- Features | June 27, 2013
Shocking Statistics ... Don't Be One!
While arc flash awareness has been growing over the past decade (as well it should), the dangers of shock and electrocution should not be overlooked. According to the most recent statistics from the Occupational Health and Safety Administration (OSHA), electrocution is the second leading cause of construction site fatalities in the U.S. In an average eight-hour day, 16 workers require time off the job to recover due to electrically-induced injuries.
How Shock Occurs
Electrical current travels the path of least resistance; it either finds a path to ground or another conductor to complete its circuit. Keep in mind that electricity disperses in various ways across different surfaces. If there is a voltage difference between two conductive objects, and a third conductive object bridges the gap to complete the circuit, the current will flow across. If the third conductor is a person, they will receive an electric shock. Electricity will flow through their body as they become part of the current’s path. A person can receive a shock by being in contact with:
- Both wires of an electric circuit;
- One wire of an energized circuit and the ground; and
- A metal part that accidentally becomes energized, for example, a break in its insulation.
Protective devices (circuit breakers and fuses) are installed in electrical systems to protect against a short circuit or a major fault current. Unfortunately, a person can be electrocuted below the point at which the protective device would operate. Heart fibrillation, severe burns, and death are possible between 0.1 and five amps, which is well below the rating that fuses and circuit breakers would operate to protect equipment.
No Shortcuts to Safety
Does the Federal Aviation Administration require pilots and ground crews to perform safety and mechanical checks only on coast to coast flights? Obviously, the answer is no. The same can be said for OSHA and National Fire Protection Association (NFPA) 70 requirements relative to electrical safety. No shortcuts; no matter how complex or basic the work.
A job-specific safety plan should be developed for each project based upon the work scope. It is not the same as a company's overall Electrical Safe Work Practices (ESWP) policy, as defined by NFPA 70E. Development of an ESWP policy is one of five steps to comply with the requirements of NFPA 70E. However, the job-specific safety plan should be consistent with the requirements of the customer's ESWP and apply to all employees, including contractors, involved with the job. Depending upon the complexity of the work scope, a job specific safety plan may cover a variety of topics, as shown in the chart below.
Example of job-specific topics addressed for complex project:
NFPA 70E-2012, Section 110.1(A) states that hiring contractors to perform electrical work does not absolve the owner of the facility (host employer) from assuring compliance to safe work practices.