Back to Basics is a weekly feature that highlights important but possibly overlooked information that any EHS professional should know. This week, we examine electrical safety.
Some workers may have more exposure to electrical hazards than others, but all workers should understand the dangers of electricity and how to take the proper precautions.
The Occupational Safety and Health Administration (OSHA) has several standards that address electrical safety. For general industry, 1910 Subpart I – Personal Protective Equipment, 1910.137 covers Electrical Protective Equipment and 1910 Subpart R – Special Industries, 1910.269 addresses Electric Power Generation, Transmission, and Distribution. And the entirety of 1910 Subpart S is dedicated to Electrical Safety.
There are also relevant maritime standards: 1915 Subpart L – Electrical Machinery, 1915.181 addresses electrical circuits and distribution boards and 1917 Subpart G – Related Terminal Operations and Equipment, 1917.157 covers battery charging and changing.
OSHA also revised the Electric Power Generation, Transmission and Distribution Standard (29 CFR 1926, Subpart V) to make it more consistent with the general industry standard; it also revised the construction and general industry requirements.
Electrical hazards in construction are also covered in OSHA’s Construction Industry standards 29 CFR 1926, Subpart K – Electrical.
Hazard Recognition
The following hazards are the most common causes of electrical injuries: Contact with power lines, lack of ground-fault protection, path to ground missing or discontinuous, equipment not used in manner prescribed, and improper use of extension and flexible cords.
Contact with power lines
Power lines, whether overhead or buried underground, are hazardous because they carry extremely high voltage. According to OSHA’s Construction e-tool, fatal electrocution is the main risk, but burns and falls from elevations are also hazards. Using tools and equipment that can come in contact with power lines increases the risk.
Types of equipment that can contact power lines include:
- Aluminum paint rollers
- Backhoes
- Concrete pumpers
- Cranes
- Long-handled cement finishing floats
- Metal building materials
- Metal ladders
- Raised dump truck beds
- Scaffolds
Take the following steps to avoid hazards:
- Look for overhead power lines and buried power line indicators. Post warning signs.
- Contact utilities for buried power line locations.
- Stay at least 10 feet away from overhead power lines.
- Unless you know otherwise, assume that overhead lines are energized.
- De-energize and ground lines when working near them. Other protective measures include guarding or insulating the lines.
- Use non-conductive wood or fiberglass ladders when working near power lines.
Lack of ground-fault protection
Normal use of electrical equipment at a construction site causes wear and tear that results in insulation breaks, short circuits, and exposed wires. If there is no ground-fault protection, these can cause a ground fault that sends current through the worker’s body, resulting in electrical burns, explosions, fire, or death.
Do the following to avoid hazards:
- Use ground-fault circuit interrupters (GFCI) on all 120-volt, single-phase, 15- and 20-ampere receptacles, or have an assured equipment grounding conductor program (AEGCP).
- Follow manufacturers’ recommended testing procedure to ensure GFCI is working correctly.
- Use double-insulated tools and equipment, distinctively marked.
- Use tools and equipment according to the instructions included in their listing, labeling, or certification.
- Visually inspect all electrical equipment before use. Remove from service any equipment with frayed cords, missing ground prongs, cracked tool casings, etc. Apply a warning tag to any defective tool and do not use it until the problem has been corrected.
Path to ground missing or discontinuous
If the power supply to the electrical equipment at a site is not grounded or the path has been broken, fault current may travel through a worker’s body, causing electrical burns or death. Even when the power system is properly grounded, electrical equipment can instantly change from safe to hazardous because of extreme conditions and rough treatment.
The following steps will help you avoid hazards:
- Ground all power supply systems, electrical circuits, and electrical equipment.
- Frequently inspect electrical systems to ensure that the path to ground is continuous.
- Visually inspect all electrical equipment before use. Take any defective equipment out of service.
- Do not remove ground prongs from cord- and plug-connected equipment or extension cords.
- Use double-insulated tools and equipment, distinctively marked.
- Ground all exposed metal parts of equipment.
- Ground metal parts of the following non-electrical equipment, as specified by standard 29 CFR 1926.404(f)(7)(v):
- Frames and tracks of electrically operated cranes
- Frames of non-electrically driven elevator cars to which electric conductors are attached
- Hand-operated metal shifting ropes or cables of electric elevators
- Metal partitions, grill work, and similar metal enclosures around equipment of over 1kV between conductors
Equipment not used in manner prescribed
If you don’t use electrical equipment in the ways for which it was designed, you can no longer depend on safety features built in by the manufacturer. This could damage your equipment and cause employee injuries.
Common examples of misused equipment include:
- Using multi-receptacle boxes designed to be mounted by fitting them with a power cord and placing them on the floor.
- Fabricating extension cords with ROMEX(R) wire.
- Using equipment outdoors that is labeled for use only in dry, indoor locations.
- Attaching ungrounded, two-prong adapter plugs to three-prong cords and tools.
- Using circuit breakers or fuses with the wrong rating for over-current protection (e.g., using a 30-amp breaker in a system with 15- or 20-amp receptacles). Protection is lose because it will not trip when the system’s load has been exceeded.
- Using modified cords or tools (e.g., removing ground prongs, face plates, insultation, etc.).
- Using cords or tools with worn insulation or exposed wires.
The following steps will help you avoid hazards:
- Use only equipment that is approved to meet OSHA standards
- Use all equipment according to the manufacturer’s instructions
- Do not modify cords or use them incorrectly
- Be sure equipment that has been shop fabricated or altered is in compliance
Improper use of extension and flexible cords
Normal wear and tear on extension and flexible cords at your work site can loosen or expose wires, creating hazardous conditions. You have an increased risk of contacting electrical current if you use cords that are not 3-wire type, not designed for hard usage, or that have been modified.
Do the following to avoid hazards:
- Use factory-assembled cord sets.
- Use only 3-wire type extension cords.
- Use only extension cords that are marked with a designation code for hard or extra-hard usage.
- Use only cords, connection devices, and fittings that are equipped with strain relief.
- Remove cords from receptacles by pulling on the plugs, not the cords.
- Continually audit cords on-site. Any cords found not to be marked for hard or extra-hard use, or which have been modified, must be taken out of service immediately.
OSHA provides a list of references that offer possible solutions you can implement to reduce or eliminate the risk of injury associated with electrical work.