What is the best way for employees to protect against electrical hazards?
Most electrical accidents result from one of three factors:
- Unsafe equipment or installation
- Unsafe environment
- Unsafe work practices
Accidents and injuries can be prevented through the use of insulation, guarding, grounding, electrical protective devices, and safe work practices.
What protection does insulation provide?
Insulators such as glass, mica, rubber, or plastic used to coat metals and other conductors help stop or reduce the flow of electrical current. This helps prevent shock, fires, and short circuits. To be effective, the insulation must be suitable for the voltage used and conditions such as temperature and other environmental factors like moisture, oil, gasoline, corrosive fumes, or other substances that could cause the insulator to fail.
What is grounding and what protection does it offer?
“Grounding” a tool or electrical system means intentionally creating a low-resistance path that connects to the earth. This prevents the buildup of voltages that could cause an electrical accident.
Grounding is normally a secondary protective measure to protect against electric shock. It does not guarantee that you won’t get a shock or be injured or killed by an electrical current. It will, however, substantially reduce the risk, especially when used in combination with other safety measures discussed in this booklet. 29 CFR, Part 1910.304, Subpart S, Wiring Design and Protection, requires at times a service or system ground and an equipment ground in non-construction applications.
A service or system ground is designed primarily to protect machines, tools, and insulation against damage. One wire, called the “neutral” or “grounded” conductor, is grounded. In an ordinary low-voltage circuit, the white or gray wire is grounded at the generator or transformer and at the building’s service entrance.
An equipment ground helps protect the equipment operator. It furnishes a second path for the current to pass through from the tool or machine to the ground. This additional ground safeguards the operator if a malfunction causes the tool’s metal frame to become energized. The resulting flow of current may activate the circuit protection devices.
What are circuit protection devices and how do they work?
Circuit protection devices limit or stop the flow of current automatically in the event of a ground fault, overload, or short circuit in the wiring system. Well-known examples of these devices are fuses, circuit breakers, ground-fault circuit interrupters, and arc-fault circuit interrupters.
- Fuses and circuit breakers open or break the circuit automatically when too much current flows through them. When that happens, fuses melt and circuit breakers trip the circuit open. Fuses and circuit breakers are designed to protect conductors and equipment. They prevent wires and other components from overheating and open the circuit when there is a risk of a ground fault.
- Ground-fault circuit interrupters, or GFCIs, are used in wet locations, construction sites, and other high-risk areas. These devices interrupt the flow of electricity within as little as 1/40 of a second to prevent electrocution. GFCIs compare the amount of current going into electric equipment with the amount of current returning from it along the circuit conductors. If the difference exceeds 5 milliamperes, the device automatically shuts off the electric power.
- Arc-fault devices provide protection from the effects of arc-faults by recognizing characteristics unique to arcing and by functioning to deenergize the circuit when an arc-fault is detected.
What should employees do if a co-worker “freezes” to a live electrical contact?
If a co-worker is “frozen” to a live electrical contact, employees should shut off the current immediately. If this is not possible, they can use boards, poles, or sticks made of wood or any other nonconducting materials and safely push or pull the person away from the contact. It’s important to act quickly, but employees should remember to protect themselves as well from electrocution or shock.
How is static electricity hazardous?
Static electricity also can cause a shock, though in a different way and generally not as potentially severe as the type of shock described previously. Static electricity can build up on the surface of an object and, under the right conditions, can discharge to a person, causing a shock. The most familiar example of this is when a person reaches for a door knob or other metal object on a cold, relatively dry day and receives a shock.
However, static electricity also can cause shocks or can just discharge to an object with much more serious consequences, as when friction causes a high level of static electricity to build up at a specific spot on an object. This can happen simply through handling plastic pipes and materials or during normal operation of rubberized drive or machine belts found in many worksites.
In these cases, for example, static electricity can potentially discharge when sufficient amounts of flammable or combustible substances are located nearby and cause an explosion. Grounding or other measures may be necessary to prevent this static electricity buildup and the results.
Avoid Electrical Safety Mistakes and Violations
In October 2013, the preliminary figures for OSHA’s top 10 violations for FY 2013 revealed thousands of violations related to electrical safety. Coming in at number five was “electrical, wiring methods” with 3,452 violations. Common issues involved:
- Problems with flexible cords and cables, boxes, and temporary wiring
- Poor use of extension cords
- Using temporary wiring as permanent wiring
At number eight was “lockout/tagout,” with 3,254 violations ranging from poor or no energy control procedures to inadequate worker training, and incomplete inspections. “Electrical, general” took the number nine spot (2,745 violations) for exposure to electric shock and electrocution.
One of the best ways to improve the overall compliance of your safety program is to take a close look at the electrical safety violations for which OSHA is citing companies, including yours. By taking advantage of these “hard lessons learned” you can use the information to identify gaps in your current program and share what you’ve learned with senior management, facility staff, and your audit team.