Presentation on theme: "OSHA Region 1 Cooperative and State Programs Electrical Training/Inspection “Roll Up” Extension Cords GFCIs Power tools."— Presentation transcript:
1 OSHA Region 1 Cooperative and State Programs Electrical Training/Inspection “Roll Up” Extension Cords GFCIs Power tools
2 Electrical Training/Inspection Electrical equipment, cords and power tools are used in all industry settingsImproper use can result in serious injury or deathEstimated 4,000 injuries associated with extension cords (CPSC)In most casesGFCIs were not usedUngrounded cords were usedImproperly repaired or modified cords used
3 Use the Correct WireWire used depends on operation, building materials, electrical load, and environmental factorsUse the correct extension cord(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
4 Clues that Electrical Hazards Exist Tripped circuit breakers or blown fusesWarm tools, wires, cords, connections, or junction boxesGFCI that shuts off a circuitWorn or frayed insulation around wire or connectionThere are “clues” that electrical hazards exist. For example, if a GFCI keeps tripping while you are using a power tool, there is a problem. Don’t keep resetting the GFCI and continue to work. You must evaluate the “clue” and decide what action should be taken to control the hazard.There are a number of other conditions that indicate a hazard.Tripped circuit breakers and blown fuses show that too much current is flowing in a circuit. This could be due to several factors, such as malfunctioning equipment or a short between conductors. You need to determine the cause in order to control the hazard.An electrical tool, appliance, wire, or connection that feels warm may indicate too much current in the circuit or equipment. You need to evaluate the situation and determine your risk.An extension cord that feels warm may indicate too much current for the wire size of the cord. You must decide when action needs to be taken.A cable, fuse box, or junction box that feels warm may indicate too much current in the circuits.A burning odor may indicate overheated insulation.Worn, frayed, or damaged insulation around any wire or other conductor is an electrical hazard because the conductors could be exposed. Contact with an exposed wire could cause a shock. Damaged insulation could cause a short, leading to arcing or a fire. Inspect all insulation for scrapes and breaks. You need to evaluate the seriousness of any damage you find and decide how to deal with the hazard.A GFCI that trips indicates there is current leakage from the circuit First, you must decide the probable cause of the leakage by recognizing any contributing hazards. Then, you must decide what action needs to be taken.
5 Defective Cords & Wires Plastic or rubber covering is missing from capsOpen wiring used as extension cordDamaged extension cords & toolsExtension cords may have damaged insulation. Sometimes the insulation inside an electrical tool or appliance is damaged. When insulation is damaged, exposed metal parts may become energized if a live wire inside touches them. Electric hand tools that are old, damaged, or misused may have damaged insulation inside. If you touch damaged power tools or other equipment, you will receive a shock. You are more likely to receive a shock if the tool is not grounded or double-insulated.
6 Damaged Cords Cords can be damaged by: Aging Door or window edges Staples or fasteningsAbrasion from adjacent materialsActivity in the areaImproper use can cause shocks, burns or fireReference (a)(2)(ii)(I)The normal wear and tear on extension and flexible cords at your site can loosen or expose wires, creating hazardous conditions. Cords that are not 3-wire type, not designed for hard-usage, or that have been modified, increase your risk of contacting electrical current.
7 Improper GroundingTools plugged into improperly grounded circuits may become energizedBroken wire or plug on extension cordSome of the most frequently violated OSHA standardsThe most frequently violated OSHA electrical regulation is improper grounding of equipment and circuitry. The metal parts of an electrical wiring system that we touch (switch plates, ceiling light fixtures, conduit, etc.) should be grounded and at 0 volts. If the system is not grounded properly, these parts may become energized. Metal parts of motors, appliances, or electronics that are plugged into improperly grounded circuits may be energized. When a circuit is not grounded properly, a hazard exists because unwanted voltage cannot be safely eliminated. If there is no safe path to ground for fault currents, exposed metal parts in damaged appliances can become energized.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.
8 Wiring methods, components, and equipment for general use. Flexible cords protected from damageAvoid sharp cornersExtension cords 3-wire typeRated Hard or extra-hard dutyExtension cord sets used with portable electric tools and appliances shall be of three-wire type and shall be designed for hard or extra-hard usage. Flexible cords used with temporary and portable lights shall be designed for hard or extra-hard usage.
9 Wiring methods, components, and equipment for general use. Most flat type extension cords are molded and not rated for hard or extra-hard use and can not be used at work.Even if it has a UL label - this flat, molded and ungrounded cord can not be used at work.
10 Flexible cordsFlexible cords shall be connected to devices and fittings so that strain relief is provided.(Caps may be replaced if damaged)Even though proper ratings of the cord and caps are used flexible cords can not be spliced in this manner.
11 Wiring Design and Protection All conductors singularly identifiableNo reversing polarity on conductorsReversed polarity is a condition when the grounded conductor (neutral) is incorrectly connected to the ungrounded (hot) terminal of a plug, receptacle, or other type of conductor.Identification of conductors. A conductor used as a grounded conductor shall be identifiable and distinguishable from all other conductors. A conductor used as an equipment grounding conductor shall be identifiable and distinguishable from all other conductors.Polarity of connections. No grounded conductor shall be attached to any terminal or lead so as to reverse designated polarity.
12 Environmental deterioration of equipment. Unless listed or identified for use no conductors or equipment located in:Damp or wet locationsHarmful chemicals, fumes or vaporsExcessive temperatures
13 Listed, labeled or certified equipment shall be installed and used in accordance with their instructions.Knockout type boxes are not listed/labeled to be used as extension cords or pendants.Multi tap outlets need to be approved for their use. This one can not be used on construction sites.
14 Extension cords can be abused Damage to insulation and conductors can occur if the cord is improperly wound.
15 Ground fault circuit interrupters (GFCI’s) A GFCI is not an overcurrent device like a fuse or circuit breaker.GFCI’s are designed to sense an imbalance in current flow over the normal path.
16 Ground fault circuit interrupters (GFCI’s) GFCI contains a special sensor that monitors the strength of the magnetic field around each wire in the circuit when current is flowing.The field is proportional to the amount of current flow.
17 Ground fault circuit interrupters (GFCI’s) If the current flowing in the black (ungrounded) wire is within 5 milliampers of the current flowing in the white (grounded) all the current will flow in the normal path.If the current flow differs by more than 5mA, the GFCI will quickly open the circuit.
19 Types of GFCI’s Circuit Breaker type: Includes the functions of a standard circuit breaker with the additional function of a GFCI.Installed in a panelboard and can protect an entire branch circuit with multiple outlets.A direct replacement for a standard circuit breaker of the same rating.
20 Types of GFCI’s Receptacle type: Incorporates within one device one or more receptacle outlets, protected by the GFCI.Popular and inexpensive.Most are of duplex typeCan protect additional non-GFCI type receptacles connected “downstream”.
21 Types of GFCI’s Permanently Mounted type: Mounted in an enclosure and designed to be permanently wired to the supply.Frequently used around commercial swimming pools or similar wet locations.
22 Types of GFCI’s Portable type: Some plug directly into non-GFCI outlets.Incorporate no-voltage release device which will disconnect power to the outlets if any supply conductor is open.Units for outdoor use will be in suitable enclosure.Will be listed if for rain use.
23 Types of GFCI’s Cord Connected type: Attachment plug incorporates the GFCI module.Protects the cord, and any equipment attached to the cord.Attachment has non-standard appearanceEquipped with test and reset buttons.No-voltage release feature
24 Testing GFCI’sGFCI’s are complex mechanisms, they must be tested on a regular basis.For permanently mounted types, once a month testing is recommended.Portable GFCI’s should be tested before each use.GFCI’s have a test-circuit which imposes an artificial ground fault when the test button is pushed.
25 Testing GFCI’s Push test button and make sure the GFCI trips. (A click will be heard )Push reset button and make sure the GFCI is activated.A click will be heard
26 Power Tools - Precautions Disconnect tools when not in use, before servicing and cleaning, and when changing accessoriesKeep people not involved with the work away from the workSecure work with clamps or a vise, freeing both hands to operate the toolDon’t hold the switch button while carrying a plugged-in toolRemove damaged electric tools & tag them: “Do Not Use”
27 Power Tools - Precautions Consider what you wear – loose clothing and jewelry can get caught in moving partsKeep tools sharp and cleanUse PPE, such as safety glasses, goggles, face shield, gloves, hearing protection, respirator, hard hat
28 Power Tools – Precautions Electric Cords Don’t carry portable tools by the cordDon’t use electric cords to hoist or lower toolsDon’t yank cord or hose to disconnect itKeep cords and hoses away from heat, oil, and sharp edges(a)(2)
29 Electric Power Tools To protect a worker from shock, these tools must: have a 3-wire cord plugged into a grounded receptaclebe double insulated, orbe powered by a low-voltage isolation transformerDouble insulated markings(a)(1)Three-wire cords contain two current-carrying conductors and a grounding conductor. Any time an adapter is used to accommodate a two-hole receptacle, the adapter wire must be attached to a known ground. The third prong must never be removed from the plug.Double-insulated tools are available that provide protection against electrical shock without third-wire grounding. On double-insulated tools, an internal layer of protective insulation completely isolates the external housing of the tool.Plug with a grounding pin
30 GroundingGrounding creates a low-resistance path from a tool to the earth to disperse unwanted current.When a short or lightning 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 ampacity 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.
31 Ground Tools & Equipment Ground power supply systems, electrical circuits, and electrical equipmentFrequently inspect electrical systems to ensure path to ground is continuousInspect electrical equipment before useDon’t remove ground prongs from toolsor extension cordsGround exposed metal parts ofequipmentA typical extension cord grounding system has four components:a third wire in the cord, called a ground wire;a three-prong plug with a grounding prong on one end of the cord;a three-wire, grounding-type receptacle at the other end of the cord; anda properly grounded outlet.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.
32 Tool Safety Tips Don’t carry a tool by the cord Don’t yank the cord to disconnect itKeep cords away from heat, oil, &sharp edgesDisconnect when not in use and when changingaccessories such as blades & bitsRemove damaged tools from useAvoid accidental starting. Don’t hold fingers on switch button while carrying a plugged-in tool.Tag damaged tools: "Do Not Use."Hazards of portable electric tools:- Currents as small as 10 mA can paralyze, or “freeze” muscles: person cannot release tool.- Tools are held tightly, resulting in longer shock exposure.- Power drills use 30 times as much current as what will kill.
33 SummaryHazards are usually the result of improper tool use or not following one or more of these protection techniques:Inspecting the tool before useloose clothing and jewelry can get caught in moving partsUse PPE, such as safety glasses, goggles and glovesUsing guardsProperly storing the toolUsing safe handling techniques