OSHA’s electrical standards were put in place to help minimize deaths and injuries from dangers such as electrocution, burns, electric shock, fires, and explosions. This 2-hour interactive online course examines the main causes of different types of hazards and details precautions for preventing accidents. It looks specifically at the requirements of 29 CFR 1926, Subpart K – which covers the design characteristics of safe systems for use when installing and using electrical systems. While workers may need additional training based on OSHA standards and the specific hazards of their jobs, RedVector’s Worksite Safety courses can help inject entry-level workers with critical knowledge on a variety of OSHA-regulated safety and health topics.
Upon completion of this module, students should be able to:
While it is common knowledge that electricity is a ubiquitous power source for everything from light bulbs to power tools to critical medical applications, not much attention is paid to the significant hazards it presents when people work in close proximity with it or with it directly. This is especially true at places like construction sites, where there are often a number of temporary electrical power sources set up to power a host of tools, lighting, fans, pumps, and other equipment.
Engineers, power line workers, and electronic technicians – to name a few – work directly with electricity. Others – workers who use power tools, construction crews building near overhead wires – work with it indirectly.
OSHA’s electrical standards were put in place to help minimize deaths and injuries from dangers such as electrocution, burns, electric shock, fires, and explosions. The standard specifies design characteristics of safe systems for use when installing and using electrical systems. We will be looking specifically at the requirements of 29 CFR 1926 Subpart K – Electrical (1926.400 to 1926.449).
The Occupational Safety and Health Administration (OSHA) recognized the important role of the National Electrical Code (NEC) in defining basic requirements for safety in electrical installations by including the entire 1971 NEC by reference in Subpart K of 29 Code of Federal Regulations Part 1926 (Construction Safety and Health Standards). In the final ruling of July 11, 1986, OSHA updated, simplified, and clarified Subpart K, 29 CFR 1926. This eliminated the need to continually reference the NEC and made the standard easier for employers and employees to use and understand. The OSHA revision is also more flexible, eliminating the need to continually keep pace with the NEC. The National Fire Protection Association is responsible for the NEC, which is referred to as NFPA 70. The most updated codes can be found at www.nfpa.org.
The NEC provisions directly related to employee safety are included in the body of the standard itself — making it unnecessary to continue the adoption by reference of the NEC. Subpart K is divided into four major groups plus a general definitions section:
You can find out more about the specific sections of Subpart K by clicking on the links on the above items, and we will cover more about each section later in the course in the third section, General Planning and Controls. For now, we will concentrate on the following:
Wherever there is wide use of electrical circuits, portable power tools and flexible extension cords – such as on a construction site – workers face the risk of encountering electrical hazards, particularly electrical shock. Cords, connectors, receptacles, and other electrical equipment must be properly maintained or it can become hazardous; flexible cords are in general more easily (and more often) damaged than fixed wiring.
In 2010, 76 workers were killed by electrocutions on the job. Statistically, electrical accidents cause nearly 10 percent of workplace fatalities. The truly tragic part is that many of these fatalities could have easily been avoided. The aim of this course is to help you recognize electrical hazards and thus help prevent accidental death and injuries.
Electricity is the flow of energy from one place to another. It is comprised of electrons that travel through a conductor in a closed circuit, and requires a source of power – such as a generator. Operating an electric switch is a lot like turning on a water faucet.
Conductors – such as metals – are materials that offer little resistance to the flow of electric current. Conductors can be (a) bare – a conductor having no covering or electrical insulation whatsoever. (b) covered – a conductor encased within material of composition or thickness that is not recognized as electrical insulation. (c)insulated – a conductor encased within material of composition and thickness that is recognized as electrical insulation.
Insulators – such as porcelain, glass or dry wood – slow the flow of electricity.
Some materials may most often act as either an insulator (i.e., air) or a conductor (impure water), but under certain circumstances can change from one to the other. For instance, air is normally an insulator, but conducts lightning under the right conditions. Dry wood is normally an insulator, but if you wet it, it becomes a conductor. Pure water is not a good conductor – but once impurities are introduced, it becomes a good conductor.
There are four main types of electrical injuries:
Electrocution is a severe electrical shock. The victim suffers the most severe symptoms of contact with electricity and may suffer burns, nerve damage, muscle contractions, cardiac arrest, paralysis, and more. Electrocution most often involves internal and external harm to the body and does result in death.
A shock occurs when your body offers the path of least resistance for completing a circuit.
Shocks can occur when your body completes the path with:
Electricity travels in closed circuits, and its normal route is through a conductor. Electric shock occurs when the body becomes part of the circuit.
When a shock enters the body, it can produce several types of injuries. Electrocution most often involves internal and external harm to the body and does result in death.
If an individual is not killed by that initial jolt, all or part of the body may be paralyzed, either temporarily or permanently. The heart’s rhythms may be disrupted, and the victim may lose the ability to grip or stand. Involuntary movements are also seen often, as are external and/or internal burns.
An electric shock can feel like anything from a slight tingling to immediate heart failure.
A shock’s severity depends on:
1 milliamp (mA) – The approximate level of static shock, like you might get when you touch metal after walking across a carpet on a dry day. Almost never painful, and cannot damage the human body.
5 mA – This is a slight electrical shock that may tingle, but probably won’t be terribly painful. Safety devices called Ground Fault Circuit Interrupters (GFCIs) trip at 5 mA, so in many cases a GFCI-protected circuit will not deliver a dangerous shock.
10 mA – This is the average strength at which a shock will probably test your pain threshold. At this level, you could lose control of your muscles – a dangerous situation if you are on a scaffold or ladder.
50 – 150 mA – A shock from this much current will be extremely painful and can cause serious burns, respiratory arrest, cardiac fibrillation (disrupting your heartbeat) and severe muscle contractions. Some shocks this powerful can be fatal.
1,000 – 4,300 mA – This level of current is rarely encountered if safety measures are in place. This degree of shock causes fibrillation, paralysis, and permanent nerve damage at the least – and death is likely.
10,000 mA – This shock is almost sure to kill you, but if it doesn’t, it will cause complete cardiac arrest, severe burns, nerve damage, and paralysis.
Electrical accidents are usually caused by a combination of three factors:
The metal parts of tools or machines may become energized if there is a cut or fraying in the insulation or power cord of a tool or in the wiring of a machine.
Workers may come in contact with overhead power lines unintentionally because of carelessness or misgauging the overhead distance to the line.
Lightning is a particular threat when working outdoors on high-rise scaffolding or equipment, though its current can also travel through simple household appliances or workman’s tools.
Electrical burns are the most common shock-induced injury, with three types of varying intensity and severity:
Five technicians were performing preventive maintenance on the electrical system of a railroad maintenance facility. One of the technicians was assigned to clean the lower compartment of an electrical cabinet using cleaning fluid in an aerosol can. But he began to clean the upper compartment as well. The upper compartment was filled with live circuitry. When the cleaning spray contacted the live circuitry, a conductive path for the current was created. The current passed through the stream of fluid, into the technician’s arm, and across his chest.
The current caused a loud explosion. Co-workers found the victim with his clothes on fire. One worker put out the fire with an extinguisher, and another pulled the victim away from the compartment with a plastic vacuum cleaner hose.
The paramedics responded in 5 minutes. Although the victim survived the shock, he died 24 hours later of burns.
Source: CDC Workplace Safety & Health, Electrical Safety, Safety and Health for Electrical Trades Student Manual, http://www.cdc.gov/niosh/pdfs/02-123.pdf
This death could have been prevented if the following precautions had been taken:
Electric shock can cause indirect injuries from falls. For one thing, when you receive a shock, you’re – well – shocked, and may lose your balance on a ladder even if only from surprise. For another, if the shock is severe enough, you may lose muscle function and fall because you’re at least temporarily paralyzed.
Exposed electrical parts, wet conditions, damaged equipment and tools, improper personal protective equipment, overloaded circuits, improperly grounded electrical devices, defective insulation and inadequate wiring are some of the usual suspects when an electrical accident occurs.
There are also “clues” that electrical hazards exist:
The two best means of avoiding injury from electrical devices are insulation and grounding.
Insulation – Conductor insulation may be provided by placing nonconductive material such as plastic around a conductor. Insulators help stop or reduce the flow of electrical current, which in turn helps prevent shocks, short circuits and fires. Insulated conductor wires used in equipment grounding are usually either green or green with yellow stripes.
Grounding means establishing a direct connection to a known ground, such as the earth. Grounding creates a low-resistance path from a device to the earth to disperse unwanted current harmlessly. It prevents the buildup of voltages that might lead to an accident. While grounding is a good safety measure, it is a preventive measure and won’t guarantee against a shock. Grounded conductors are usually white-coated wires.
Ungrounded conductors – or hot wires, be any color other than green, white, or gray, but they are usually black or red! Regardless of the color, verify the energy has been isolated(turned off) prior to contacting.
Proper grounding is essential, but doesn’t replace knowledge! It’s important to note that standard 120-volt circuits usually have two wires: A black “hot” wire and a white wire that is neutral and connected to ground. Touching the black wire will cause a shock!
240-volt circuits usually have two wires also. One carries a potential +120 volts; the other is – 120 volts. Touching both of these wires at once will cause a potentially fatal shock!
One measure of control is to isolate electrical parts using guards or barriers and by replacing covers. CFR 1926.403(i)(2) states that “live parts of electric equipment operating at 50 volts or more shall be guarded against accidental contact by cabinets or other forms of enclosures…”
Electrical junction boxes and motor housings are both good examples of using barriers to protect equipment and people.
If a “hot” wire contacts a grounded enclosure, a ground fault results – a condition that trips circuit breakers and blows fuses. Any time you touch part of an electrical circuit, you can sustain a shock if there is a ground fault and your body unwittingly becomes the easiest path to ground.
To prevent your body from becoming the easiest path to ground, a ground fault circuit interrupter (GFCI) can interrupt the circuit and prevent the current from reaching you. The OSHA standard for the construction industry requires the use of GFCIs (more on this important device later).
Other preventive measures, as outlined in 1926.405(b)(1) cover conductors entering boxes, cabinets or fittings, stating they “shall be protected from abrasion, and openings through which conductors enter shall be effectively closed.”
Also detailed are covers and canopies, with the standard stating: “All pull boxes, junction boxes, and fittings shall be provided with covers. If metal covers are used, they shall be grounded.”
These power lines are particularly hazardous because they carry extremely high voltages and are usually not insulated.
Punished by Power!
The main risk from contact with a power line is deadly electrocution. Next are burns and falls from the elevation one might be at working near a line. Finally, using tools and equipment that are liable to come in contact with power lines increases the risk of an accident.
Surprisingly, more than 50 percent of electrocutions are caused by a worker coming in direct contact with energized power lines.
A 38-year-old lineman standing in an aerial bucket was electrocuted while repairing a 13.2-kilovolt power line that had been damaged during an electrical storm. The damaged line was one of two power lines that served a residential area. A third power line supplied a three-phase transformer that served a store and was also internally connected with the other two power lines.
To repair the damaged line, both of the residential power lines were presumed deenergized by opening their respective fused disconnects. However, the third line remained energized to provide power to the store. Voltage back-fed through the transformer on this line and inadvertently energized the line on which a splice was to be made.
Not surprisingly, power line workers face the most risk. Eighty percent of all lineman deaths were at one time attributed to a worker touching a live wire with his/her hand; now, all linemen wear special gloves that protect them from voltages up to 34,500. The majority of today’s power line accidents occur because of failure to maintain proper work distances.
Overhead wires must be deenergized and grounded (or other safeguards put in place) before anyone works with them.
Workers also need to wear (and be trained in the use of) special Personal Protective Equipment (PPE).
Besides PPE, other vital methods of protection when working around power lines include:
Improper or inadequate wiring is another opportunity for electrical disaster. And an electrical hazard is created when, for instance, a wire is too small a gauge for the amount of current it will carry.
An example would be using a portable tool with an extension cord that is too small for the tool. The cord will draw more current than the cord can handle, and the cord could overheat or even cause a fire without tripping the circuit breaker.
Using the correct wire – which will be determined by the operation it is intended for, the building materials it will be used with, the electrical loads, and environmental factors – will forestall most electrical wiring hazards. Fixed cords should be used when possible as they are sturdier than flexible cords. The OSHA standard requires flexible cords to be rated for hard or extra-hard usage, and they must be indelibly marked as such approximately 12 inches for the length of the cord.
Damaged insulation – whether due to age, accidental cuts, abrasion, etc. – can turn a seemingly benign power cord or wire into a silent, deadly floor snake. In all seriousness, when insulation is cut, frayed or otherwise damaged and the inner wires are exposed, the metal parts of a device may become energized if a live wire inside touches them, and if you touch damaged equipment or the damaged portion of the cord, you can receive a shock.
To protect you from harm due to the poor condition of cords and wires:
The NEC and OSHA have specified particular types of flexible cords for use in a construction environment. This rule designates what type of cords must be used for such applications as lights and portable tools.
Hazards are created when cords, cord connectors, receptacles, and cord- and plug-connected equipment are improperly used and maintained. Flexible cords must be connected to devices and to fittings so as to prevent tension at joints and terminal screws. Because a cord is exposed, flexible, and unsecured, joints and terminals become more vulnerable. Flexible cord conductors are finely stranded for flexibility, but the strands of one conductor may loosen from under terminal screws and touch another conductor, especially if the cord is subjected to stress or strain.
A flexible cord may be damaged by activities on the job, by door or window edges, by staples or fastenings, by abrasion from adjacent materials, or simply by aging. If the electrical conductors become exposed, there is a danger of shocks, burns, or fire. A frequent hazard on a construction site is a cord assembly with improperly connected terminals.
When a cord connector is wet, hazardous leakage can occur to the equipment grounding conductor and to humans who pick up that connector if they also provide a path to ground. Such leakage is not limited to the face of the connector but also develops at any wetted portion of it.
Use examples include:
DO NOT use flexible wiring where frequent inspection is impractical or where damage is likely.
DO NOT run flexible cord through holes in walls, ceilings, floors, doorways, windows or hidden areas like conduits or other raceways.
Improper grounding of circuitry and equipment is the most frequent violation of OSHA electrical regulations!
If a system with metal parts isn’t grounded correctly, those parts may become energized and create a serious hazard. Metal parts of appliances or other electronics that are connected to improperly grounded circuits also can become energized, and thus a shock hazard.
Grounded electrical systems are usually connected to a grounding rod placed approximately 6 feet into the earth.
Extension cords with broken wires or plugs may not provide a reliable path to ground. Still another consideration is that electrical systems may be grounded to water pipes, which provide a continuous path to ground when they are made of conductive materials (such as any number of types of metal). However, in renovations and repairs where parts of metal plumbing have been replaced with plastic pipe, the path to ground is interrupted and the result can be electrocutions and fires.
To ensure proper grounding, there are a number of simple controls that will help ensure a safer working environment.
Four components comprise a typical extension cord grounding system:
The OSHA standard requires the following two types of grounds:
A service (or system) ground consists of one white or gray grounded wire (the neutral, or grounded, conductor), which is grounded at the generator and at the service entrance of the building. A service ground generally protects machines, tools and insulation.
An equipment ground furnishes yet another path from equipment (tools or machines) to ground for enhanced worker protection. This type of ground provides additional protection for workers if a malfunction causes the metal parts of a device to become energized.
The only real downside to grounding is that a break in the system can occur without anyone knowing until someone gets a shock, since the break might not be visible to the eye. A device called a ground-fault circuit interrupter (GFCI) – referenced in standard 1926.404(b)(1)(i) – is one way to have backup protection in the event of a ground fault.
A ground-fault circuit interrupter (GFCI) protects workers from shock by matching the amount of current going into an electrical device against the amount returning from the device.
Put another way, a GFCI is a fast-acting circuit breaker that can sense small imbalances in the circuit and immediately shut off the flow of electricity.
The use of these relatively simple, small devices has radically changed the safety of electrical systems for the better by interrupting electric power in as little as 1/40th of a second when the amount of current going out differs from the amount returning by as little as 5mA.
The National Electrical Code (NEC) requires that GFCIs be used when:
While GFCIs successfully reduce electrical hazards on construction sites, they do not eliminate them. We will go into more depth on GFCIs later in the course.
AEGCPs are implemented on construction sites to oversee line-to-line connections (which GFCIs cannot cover) as well as all cord sets, receptacles that are not part of a building or structure, and equipment connected by plug and cord.
Minimum requirements for the proper maintenance of an Assured Equipment Grounding Conductor Program include:
We will go into more depth on this later in the course.
Hazards can result when too many devices are plugged into a circuit. Wires can become overheated, which can cause a fire. Damaged tools that overheat can also cause a hazard, as can lack of overcurrent protection and insufficient wire insulation. Wire insulation can melt, which can cause arcing and a fire where the overload exists – even within a wall.
To prevent too much current in a circuit, circuit breakers or fuses are employed. Both circuit breakers and fuses serve the same purpose: They open a circuit that has become overloaded to shut off the electrical current, preventing damage from spreading throughout the whole system.
If a fuse blows, it is destroyed and must be replaced – as it is designed to be a “weak link” in the system that will melt when it is overloaded, thus containing the damage of the overload.
A circuit breaker serves the same purpose, but has contacts that are designed to open when the circuit becomes overloaded. The circuit can be reset by re-closing the contacts.
While both circuit breakers and fuses may help reduce the probability of a shock to your system, they are designed primarily to protect equipment and an operation’s electrical system. The only device designed specifically to protect people is a GFCI.
Part of the reason the OSHA electrical standard is necessary is that some employers – and workers – will opt to take the easy way out to get something done quickly instead of ensuring their safety and the safety of others by implementing the proper safeguards.
The misuse of equipment can translate into an OSHA violation and a hefty fine, not to mention accidents and injuries. Some of the most common scenarios of equipment misuse are as follows:
Some relatively simple, common sense controls, a bit of knowledge and a lot of awareness can help ensure that the situations described in the list do not occur. We’ll review some of the categories in which construction workers have to be particularly aware.
Use the three-stage safety model: (1) recognize, (2) evaluate, and (3) control hazards. To be safe, you must think about your job and plan for hazards. To avoid injury or death, you must understand and recognize hazards. You need to evaluate the situation you are in and assess your risks. You need to control hazards by creating a safe work environment, by using safe work practices, and by reporting hazards to a supervisor or teacher.
If you do not recognize, evaluate, and control hazards, you may be injured or killed by the electricity itself, electrical fires, or falls. If you use the safety model to recognize, evaluate, and control hazards, you are much safer.
Step 1: Recognize Hazards
The first part of the safety model is recognizing the hazards around you. Only then can you avoid or control the hazards. It is best to discuss and plan hazard recognition tasks with your co-workers.
Sometimes we take risks ourselves, but when we are responsible for others, we are more careful. Sometimes others see hazards that we overlook. Of course, it is possible to be talked out of our concerns by someone who is reckless or dangerous. Don’t take a chance.
Careful planning of safety procedures reduces the risk of injury. Decisions to lock out and tag out circuits and equipment need to be made during this part of the safety model. Plans for action must be made now.
When evaluating hazards, it is best to identify all possible hazards first, then evaluate the risk of injury from each hazard. Do not assume the risk is low until you evaluate the hazard. It is dangerous to overlook hazards. Job sites are especially dangerous because they are always changing. Many people are working at different tasks.
Job sites are frequently exposed to bad weather. A reasonable place to work on a bright, sunny day might be very hazardous in the rain.
The risks in your work environment need to be evaluated all the time. Then, whatever hazards are present need to be controlled.
Once electrical hazards have been recognized and evaluated, they must be controlled. You control electrical hazards in two main ways: (1) create a safe work environment and (2) use safe work practices. Controlling electrical hazards (as well as other hazards) reduces the risk of injury or death.
The following general precautions are among the more important safeguards that should be observed by those using electrical power tools:
Workers who use electric tools must guard against a number of hazards, the most serious being the possibility of electrocution. It is worth repeating that among the chief hazards of electric-powered tools are burns (particularly to the hands) and slight shocks that can cause injuries or even heart failure.
Even a low-voltage shock can cause heart fibrillation and even death, particularly if the shock is prolonged (since power tools tend to be tightly gripped, the duration of the shock is often longer than it might be with objects that are touched accidentally. And remember, even a tiny shock can surprise a worker, causing those on ladders or other elevated work surfaces (scaffolds, roofs) to pull back and lose their balance.
To protect the user from shock, tools must be equipped with either a three-wire cord with ground and be grounded, be double insulated, or be powered by a low-voltage isolation transformer.
Сurrents as low as 10 mA can freeze muscles, rendering someone unable to release the tool. Keep in mind that a tool like a power drill carries 30 times the amount of current required to kill a person!
Anytime an adapter is used to accommodate a two-hole receptacle, the adapter wire must be attached to a known ground. The third prong should never be removed from the plug. Double insulation is more convenient. The user and the tools are protected in two ways: by normal insulation on the wires inside, and by a housing that cannot conduct electricity to the operator in the event of a malfunction.
Some of the important general practices that should be followed when using electric tools include:
All hazards involved in the use of power tools can be prevented by following five basic safety rules:
Temporary lighting should be protected from damage and from contact with workers, and should not be suspended by cords unless designed to do so.
If flexible cords are used to supply temporary lighting, the cords must be approved for hard usage; for example, types “S, SO, ST and STO.”
We have already touched upon grounding and insulation as controls for improper grounding of circuitry and equipment, and the use of GFCIs has been briefly mentioned.
However, ground-fault protection on construction sites is important enough to warrant reviewing some OSHA ground rules:
OSHA ground-fault protection rules and regulations have been determined necessary and appropriate for employee safety and health. Therefore, it is the employer’s responsibility to provide either: (a) ground-fault circuit interrupters on construction sites for receptacle outlets in use and not part of the permanent wiring of the building or structure; or (b) a scheduled and recorded assured equipment grounding conductor program on construction sites, covering all cord sets, receptacles which are not part of the permanent wiring of the building or structure, and equipment connected by cord and plug which are available for use or used by employees.
If ground-fault circuit interrupters are the protective means chosen, OSHA requirements read as follows:
The employer is required to provide approved ground-fault circuit interrupters for all 120-volt, single-phase, 15- and 20-ampere receptacle outlets on construction sites which are not a part of the permanent wiring of the building or structure and which are in use by employees. Receptacles on the ends of extension cords are not part of the permanent wiring and, therefore, must be protected by GFCIs whether or not the extension cord is plugged into permanent wiring.
These GFCIs monitor the current-to-the-load for leakage to ground. When this leakage exceeds 5 mA ± 1 mA, the GFCI interrupts the current. They are rated to trip quickly enough to prevent electrocution. This protection is required in addition to, not as a substitute for, the grounding requirements of OSHA safety and health rules and regulations, 29 CFR 1926. The requirements which employers must meet, if they choose the GFCI option, are stated in 29 CFR 1926.404(b)(1)(ii).
(ii) Ground-fault circuit interrupters. All 120-volt, single-phase, 15- and 20-ampere receptacle outlets on construction sites, which are not a part of the permanent wiring of the building or structure and which are in use by employees, shall have approved ground-fault circuit interrupters for personnel protection. Receptacles on a two-wire, single-phase portable or vehicle-mounted generator rated not more than 5kW, where the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces, need not be protected with ground-fault circuit interrupters.
If the employer chooses to implement an Assured Equipment Grounding Conductor Program (AEGCP), the actual OSHA guidelines are as follows:
The assured equipment grounding conductor program covers all cord sets, receptacles which are not a part of the permanent wiring of the building or structure, and equipment connected by cord and plug which are available for use or used by employees.
The rest of the requirements are stated in 29 CFR 1926.404(b)(1)(iii), but employers may provide additional tests or procedures.
OSHA requires that a written description of the employer’s assured equipment grounding conductor program, including the specific procedures adopted, be kept at the jobsite. This program should outline the employer’s specific procedures for the required equipment inspections, tests, and test schedule.
The required tests must be recorded, and the record maintained until replaced by a more current record. The written program description and the recorded tests must be made available, at the jobsite, to OSHA and to any affected employee upon request. The employer is required to designate one or more competent persons to implement the program.
NOTE: Electrical equipment noted in the assured equipment grounding conductor program must be visually inspected for damage or defects before each day’s use. Any damaged or defective equipment must not be used by the employee until repaired.
Two tests are required by OSHA. One is a continuity test to ensure that the equipment grounding conductor is electrically continuous. It must be performed on all cord sets, receptacles which are not part of the permanent wiring of the building or structure, and on cord- and plug-connected equipment which is required to be grounded. This test may be performed using a simple continuity tester, such as a lamp and battery, a bell and battery, an ohmmeter, or a receptacle tester.
The other test must be performed on receptacles and plugs to ensure that the equipment grounding conductor is connected to its proper terminal. This test can be performed with the same equipment used in the first test.
NOTE: These tests are required before first use, after any repairs, after damage is suspected to have occurred, and at 3-month intervals. Cord sets and receptacles which are essentially fixed and not exposed to damage must be tested at regular intervals not to exceed 6 months. Any equipment which fails to pass the required tests shall not be made available or used by employees.
As mentioned much earlier in the course, when OSHA needed help in 1970 devising standards to keep workers safe from the myriad of electrical hazards, it noted that experts in electrical safety turned to the National Electrical Code (NEC). OSHA recognized the important role of the NEC by co-opting the entire 1971 NEC by reference into Subpart K of 29 Code of Federal Regulations Part 1926 (Construction Safety and Health Standards).
To review, Subpart K is divided into four major groups:
We will address each of these separately.
Following are steps the employer must take to ensure the safety of electrical equipment…but obviously, these same checkpoints can serve as a common-sense guide for employees! Review the lists below and double-check that the requirements are met. While the lists are by no means complete, it can’t hurt to read them – and it may save your life.
The safety of equipment must be determined by the following:
Live parts of electric equipment operating at 50 volts or more must be guarded against accidental contact.
Guarding of live parts must be accomplished as follows:
Entrance to rooms and other guarded locations containing exposed live parts must be marked with conspicuous warning signs forbidding unqualified persons to enter.
For overcurrent protection of circuits rated 600 volts, nominal, or less.
An employer must not allow an employee to work near any part of an electric power circuit that the employee could contact in the course of work, unless the employee is protected against shock. This means the circuit must be deenergized and grounded or otherwise guarded by insulation or other means.
Even before work is begun, the employer must determine where any part of an exposed or concealed energized electric power circuit is located. This is necessary because a person, tool or machine could come into physical or electrical contact with the electric power circuit. The employer is required to advise employees using jack hammers, underground drilling equipment or hand tools that may contact a line must be provided with insulated protective gloves or insulated protective boots if required by a manufacture.
Reference 1926.417 breaks this requirement down into four simple points:
Employer must provide barriers or other means of guarding to ensure that workspaces for electrical equipment are not used as passageways when energized parts of electrical equipment are exposed.
Work should be preplanned, hazard warnings should be posted near electrical equipment, and walkways and similar working spaces should be kept clear of electric cords.
Only qualified persons may work on electric circuit parts or equipment that has not been de-energized. Those people must be specially trained to be familiar with the proper use of special precautionary techniques, PPE, insulating and shielding materials, and insulated tools.
As mentioned, any live parts an employee might come in contact with must be de-energized before the employee works near or on them, unless the employer can show that de-energizing would actually introduce a greater (or additional) hazard or that it is infeasible because of operating limitations or the equipment design.
When exposed live parts are not de-energized, other safety precautions must be taken to protect employees.
The employer must ensure that all wiring components and utilization equipment in hazardous locations are maintained in a dust-tight, dust-ignition-proof, or explosion-proof condition without loose or missing screws, gaskets, threaded connections, seals, or other impairments to a tight condition.
Unless identified for use in the operating environment, no conductors or equipment can be located:
Any time you are working with or around electricity, there are a series of hazards that can cause injury. To this end, your employer and OSHA have certain responsibilities to carry out and must implement certain controls to help prevent accidents. However, nothing will take the place of your own awareness… be sure to wear the proper PPE, use good work practices, and stay alert!