December 2018 — Safety is a part of every job but is especially important when working with or around potentially energized electrical equipment. Each year, approximately 1,000 people die in accidents related to electricity. More than half of these deaths occurred in cases where the voltage was less than 600 V. Under the right conditions, as little as 50 V can be fatal.
Most accidents occur because people are unaware of an electrical hazard, or they disregard safety rules. Let’s briefly examine some standard safety practices to observe when working with electricity. Although specific procedures and practices vary from employer to employer, remember that safety is your responsibility. Never trust another person with your safety or your life.
Remember these four key guidelines when working with or around electricity:
- Know the equipment and be aware of the dangers.
- Assume that a circuit is energized until you verify otherwise.
- Follow the rules, using appropriate safety equipment and work practices.
- Be aware of and use proper lockout/tagout procedures.
Avoid Becoming Part of the Circuit
Never place yourself in a position where you might become part of a circuit. If you are not part of the circuit, the electricity will have to find another path to travel. To avoid becoming part of the circuit, you must follow good work practices and use the available specialized safety equipment.
Safety begins with the proper attitude. Be alert for conditions that could indicate an energized component. For example, bare copper or aluminum located in areas of electrical distribution should always be considered energized. Always assume that wiring and related equipment are energized until you can verify otherwise. Also, watch where you place your hands and other parts of your body. When working with or near electrical equipment, always remove jewelry and watches. These items can easily make contact or assist in arcing with energized components. Wear a long-sleeved shirt, roll down the sleeves, and button them at the wrists. Furthermore, avoid wearing wet or damp clothing or clothing that is oil-soaked. Rubber-soled safety shoes will also help to prevent your feet from making contact with electricity. Finally, wear only nonconductive hard hats (plastic, not metal) around overhead electrical equipment.
A variety of safety equipment is designed specifically for use around energized electrical circuits:
Placing a ground cable on a piece of equipment and connecting it to a ground (e.g., water pipe or indicated ground) creates a path of least resistance through the ground cable and reduces the chance that your body will become a path. Some equipment incorporates grounding connections as part of the installation.
When you are required to work with or in close proximity to energized electrical equipment, place insulating material between yourself and the energized components. Wear special rubber gloves designed to withstand high voltages. Protective sleeves and shoulder protection may also be used. You can place rubber matting around or over potentially energized components and on the floor where you will be standing. Some rubber materials contain carbon, a conductor of electricity. Use only those rubber materials specifically designed and labeled for use with energized equipment. It is always important to personally examine protective equipment for damage such as cuts and holes. Flaws will reduce the insulating value of the equipment and place you in danger.
Ground-Fault Circuit Interrupters (GFCI)
Electric tools and equipment (for example, drills, grinders, or saws) should be connected to a GFCI. These devices are designed to protect you if a faulty circuit develops in the equipment. Always inspect your tools’ power cords, extension cords, and drop lights for damage, exposed wires, and altered connections.
When working in wet or hazardous locations, use low-voltage (12 V or 24 V) equipment if possible. Even if a problem develops when using low-voltage equipment, severe injury is unlikely.
The best way to avoid being injured in an electrical accident is to deenergize the circuit. If the circuit is deenergized, there is no voltage source, and the possibility of shock or electrocution is eliminated. OSHA in the U.S. requires a procedure known as lockout/tagout. This method is used to ensure that once a circuit has been deenergized, it cannot be reenergized without the knowledge and permission of the person who established the lockout/tagout. Paragraph 3 of the Canadian Electrical Code 2-304 describes the lockout/tagout requirements in Canada.
Deenergize the Circuit
The circuit should be deenergized at its source. This point will usually be a circuit breaker, control switch, fuse panel, or other switching device. Circuit breakers should be placed in the open position. Large circuit breakers are often racked out (removed from their panel) to ensure that the circuit is deenergized. Control switches should also be placed in the open, or off, position. If the control switches have fuses, the fuses should be removed after the switch has been opened.
Establish the Lockout/Tagout
Once the circuit has been deenergized, the device must be secured in the open position to ensure that no one inadvertently closes the device. Most control switches are equipped with handles that can be locked in the open (deenergized) position. In addition, a red “DANGER” tag should be attached to the device. The tag should indicate that the device is not to be operated. It should also give the name of the person responsible for applying the tag. When you encounter such a tag, do not operate the switch, breaker, or other device.
If you are the person being protected by the lockout/tagout, you should attach your own padlock to the control device, and you should be the only person with the key. Frequently, more than one person will desire protection by deenergizing the same circuit. Devices are available that will allow up to six padlocks on a single control device. Thus, when you have completed your job, you can remove your lock while the other locks remain secure.
Verify the Circuit
Once a circuit has been deenergized, tagged, and locked to your satisfaction, the circuit should be checked at the working point with voltmeters or test meters to verify that it is in fact deenergized. As the establisher of the lockout/tagout, you must be satisfied that the circuit has been deenergized and is properly secured to prevent it from becoming energized. Remember, safety is your responsibility.
If emergency conditions caused by faulty electrical equipment arise, they must be addressed in the following order: extinguish any threat to human safety or human life and then address threats to equipment and other materials.
When a person becomes the path of least resistance for an electric current, that person must first be separated from the source of voltage. This is best accomplished by turning off the power to the circuit involved. Opening a circuit breaker or throwing a switch may be all that is required.
However, if the circuit cannot be deenergized within a short time, the person must be removed from contact with the source. Under no circumstances should you, the rescuer, attempt to touch the person receiving the shock. You too could become part of the circuit. Instead, use an insulating material such as dry wood or dry rope to push or pull the person away from contact with the energized equipment.
Once the person has been separated from the energy source, first aid measures must be taken. The first step is to call for help. Phone 911 or another appropriate emergency contact number. Frequently, the person’s heart stops as a result of the electric shock. If this happens, properly trained personnel should start CPR immediately. If there is evidence of thermal burns, these will also need to be treated by qualified personnel.
Fire or Explosion Involvement
When an electrical fault results in a fire or explosion, the first action is to contact the appropriate emergency response personnel. This may involve calling 911 or the local emergency contact point at your plant. If possible, turn off the power to the equipment involved. Often, simply opening the circuit will cause the fire to go out. If you are trained to do so, you may attempt to put the fire out using an appropriate extinguishing agent.
Electrically energized fires, designated Class C fires, require a nonconducting extinguishing agent such as carbon dioxide. Dry-chemical fire extinguishers can also be used on electrical fires. When faced with an electrical fire, you must use only an extinguisher specified for Class C fires. Keep in mind, though, that once the power to the burning electrical equipment has been shut off, it is no longer a Class C fire, and other extinguishing agents may be used.
This article is adapted from BOMI International’s Electrical Systems and Illumination course, part of the SMA and SMT designation programs. More information regarding this course or BOMI International’s new High-Performance Sustainable Buildings credential (BOMI-HP™) is available by calling 1-800-235-2664. Visit BOMI International’s website, www.bomi.org.