are over-current devices When there is too much current: Fuses melt Circuit breakers trip open

Ground-Fault Circuit Interrupter (GFCI) Detects a difference in current between the black and white circuit wires If a ground fault is detected, the GFCI can shut off electricity flow in as little as 1/30 of a second Difference in current - This could happen when electrical equipment is not working correctly, causing current leakage known as a ground fault.

Safe Work Practices Never use plugs or receptacles that can alter polarity Properly plug all connecting plug-ins Stay away from all unguarded conductors Never overload a circuit or conductor

Safe Work Practices cont. Know where the hazards are Properly maintain equipment No exposed parts or energized surfaces Use barriers and devices where appropriate No conductors to walk on or trip on No jewelry, or other metal objects around electricity

Test instruments, equipment and test leads must be visually inspected for external defects and damage before the equipment is used Test instruments and equipment and accessories must be: Rated for the circuits and equipment to which they will be connected Designed for the environment in which they will be used To include cables, power cords, probes, and connectors

Identify common hazards
On average, a worker is electrocuted every day Electricity causes 12% of workplace deaths Takes very little electricity to cause harm Significant risk of causing fires

Effects on the Human Body 1 mA (Can be felt by the body) 2-10 mA (Minor shock, might result in a fall) 10-25 mA (Loss of muscle control) 25-75 mA (Painful, may lead to collapse or death) mA (Last for 1 second, almost always fatal)

Clues that Electrical Hazards Exist Tripped circuit breakers or blown fuses Warm tools, wires, cords, connections, or junction boxes Worn or frayed insulation around wire or connection

Controlling Electrical Hazards Most electrical mishaps are caused by a combination of three factors: Unsafe work practices Unsafe equipment and/or installation, Workplaces made unsafe by the environment Electrical shocks, fires, or falls result from these hazards: Exposed electrical parts Overhead power lines Inadequate wiring Defective insulation Improper grounding Overloaded circuits Wet conditions Damaged tools and equipment Improper PPE

Wire Gauge WIRE Inadequate Wiring Hazards A hazard exists when a conductor is too small to safely carry the current Example: using a portable tool with an extension cord that has a wire too small for the tool. The tool will draw more current than the cord can handle, causing overheating and a possible fire without tripping the circuit breaker. The circuit breaker could be the right size for the circuit but not for the smaller-wire extension cord. Wire gauge measures wires ranging in size from number 36 to 0 American wire gauge (AWG)

Control – Use the Correct Wire Wire used depends on operation, building materials, electrical load, and environmental factors Use fixed cords rather than flexible cords Use the correct extension cord 29 CFR (a)(2)(ii)(J): The OSHA standard requires flexible cords to be rated for hard or extra-hard usage. These ratings are to be indelibly marked approximately every foot of the cord. Since deterioration occurs more rapidly in cords which are not rugged enough for construction conditions, the National Electric Code and OSHA have specified the types of cords to use in a construction environment. This rule designates the types of cords that must be used for various applications including portable tools, appliances, temporary and portable lights. The cords are designated HARD and EXTRA HARD SERVICE. Examples of HARD SERVICE designation types include S, ST, SO, STO, SJ, SJO, SJT, & SJTO. Extension cords must be durably marked as per (g)(2)(ii) with one of the HARD or EXTRA HARD SERVICE designation letters, size and number of conductors. Must be 3-wire type and designed for hard or extra-hard use

Overload Hazards If too many devices are plugged into a circuit, the current will heat the wires to a very high temperature If the wire insulation melts, arcing may occur and cause a fire, even inside a wall

Grounding Hazards Metal parts of an electrical wiring system that we touch should be at zero volts relative to ground Housings of motors, appliances or tools that are plugged into improperly grounded circuits may become energized If you come into contact with an improperly grounded electrical device, YOU WILL BE SHOCKED (switch plates, ceiling light fixtures, conduit, etc.)

Grounding Grounding creates a low-resistance path from a tool to the earth to disperse unwanted current When a short occurs, energy flows to the ground, protecting you from electrical shock, injury and death Grounding is a secondary method of preventing electrical shock. Grounded electrical systems are usually connected to a grounding rod that is placed 6-8 feet deep into the earth. Grounded - connected to earth or to some conducting body that serves in place of the earth. Grounded, effectively (Over 600 volts, nominal.) Permanently connected to earth through a ground connection of sufficiently low impedance and having sufficient ampere rating that ground fault current which may occur cannot build up to voltages dangerous to personnel. Grounded conductor. A system or circuit conductor that is intentionally grounded. Grounding conductor. A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.

GROUNDING !!!!

Improper Grounding Tools plugged into improperly grounded circuits may become energized Broken wire or plug on extension cord Some of the most frequently violated OSHA standards Extension cords may not provide a continuous path to ground because of a broken ground wire or plug. Electrical systems are often grounded to metal water pipes that serve as a continuous path to ground. If plumbing is used as a path to ground for fault current, all pipes must be made of conductive material (a type of metal). Many electrocutions and fires occur because (during renovation or repair) parts of metal plumbing are replaced with plastic pipe, which does not conduct electricity.

Bonding When filling metal containers use bonding wire and keep containers closed until after bonding Attach the bonding cable to a shiny metal Talk about gas station fires and static electricity.

Overhead Powerline Hazards Most people don’t realize that overhead powerlines are usually not insulated Powerline workers need special training and personal protective equipment (PPE) to work safely Beware of powerlines when you work in the vicinity with ladders, erecting antennas, moving equipment, etc. PPE may consist of rubber insulating gloves, hoods, sleeves, matting, blankets, line hose, and industrial protective helmets.

Insulation Check insulation prior to using tools and equipment Remove from service any tools or equipment with damaged insulation

Guarding of Live Parts Must guard live parts of electric equipment operating at 50 volts or more against accidental contact Use Approved cabinets/enclosures Location or permanent partitions making them accessible only to qualified persons Elevation of 8 ft. or more above the floor or working surface Mark entrances to guarded locations with conspicuous warning signs

Guarding of Live Parts cont. Must enclose or guard electric equipment in locations where it would be exposed to physical damage Note: Physical damage to conduit in picture. 29 CFR (g)(2)(ii)

Cabinets, Boxes, and Fittings Junction boxes, pull boxes and fittings must have approved covers Unused openings in cabinets, boxes and fittings must be closed Note: missing knockouts

Warn Others Use barricades to prevent or limit access to work areas If signs and barricades do not provide sufficient warning and protection from electrical hazards, an attendant shall be stationed to warn and protect employees Use safety signs, safety symbols, or accident prevention tags to warn others about electrical hazards

Visually Inspect Portable cord and plug connected equipment and flexible cord sets (extension cords) shall be visually inspected before use on any shift for external defects If there is a defect or evidence of damage to any electrical tools or equipment Immediately notify your supervisor Remove the item from service Tell your co-workers Possible external defects: Loose parts Deformed or missing pins Damage to outer jacket or insulation Evidence of possible internal damage

Conductive Work Locations Portable electric equipment & flexible cords used in highly conductive (wet) work locations, where workers are likely to contact water or conductive liquids, must be rated for the wet environment

Use of Flexible Cords More vulnerable than fixed wiring Flexible cords can be damaged by: Aging Door or window edges Staples or fastenings Abrasion from adjacent materials Improper use of flexible cords can cause shocks, burns or fire 29 CFR (g)

Working Safe with Cords Cords should be kept clean and free of kinks and insulation breaks Cords crossing vehicular or personnel passageways should be protected Cords should be of continuous length and without splices

Working Safe with Cords cont. Two or more extension cords plugged together are illegal Prevent strain on plug or receptacle

Permissible Uses of Flexible Cords Examples
Other examples: Elevator cables Wiring of cranes and hoists Prevention of the transmission of noise or vibration Appliances where the fastening means and mechanical connections are designed to permit removal for maintenance and repair Data processing cables approved as part of the data processing system Pendant, or Fixture Wiring Portable lamps, tools or appliances Stationary equipment-to facilitate interchange (g)(1)(i)

Prohibited Uses of Flexible Cords Examples
Substitute for fixed wiring Run through walls, ceilings, floors, doors, or windows Concealed behind or attached to building surfaces (g)(1)(iii)

What’s the hazard?

Temporary Lights Protect from contact and damage, do not suspend by the cord unless designed to operate that way

Panel Boxes Used to house circuit breakers that block or isolate energy Ensure panel boxes remain clear Label all circuits for what they control Label panel boxes for what they control Replace circuit breakers with blanks when not in use Note: Maintain 3 feet of unimpeded working space in front of electrical equipment.

Submit Work Requests Per installation’s regulations concerning facility maintenance work request submission system Ensure priority is identified Ensure follow-ups are conducted routinely Each school can add information on their particular location’s FacMaint. You can also show example of a work request form.

Documentation of hazards
In accordance with applicable references Utilization of Hazard Abatement Log Should be maintained by safety officer Upon completion of facility inspection, conduct after-action brief with appropriate command personnel Provide students with notice that you will review documentation of hazards further in the Inspection lesson. Supervisor should be notified immediately of hazards.

References NAVMC DIR 5100.8 Chapter 12 (LOTO) 29 CFR 1910 Subpart S
NFPA 70 National Electrical Code

Treat electricity with efficiently and effectively
Final Advice Treat electricity with the respect it demands, and it will serve you efficiently and effectively

Electrical Safety Program

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