Presentation on theme: "Electrical Safety Safety Training Series"— Presentation transcript:
1 Electrical Safety Safety Training Series The Business 21 PublishingSafety Training SeriesTake Personal Responsibility for Safety and Make a DifferenceA user-friendly training module to help supervisors and workers:Understand the causes and consequences of electrical injuries at work.Prevent these injuries.Supervisors: This presentation contains 40 slides.If you have, say, an hour to give it, you’ll need to change slides every 90 seconds or so in order to get through the presentation and have time for questions and/or demonstrations.The slides contain 12 Real-Life Stories of injuries due to lapses in electrical safety. If you want to tell them, you’ll have to move more rapidly through some of the other slides.NOTE TO TRAINER: As instructors, we can have a tremendous impact on workers’ attitudes and behaviors about safety. We can:help workers develop an understanding of the language used in safetyredefine our organization’s safety culture by the way we teach safetyinfluence workers to take personal responsibility for safety, andmotivate workers to always set the right example – to walk the safety talk.Business 21’s Safety Training Series strives to inspire everyone to take safety personally and act accordingly.
2 About this presentation By the end of this presentation, you’ll be able to:Spot potentially dangerous situations involving work with and around electricity.Avoid these situations, or find safe ways of handling them.Employees respond better when they understand not only what they’re supposed to do, but also when, how, and especially why. Throughout the supervisor’s notes accompanying this presentation, we’ll provide you with anecdotes taken from real experience to help answer those questions.Feel free to pause the presentation at any time to go into these real-life stories and reinforce your point.Important note: Take time to know your audience. Have class members share their names and give a personal story about safety.Also, ask what helps them listen and become involved with a safety training program. Some of the best lessons we instructors learn come when we listen to our students.
3 Electrical injuries and fatalities at work … Between 300 and 400 deaths per year.More than 5,000 injuries requiring time off work per year.Between 5% and 6% of all work-related fatalities are from electrical shocks and/or burns.Electrical injuries can and do take place in any occupation – from manufacturing worker to miner to secretary in a white-collar office.Construction workers are the most vulnerable to electrical injury. This isn’t surprising – they work in cluttered settings where electrical fittings are often being installed, and many of the tools they use are electrically powered. Plus, the electric power supply for construction sites is usually temporary in nature, and subject to more safety hazards than fixed wiring usually is.Construction workers account for 7% of the U.S. workforce, but they sustain 45% of all work-related electrical fatalities. However, as you’ll see in the examples that follow, manufacturing and other facilities are full of potentially deadly electrical hazards, too.
4 Who can help prevent unsafe electrical set-ups? Who is the competent person (or persons) for electrical processes at your site?Everyone must know who this person is.The first line of defense against the electrical injuries and fatalities we’ve been discussing is the “competent person” for the electrical process in your work environment.“Competent person” is an OSHA term [regulation (f)] and it means someone who is capable of identifying existing and predictable hazards in the surroundings or working conditions. This person has authorization to take prompt corrective measures to eliminate these dangers.Important: All workers should be aware of who the competent person for electrical processes is. This individual can provide the information to protect each worker.Supervisors should remember that if OSHA needs to visit a site, the inspector will ask to speak to the competent person for each trade.
5 How serious are electrical injuries at work? They tend to result in long periods of disability.They can cause deep, long-lasting harm that is very expensive to treat and/or correct.They affect a company’s safety culture and the insurance process.Everybody knows the saying, “Familiarity breeds contempt.” With electricity, it’s more like “Familiarity breeds carelessness.”Since electrical power was tamed by such people as Edison and Tesla a century ago, electricity has become omnipresent in the industrial world. We think nothing of flipping on a light switch or plugging in a vacuum cleaner, power drill or table saw.In all of this, we tend to forget the awesome power of the energy giant we’ve harnessed, and how deadly it can be if it escapes the harness. In the workplace, that forgetfulness can easily result in horrific injuries and burns when proper precautions aren’t taken to channel the electricity colossus.Electrical injuries can be devastating to skin, flesh, tendons, bones and internal organs. The consequences of these injuries show up in a couple of striking statistics:Of electrical injuries caused by contact with overhead power lines, up to 60% of cases result in more than a month out of work. That compares with around 20% for all occupational injuries and illnesses.Severe electrical injuries cost up to $15 million per case, in direct and indirect costs! Yes, you read that number right. This total includes medical care – for severe electrical injuries, many rounds of surgery and months or years of care as well as increased workers’ compensation costs, worker replacement costs, and other expenses.
6 What are the main types of electricity-related injuries? ShocksBurnsFallsElectric shock is, of course, the primary injury that workers sustain as a result of lapses in electrical safety. But you can hurt yourself in other ways, too.Electrical burns often accompany electric shock. These can either be superficial – the skin is burned off, sometimes over a wide area – or involve deep tissue, penetrating into the muscles so far that entire limbs can be charred.Falls are another common type of electricity-linked injury. Workers standing on ladders may fall off if they are shocked, or may be knocked off their feet by an electrical discharge. Broken bones and brain injuries are all-too-frequent consequences of falls caused by electric shock, sometimes when the shock wasn’t strong enough to cause serious injury by itself.
8 What creates an electric shock? Touching wires with different voltages.Touching a live wire and an electrical ground.A worker – or anybody else – can be shocked and injured or killed if his or her body completes an electrical circuit. There are three main ways that you can inadvertently do this:Simultaneously contacting wires that have different levels of electrical force, as measured by volts. If you’re dealing with alternating rather than direct current, even two wires carrying the same voltage level – say, 240 volts – can shock you. That’s because one may be carrying -120 volts while the other carries +120 volts, due to the cycling of the alternating current.Contacting a conducting wire when you are grounded. This can happen if you are, say, working inside an energized circuit box and touch both the energized wire and the neutral, or ground, wire. Or you could be grounded by touching a metal electrical box or conduit. As most people know, you ground more easily if you’re standing in water. But you are also at increased risk of becoming the ground connection in the circuit if you’re sweating, or even working in high humidity.Touching another person who is being shocked can ground and shock you, too.Note: At this time it would be a good idea to have an electrician talk about these and other situations that can cause electric shock. An experienced member of the class might do, or you can invite someone in.
9 What are the factors of injury from electric shock? Amount of current measured in milliamperes.NOTE: As little as 50 milliamps is enough to kill you … a simple hair dryer draws 10,000 milliamps.Don’t be fooled into thinking you can be electrocuted only at high voltages, like the hundreds of volts in industrial circuits or the thousands in high-tension power lines.People have suffered respiratory arrest from electric shock at under 50 volts. An ordinary household circuit, by comparison, is rated at 110 volts.What counts most in determining how badly you’ll be shocked is the amperage, or amount of current, which generally goes up with the voltage. Note that even common household amperages – not to mention those associated with heavy-duty industrial equipment – may be enough to kill you. A household fuse or circuit breaker usually won’t trip at less than 15 amps, which is more than 300 times the current necessary to kill under some circumstances. Another comparison: A hair dryer draws about 10 amps of current, again much more than needed to kill you. (Which is why you don’t use one in the bathtub.)A shock at less than 5 milliamps is unlikely to do more than make your hand tingle, or give you a jolt. But from 6 milliamps and up (for women) and 9 milliamps and up (for men), serious injury is possible. At this level, the person being shocked may not be able to let go of the contact, because he or she has lost muscular control.Death becomes a possibility from 50 milliamps and up. (Remember that hair dryer? Its 10 amps equal 10,000 milliamps.) At that level of current, breathing may stop, and contraction of a person’s muscles may cause him or her to be thrown violently away from the point of contact. At 1,000 milliamps, your heart goes haywire, and at 10,000 milliamps it stops.
10 Factors that cause electric shock injury (continued) Length of time the current passes through the body.Path of the current through the body.The longer the shocking contact lasts, the worse its effects. A shock that wouldn’t hurt you badly may kill you if you’re “frozen” to the contact point.The other factor of injury is the path the current takes through your body. The most injurious paths involve the head and chest. So for instance, if you contact a live wire with one hand while you’re grounded through your opposite arm, the current will likely flash past and/or through your heart and lungs.
11 What about electrical burns? 38% of electrical injuries involve burns, which can range up to third-degree.Electrical burns take three main forms:Contact burnsArc burnsThermal burnsMost electrical fatalities are from shocks rather than burns, but burns can be extensive, painful and slow to heal. Electrical burns are of three main kinds:Contact burns result from touching electrical wiring or equipment that hasn’t been properly maintained.Arc burns result from the intense heat and light generated by “arcing” – the jumping of high-voltage electricity through the air between conductors. Arc blasts have been measured at up to 35,000 degrees Fahrenheit! Arc blasts can also produce a pressure wave strong enough to throw a victim backward, damage his or her hearing and cause concussion.Thermal burns result when an electrical discharge ignites combustible vapors or dust in the air, or when a worker’s clothing catches fire.Let’s look at a case where a worker received arc burns, and became totally disabled.REAL-LIFE EXAMPLEGreg worked for a company that set up and serviced mobile homes. One day he was working on the chimney of a mobile home when electricity arced unexpectedly from a nearby power line to his face.Greg sustained awful facial burns that required a long series of skin grafts. Beyond the disfiguring burns, he sustained a brain injury that left him unable to work for life. This was bad news for the employer, too, whose workers comp insurance had to pay out more than $250,000 in disability benefits.(ask the participants)What did Greg do wrong?Correct answer: At least two things: First, he should have made sure the power line near where he was working was de-energized before carrying out his task. Second, he should have made sure he wore personal grounding protection, such as rubberized soles and/or a hard hat rated for electrical work.(Barnes v. K.C. Flooring, South Carolina Workers’ Compensation Commission)
12 FallsWhen working around electricity and at heights (ladder, scaffold, etc.):Take precautions to avoid being shocked, but,Plan for a fall as if you expected to be shocked.As we mentioned earlier, even a trivial electrical accident can become grave or fatal if the shock causes you to fall from a height.Ways to avoid or mitigate electrically induced falls include:Using the right type of ladder or properly grounded scaffolding. Wooden ladders are acceptable, but fiberglass is better. If wood stands in a wet area for an extended period, it can become permeated with moisture and turn into a conductor.Wearing the right protective clothing, including hard hat, gloves, rubberized shoes, etc. We’ll discuss the kind of hard hat you should have for electrical work later on.Tying yourself off according to the usual standards for working above-ground – 10 feet or more.REAL-LIFE EXAMPLEDante, a shop mechanic, was running electrical lines for a bank of fluorescent lights in a ceiling at work. He was using an eight-foot ladder to access the ceiling.For some reason, Dante received a strong electric shock and fell six feet to the bare concrete floor. Five years later he still wasn’t able to resume work, due to nerve damage in his arm and spine from the shock, as well as disk damage in his lower back from the fall.(ask the participants)What did Dante do wrong?Correct answer: He should have made sure the offending circuit was de-energized before working on or around it. Also, knowing that he was working around electricity and that he might get shocked, he could have placed a protective cushion – like an old mattress – on the floor near his ladder. That wouldn’t have saved him from the electric shock, but it would have prevented the worst of his back injuries.(Brown v. Pepco, District of Columbia, Office of Employment Services, Hearings & Adjudication Section)
13 Common types of electrical accidents? Direct or indirect contact with an overhead electric power line.Installation/maintenance of electrical equipment.Incidental contact with energized circuits.Installation/maintenance of power transmission or distribution lines.Almost every employee is vulnerable to at least one of these four common types of electrical accident.True, only a minority of workers have the job of installing power transmission lines. And not everybody will work underneath an elevated power line at some point in their career.But lots of employees work on electrical equipment like lighting fixtures or HVAC equipment, and almost everyone risks coming into contact with an energized circuit – right down to the fast-food worker who tries to plug in a defective toaster or fryer.Note: A very important point to make here is – Never assume something is not “hot,” or electrically charged. All workers must check everything before they start working. No one should ever hesitate to ask the advice of the competent person or electrical contractor.
14 Electrical accidents: Type #1 Direct or indirect contact with an overhead power line.Everybody who works around overhead power lines, even temporarily, ought to be trained to respect these dangerous installations. For the most part, they’re NOT INSULATED!And yet over a recent six-year period, 39% of fatal electrical accidents at work involved contact with an overhead power line. This was either direct touching via a pole, ladder, piece of scaffolding, etc., or indirect contact via a vehicle like a crane, boom truck or drill rig.Here’s one such story.REAL-LIFE EXAMPLEMartin worked for a fencing company. He was part of a crew building a chain-link fence in front of a customer’s house. The house was directly beneath a 7,200-volt overhead power line.The sections of metal rail for the top of the fence were 21 feet long. Martin picked up one of these and held it vertical. The top of the rail touched the power line, and Martin was struck dead, electrocuted on the spot.What did Martin do wrong?Correct answer: He didn’t respect the required clearance from a power line. This is 10 feet for lines carrying up to 5,000 volts, or 50kV, and adds 4 inches for every 10kV upwards of 50kV. So Martin should have kept his rail at least 10 feet 8 inches from the power line.(From NIOSH Publication “Electrical Safety – Safety & Health for Electrical Trades,” company name withheld)
15 Electrical accidents: Type #2 Installation and maintenance of electrical equipment and/or systems.Over the six-year period we mentioned earlier, 22% of fatal electrical accidents involved employees who were installing or doing maintenance on electrical systems and equipment.In many cases, the employee(s) were working on or near live circuits or live wires that they were unaware of.Here’s one such story.REAL-LIFE EXAMPLEVirgil did maintenance work in a factory. One of the overhead lighting fixtures was malfunctioning, so Virgil was directed to fix it.Virgil moved a motorized lift into place, then rode it up 12 feet to get at the fixture. He didn’t disconnect the power to the fixture, because that would have turned off two other nearby lights and he felt he needed them to see. Besides, Virgil was an experienced electrician, and he knew which wires he could safely touch.Or did he? It turned out that somebody had improperly installed the circuitry. The black wire, which should have carried current, was in fact the neutral or ground wire. The white wire, which should have been the ground, was live. As Virgil stripped insulation from the white wire, 277 volts of power leaped from it into his right hand and then his body, exiting to ground through his left index finger.A co-worker noticed Virgil lying on the lift, lowered it and performed CPR. But it was too late. Virgil was dead.What did Virgil do wrong?Correct answer: He should have de-energized the circuit controlling the fixture, then locked and tagged it out so somebody wouldn’t turn it back on while he was working there. To illuminate his work, he should have had a portable lamp available.(From NIOSH Publication “Electrical Safety – Safety & Health for Electrical Trades,” company name withheld)
16 Electrical accidents: Type #3 Incidental contact with energized circuits.Some 19% of fatal accidents over the six-year period were caused by incidental contact with energized circuits.This kind of accident can happen to almost anybody, at work or elsewhere, because we live surrounded by energized circuits.Here’s an example, which wasn’t fatal but cost both the employee and employer dearly.REAL-LIFE EXAMPLE #1Gina was a bank teller. When the tellers would take turns at the drive-in window in the wintertime, it would get cold in their little booth, so they used space heaters to keep warm.One day as Gina prepared to start her duty at the drive-in window, she pulled a space heater out of the storage closet and took it over to her station. As she tried to plug it in, the cord came loose from the heater and she received a strong shock. When she came to herself, she was standing all the way at the back of the office, on the other side from the drive-in window, with no memory of how she got there.Gina suffered a horde of physical and psychological symptoms as a result of the incident, and was on workers’ compensation for two years, costing her employer thousands of dollars. Her sleep was ruined and she suffered what a psychologist described as post-traumatic stress disorder.What did Gina do wrong?Correct answer: Either Gina, or someone else at the bank, should have periodically checked the condition of the space heaters. If the cord came loose under the pressure of normal use, something was defective.(Stroope v. Farmers Bank & Trust, Arkansas Division of Workers’ Compensation)Virtually every workplace contains electric equipment that can shock the user. In the above example, the heater was used only periodically. But in the next example, equipment that the worker used every day shocked her.REAL-LIFE EXAMPLE #2Marcella worked as a security guard in a government building in Washington, DC. One of her daily duties was to operate the security scanner at the building entrance. One day as she was doing this job, touching a button to move the scanner’s conveyer belt, an electric spark jumped from the button to her right hand and current traveled up her arm into her shoulder. The current was strong enough that Marcella had to fight to pull her arm away.Marcella’s hand quickly started to swell and become darker. She was eventually diagnosed with damage to the ulnar nerve, in her elbow, and received six months worth of workers comp benefits. At the end of that time, she was still unable to work.What did Marcella do wrong?Correct answer: In this case, probably nothing. Maintenance of the scanner and other equipment was probably not her responsibility. But if she or any co-worker had noticed anything odd about the operation of the scanner prior to the accident, and not reported it, they should have.(Shamburger v. Unlimited Security, District of Columbia Office of Employment Services, Hearings & Adjudication Section)
17 Electrical accidents: Type #4 Installation/maintenance of power transmission or distribution lines.This is the kind of accident that can have the most tragic consequences because of the very high voltages that are often involved. These accidents often cause horrific burns, and they’re disproportionately fatal.Here’s a story of such a fatal accident.REAL-LIFE EXAMPLECarlos was part of a line crew that repaired high-tension power lines and towers. He was on a particularly challenging job, replacing insulation near the top of a tower more than 100 feet high. The tower carried two transmission lines, only one of which was de-energized during the work.Because the bucket truck the crew had brought along could reach to only 85 feet, the linemen had brought along an insulated ladder that Carlos attached to the top tier of the tower, so he could get to the highest insulators.Carlos was nearly finished with the job, and a co-worker was repositioning the bucket truck to pick him up, when something happened. The co-worker saw Carlos slump backward until he was hanging upside down, with his legs caught in the ladder.It took an hour-and-a-half to get Carlos down, partly because of a delay by the electric company in shutting off the circuit that had remained energized. Paramedics were not allowed to touch him until that had been done. Burned savagely on an arm and a leg, he died at the hospital shortly after arriving.What did the line crew do wrong?Correct answer: Apparently the circuit that was supposed to have been de-energized was re-energized at some point, for reasons that remained unclear afterward. Carlos and his co-worker couldn’t have done much about that, but the investigation into the accident showed something they could have done. Their personal grounding protective equipment was inadequate, and they should have insisted on proper equipment before Carlos climbed to his death.(Ruiz v. Herman Weissker Inc., California Court of Appeal)
18 Main on-the-job hazards linked to electricity? Inadequate wiring.Exposed electrical parts.Bad/defective insulation.Electrical systems that are not grounded.In the next two slides, we list the main electrical hazards you’re likely to encounter at work. Then in the following slides, we’ll go into individual analyses of each hazard.
19 Main on-the-job hazards (continued) Damaged power tools.Overloaded circuits.Overhead power lines.Wet conditions.These are the other four major electrical hazards at work, making eight in all.
20 Hazard #1: Inadequate wiring Watch for:Replacement fixtures that pull more current than the circuit’s wiring is rated for.Extension cords whose wiring is inadequate for the tool you’re using.You probably know that wiring of too light a gauge for the current it’s asked to bear can heat up and cause a fire.Normally, circuit breakers will kick in before wiring can overheat.But you can inadvertently defeat the breaker by plugging inadequate wiring into the existing circuit, for example, by using an extension cord whose wire gauge is too small for the electrical demand you’re putting on it.Another way that wiring can overheat happens when somebody has replaced, say, a lighting fixture with another more powerful one and not upgraded the wiring leading to it.
21 Hazard #2: Exposed electrical parts Why parts may be exposed:Someone has removed the cover from a wiring or breaker box.Older electrical equipment may have exposed parts due to design or damage.Terminals in motors and appliances may be exposed.Obviously, if you contact live electrical parts, you’re virtually certain to get a shock. You need to examine the work site for these exposed parts, and either cover them, or de-energize the equipment in which they’re found while you’re working.Again, take safety personally. What you neglect to do can have an impact on someone else.The worker in the following story didn’t check for exposed electrical parts, and paid the price.REAL-LIFE EXAMPLE Bill, who worked for an electrical contractor, was doing maintenance on hot water lines in the ceiling at a hospital.As he leaned back on his ladder to get a look at something directly overhead, the back of his neck contacted a live circuit carrying 277 volts.He was so powerfully electrocuted that he was “stuck” to the ceiling for several seconds even after co-workers kicked the ladder out from under him. Finally the circuit breaker tripped and he dropped to the floor, convulsing and with smoke coming out of his mouth.Bill missed six months of work and then started working again. But he found he couldn’t remember things, and he was scared stiff of electricity, so he eventually became unemployed.Bill’s employer was liable for more than $100,000 in permanent total disability payments to him.(ask the participants)What did Bill do wrong?Correct answer: Bill should have made sure the circuit behind him was either covered or de-energized. And he might have reduced the violence of the electrocution if he’d been using an insulated ladder.(Smith v. W.N. Kirkland Inc., South Carolina Workers’ Compensation Commission)
22 Hazard #3: Bad or defective insulation Situations to beware of:Extension cords with damaged insulation.Hand tools with damaged or old insulation inside them.Wires are insulated with a plastic or rubber coating that prevents people from coming in contact with live current, and also prevents conductive wires from touching each other.Insulation can crumble with age or exposure to harsh conditions, however. It can also be burned off. In the case of an extension cord, you can usually see the insulation damage, and such a cord should be thrown out immediately.Missing or damaged insulation inside a power tool may be harder to detect. The best way to guard against a shock in this case is to use tools that are grounded or double-insulated. Double-insulated tools have two insulation barriers and no exposed metal parts.Class project: If time allows it can be valuable to walk the site nearest you and inspect cords and tools. As you walk, compliment safe practices you find and correct situations that are unsafe. Everyone needs to understand that you can make a difference by not just walking by a safety hazard.
23 Hazard #4: Ungrounded electrical equipment This is the most common violation of OSHA regs on electrical safety. The main problems are:Metal parts of an electrical wiring system like switch plates and light fixtures if the system is not grounded properly.Metal parts of motors or appliances plugged into improperly grounded circuits.In all these cases, improper grounding can cause electricity to flow through you when you touch the system or component, instead of flowing through the ground wiring to the ground.Either poor installation or damage can cause these grounding hazards.The best way to guard against grounding deficiencies is the Ground Fault Circuit Interrupter, or GFCI, which we’ll discuss a little later.
24 Hazard #5: Damaged power tools Broken ground wires or plugs on extension cords or tools.This problem is a variant of Hazard #4, but we’ve listed it separately because in the case of extension cords or tools, you can do a lot to solve the problem.Regular inspection of extension cords or tools, especially those that are in constant use by a variety of people, is essential to avoid electric shocks due to grounding faults.Such tools should be either fixed or discarded, not left in use so that a hurried worker has only two bad choices:waste time looking for another tool, oruse the broken one, at his or her risk.
25 Hazard #6: Overloaded circuits Why they’re dangerous:They can overheat and cause fires.They can arc, producing dangerous, unpredictable flashes.A circuit gets overloaded when one of two things happens:Too many devices are plugged into it, orA single tool drawing a lot of current exceeds the rating of the circuit.When a circuit is overloaded, the wires can get hot enough to cause a fire.And if the temperature is really hot and the insulation melts, arcing can occur. Arcing is dangerous to workers when it’s in exposed places, but when it happens inside a wall, say, it’s potentially even more dangerous because the fire it creates may build undetected to catastrophic proportions.Circuits should have breakers, sure, and if they’re equipped with the right breaker, fire will be prevented. But sometimes breakers are too large for the circuits they’re guarding, and don’t trip soon enough to avoid fire. Or sometimes a circuit – especially one that’s been created for temporary purposes, as on a construction site – may not have breakers at all.Any circuit with no overload protection, or the wrong overload protection, is a dangerous hazard. Also, if the overload protection within a tool is damaged, the tool can catch fire.
26 Hazard #7: Overhead power lines Out of sight, out of mind: When the danger is overhead, workers may forget about it until it’s too late.We’ve already gone over the dangers of overhead power lines in slide #12. But because these dangers are so insidious, it’s worth repeating:Know the required clearance distances for the power lines you’re dealing with, and respect them. Workers carrying any object taller than themselves must pay particular attention not to lift these objects into contact with the power lines.In the following case, the worker didn’t pay enough attention and suffered the consequences.REAL-LIFE EXAMPLE Steve worked for a company that poured concrete at construction sites. On one job site, there was a power line 20 feet above the spot where Steve’s crew was pouring a foundation.As they poured, a rock fell from the side of the excavation onto the setting concrete. Steve went to his truck to get a metal pole to try to knock the rock off the recently poured surface. As he approached the excavation carrying the pole vertically, it contacted the overhead power line, shocking him.Steve survived, but he needed skin grafts to repair his left foot, where the electrical current exited his body. He also suffered from muscle spasms in his back and chronic headaches that his doctor said were results of his electrical injury. He wasn’t able to work for more than a year.(ask the participants)What did Steve do wrong?Correct answer: Steve probably shouldn’t have used a metal pole at all around an overhead power line. But if it had been absolutely necessary to use the pole, he should have kept it horizontal as he carried it.(Woodberry v. H&H Concrete Co., Arkansas Division of Workers’ Compensation)
27 Hazard #8: Wet conditions Any dangerous electrical situation gets worse when water or humidity is involved.Water is a very efficient conductor of electricity. So if you’re standing in a puddle, or lying on wet earth, when your power tool shorts out you can be very badly hurt indeed.Remember that you don’t have to be wringing wet to be at greater risk. If your shirt is damp with sweat, that can be enough to exacerbate an electric shock.And because your skin has less electrical resistance when it’s wet than when it’s dry, any electrical injury suffered to wet skin is likely to be more severe than it would be otherwise.Here’s a case where a lot of things went wrong, but the fatal effect was augmented by moisture.REAL-LIFE EXAMPLEMolly worked as a delivery and service person for a home appliance dealer. Part of her job was installing the appliances, meaning that she had to connect them to water and/or electrical lines as appropriate.On one job, Molly and her assistant were delivering and installing an ice maker. They had to cut off the main water line first before they could hook up the appliance.It turned out that the master valve was accessible only by crawling into the crawl space under the house, so that’s what Molly did. It was a humid day, and both Molly and her assistant were sweating from the exertion of lifting the ice maker.After Molly had been in the crawl space for 10 minutes, her assistant called her. She didn’t answer. The assistant called again. Still no answer. He crawled in after her, and found her lying dead, electrocuted by a tangle of wiring. The earth in the crawl space was damp, investigators found later, and the wiring was both abraded and not the right specification for damp conditions.(ask the participants)What did Molly do wrong?Correct answer: The damp earth should have alerted her to a possible electrical hazard. True, it’s impossible to know whether Molly would have survived had the earth not been wet, but the bad combination of unprotected wiring and moisture made survival all that much more unlikely.Also, it wouldn’t have been a bad idea to cut off the power before Molly went under the house.(Westbrooks v. Ronnie’s Appliances, North Carolina Industrial Commission)
28 Safety measures to prevent electrical injury Lock out and tag out circuits and machines.Use the right size and type of wire.Isolate live electrical parts and equipment.Use proper insulation.In the next two slides, we present eight precautions that will help prevent electrical injury in a variety of circumstances. Then we’ll analyze each precaution in more detail.
29 Preventive measures (continued) Ground electrical systems and tools.Use ground fault circuit interrupters (GFCIs).Use overload protection devices.Wear appropriate personal protective equipment.Make electrical safety personal.Here are the final four of eight precautions against electrical injury.
30 Preventive measure #1: Lockout/tagout all circuits and machines Lockout/tagout is a key safety procedure for all sources of industrial energy, including electricity.This may be the most important preventive measure of all. Lockout/tagout, when done properly, prevents circuits from becoming energized while people are working on or around them.Think about it: Many of the fatal and non-fatal injuries we’ve discussed so far would have been avoided if lockout/tagout had been in place.Here are the main steps of lockout/tagout for electrical equipment or circuits:Identify all sources of electrical energy and shut-offs for each source.Disable backup sources like generators and batteries.Shut off energy sources and lock the switchgear in the Off position. It’s not enough to turn a switch off – each switch must be locked Off. Each employee working on the project should use his or her individual lock. Keys should not be shared.Test equipment to make sure it is de-energized.Drain any stored energy by grounding the equipment or circuit.Put on a tag to notify others that the equipment or circuit has been locked out.Do the maintenance or repair.Make sure all hands are safe and accounted for before equipment and circuits are unlocked and turned back on.
31 Preventive measure #2: Choose the right size and type of wiring If you’re working on a project where it’s possible to install a fixed wiring system, do so. Fixed wiring is more safe and reliable than extension cords.If you must use extension cords, use the right size wire and make sure connectors are in good condition.Extension cords are useful and flexible, but they have their limits. You should never use them if they:Run through holes in walls, ceilings or floors.Run through doorways or windows, unless the cord is physically protected so the wire won’t be crimped or otherwise damaged if the door or window is shut.Are attached to a building surface, unless there is a tension take-up device within six feet of the end of the cord nearest the electrical supply.Are hidden in walls, ceilings, floors or conduits.Choosing the extension cord with the right size wire is critically important, too. As we’ve said earlier, the wrong size wire can start a fire.Calculate the total current (in amps) that will be needed to power all the devices that will feed off the cord. Then choose the right wire size. For example, a #10 AWG (American Wire Gauge) cord will handle up to 30 amps.If the extension cord is long, you may have to beef up the size of the wire, because voltage drops over the length of a cord, and operating at low voltage can damage some equipment.And don’t forget grounding. Extension cords for industrial use have three wires, one of which is the ground wire. The three-pronged plug at the end of the cord, as well as the three-hole receptacle at the other end, must be in good condition for the cord to be useable.Here’s a story of an electrical accident caused by a damaged extension cord.REAL-LIFE EXAMPLEGarrett was a welder. On one job, he was working outside a factory, using a portable arc welder. There was no electrical outlet nearby, so Garrett planned to use an extension cord.But when he went to plug his welding machine’s power cord into the extension cord, the metal case around the power cord plug became energized, and he was fatally electrocuted.An investigation showed two things wrong. The grounding prong on the welder’s power cord was bent, so it slipped outside the connection, and the extension cord’s receptacle was broken, allowing the power plug to enter the extension plug without being grounded.(ask the participants)What did Garrett do wrong?Correct answer: He didn’t check his machine or the extension cord for safety. Truly a double whammy in this case.(From NIOSH Publication “Electrical Safety – Safety & Health for Electrical Trades,” company name withheld)
32 Preventive measure #3: Isolate live electrical parts and equipment Remove covers or guards shielding live electrical parts only for good reason, and with the circuit de-energized.Report missing covers and guards.Ideally, exposed live electrical parts or equipment should be placed where people cannot get at them. One way of accomplishing this is to place the live parts eight feet high or more.But often this isn’t possible, and the live parts are shielded with a cover or, if they can’t be completely enclosed, a guard.Covers and guards should be of a kind that require tools to remove them. And before doing so, you should follow all applicable safety rules, including locking and tagging out the appropriate circuit where necessary.
33 Preventive measure #4: Make sure proper insulation is in place Repair or discard wiring or equipment with damaged insulation.Don’t damage insulation while installing wiring, by piercing it with staples or bending electrical cables too sharply.Insulation protects you against electric shock when you handle wiring and electrical equipment. Be alert for damaged insulation, and either report it to a facilities person, or if you have the authority, discard the equipment or cord on your own.If the worker in the following story had been conscious of the dangers of insulation damage – or if his co-workers had – he might be alive today.REAL-LIFE EXAMPLEDan was a maintenance worker in a factory. Doing his rounds one day, he noticed that a welding machine sitting on a cart had been left on. There was nobody in sight, so Dan, grumbling about forgetful welders, went to turn the machine off.As he touched the metal frame of the machine, an electric shock surged out of the machine and into his body. The powerful shock knocked Dan to the floor and knocked over the cart.When Dan was found a short time later, he was already dead. The machine was examined and it turned out much of its internal insulation was damaged or missing, and there were many cuts and scrapes in the insulation on its cables, as well.Because of the missing insulation, the frame had become energized, a trap just waiting for Dan to come along.(ask the participants)What did Dan do wrong?Correct answer: While most of the fault here lay with the workers who used the machine and never reported the damage to it, Dan should have been more wary of a piece of electrical equipment that he wasn’t familiar with. It wouldn’t have been too cautious for Dan to have disconnected the machine from its power source before touching it.(From NIOSH Publication “Electrical Safety – Safety & Health for Electrical Trades,” company name withheld)
34 Preventive measure #5: Ground electrical systems and tools Grounding creates a low-resistance path to earth for any stray currents.Grounding, as you probably know, creates a path for unexpected voltages and electrical leakages to travel to earth without passing through you or a colleague.These leakages occur because of dirt, wear, damage or moisture. A ground fault happens when stray current passes through the housing of an electrical device to ground, instead of through the safe ground path.Electrical equipment should be grounded if it’s:Within eight feet vertically and five feet horizontally of a floor or walking surface.Within those same distances of grounded metal objects that are accessible to touch.In a wet or damp area.Connected to a power supply by cord and plug and isn’t double-insulated.
35 Preventive measure #6: Use ground fault circuit interrupters (GFCIs) GFCIs are a highly effective means of detecting ground faults and shutting off the dangerous circuit.A GFCI is a fast-acting switch that picks up ground faults by measuring differences in current, and rapidly shuts off the circuit if there is a leakage.Physically, a GFCI may take the form of a duplex receptable, a portable or plug-in or a circuit breaker.Although GFCIs are effective at preventing fatal electrocutions, a worker touching a ground fault may still feel a shock as the device is tripped. So people working around GFCIs may also want to use personal protective equipment (PPE) such as gloves and rubberized soles.GFCIs should always be used when:Electricity is used near water.A user of electrical equipment is grounded, by touching grounded material.Circuits are providing power to portable tools or outdoor receptacles.Temporary wiring or extension cords are in use.
36 Preventive measure #7: Use overload protection devices These are designed to protect equipment and buildings from fire – NOT to protect you from electric shock. GFCIs and other protective equipment are for that.Overload protection devices include such things as fuses and circuit breakers.Although they’re effective at preventing the kind of overheating that can start fires, they’re not aimed at protecting you.That’s because, as we noted earlier, relatively tiny amounts of current, a few milliamps, are enough to shock you painfully or even fatally. By contrast, circuit breakers and fuses will allow many amps of current to flow before they detect an overload and trip or blow.One very important point about circuit breakers and fuses – if they trip or blow, you must find out why. That’s a tip-off that something is wrong along the circuit, and merely putting the circuit breaker back in place or replacing the fuse won’t fix it.Another point: Overload protection devices shouldn’t be used around volatile materials like flammable gases, because they can heat up and sometimes arc or spark.
37 Preventive measure #8: Wear appropriate personal protective equipment (PPE) PPE is your last line of defense against electrical hazard.Use PPE religiously, but don’t expect it to do the job of other preventive measures.If all else fails, PPE is there – or should be – to protect you.PPE for electrical work includes these items:The right hard hat. A Class G (General) hat reduces the danger of contact with low-voltage conductors. These hats are tested at up to 2,200 volts, measured phase to ground. Where there is a risk of contact with high-voltage sources, Class E (Electrical) must be used – or class B, if the hat was made before Class E hats are tested at 20,000 volts. (Note: The voltage that hats are tested at does not indicate the voltage against which the hat protects the wearer.) OSHA requires hard hats be worn where there is risk of head injury from electrical burns.Rubber gloves.Insulating shoes and boots.Safety glasses and/or face shields.Remember, though, that if you or your co-workers have neglected other stages of electrical safety prevention, PPE may not be enough to keep you safe.This point is illustrated very clearly by the following story.REAL-LIFE EXAMPLEBrad worked for the electric company. He was a meter technician most of the time, but during emergency power outages he would double as a lineman.After a storm hit the area and caused widespread outages, Brad was sent to a site where a tree limb had fallen across a 120-volt line. Brad was fully togged out in his safety gear, wearing a hard hat, safety glasses and insulated gloves as PPE.Brad removed the tree branch and climbed the power pole to reconnect the downed wires. As it turned out, the neutral wire in the line had been severed, while the two energized wires were only disconnected from their moorings.As Brad handled the wires, one of the energized wires caught the cuff of his left glove and pulled the cuff down. The live wire contacted the skin of his forearm. He was electrocuted and found dead 30 minutes later hanging by his climbing belt.(ask the participants)What did Brad do wrong?Correct answer: He assumed his safety gloves alone would protect him. It would have been safer to de-energize the line while Brad worked on it. Also, because Brad was working alone, he had no co-worker to call his attention to the fact that the neutral wire was cut, leaving the circuit without a ground.(From NIOSH Publication “Electrical Safety – Safety & Health for Electrical Trades,” company name withheld)
38 Preventive measure #9: Take electrical safety personally Take personal ownership of your safety behavior around electrical conductors.Speak up for safety – don’t just walk on by.This attitude makes all the other preventive measures work.
39 First aid for electrical injury victims Shut off the circuit. Don’t touch someone who is being electrocuted. You may be, too.If you can’t find the circuit control, pry the victim away from the contact point using a non-conductor like a piece of wood.While you’re doing this, get someone else to call 911.The first thing to remember when coming to the aid of a co-worker who’s been shocked or burned by electricity is – don’t double the trouble by getting electrocuted yourself. The victim may still be in contact with the source of the shock. Or even if he or she isn’t, the source of the shock may be close enough to harm you, too.If nobody else is around to call Emergency Services while you’re shutting off the circuit and/or extricating the victim, call 911 yourself after you’ve done the above.You won’t be able to do your job to help an injured co-worker, obviously, if you don’t know where the circuit kill switches are, or where the nearest phone is.
40 First aid (continued)Call the victim to see if he or she is conscious.If so, tell the victim not to move.If the victim is unconscious and not breathing, administer CPR.A conscious victim must not move, even if he or she thinks there’s no serious injury. Electrical injuries, as we’ve noted, can be internal, and the victim may be in shock.Bleeding should be handled by placing a cloth over the wound and applying pressure. Remember to wear gloves when you may be exposed to body fluids.If CPR is needed, it must be started within four minutes of the shock. Be sure that you have trained responders to help until EMS arrives.
41 SummaryElectricity is a powerful and useful force when harnessed; unharnessed, it can kill you.Knowing the major electrical hazards and appropriate preventive measures can keep you and co-workers safe.Take the time to review your workplace now for some of the electrical hazards we’ve described. What precautions will you take to ensure your own safety and that of your colleagues?Be sure you can identify the competent person who represents the electrical trade. Use all your resources to work safely.