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.
The facility owner is ultimately responsible for safety at their site and must communicate known hazards covered by NFPA 70E to the contracted worker(s).In addition, the owner must report any contract employee’s safety violations to the contract employer.
From an electrical safety perspective, always consider the electrical system and equipment to be energized (live) before beginning any work. At a minimum, the electrical work section of the job specific safety plan should address the following topics:
- Location of disconnects and the lock-out/tag-out procedure
- Indicate where the system is to be grounded
- Person verifying lock-out and utility grounds
- Location of personal grounds
• De-energization- all of the following conditions must be met:
- Proper lock-out/tag-out procedures are followed
- The electrical system is tested to be de-energized
- Grounds are in place
- Identify the person responsible for switching
- Is the switching procedure agreed upon by all stakeholders
- Does a switching form need to be signed by the customer
• Personal Protective Equipment (PPE) Requirements
- Identify the appropriate PPE required
- Where is the required PPE located
• Electric Power Tools
- Tools should be operated for their intended purpose and within their design limitations.
- Electrical tools should be attached to a ground fault current interrupter (GFCI).
- Appropriate personal protective equipment should be worn
- Insulated tools are also required if testing or troubleshooting is to be performed on energized equipment
- Work should be performed in dry, well-lit areas
• Onsite Authority
- Identify the person responsible for jobsite audit(s)
- Are regularly-scheduled onsite safety meetings required?
- Does the customer want additional written procedures?
For protection against shock, power tools should have a three-wire cord with ground and be grounded. Should an adapter be used to accommodate a two-hole receptacle, NEVER remove the third prong. The adapter wire must be attached to a known ground.
The goal of any company’s workplace safety program is to enable workers to be able to go home safely at the end of their day. Safeguard against electric shock; don’t take shortcuts when it comes to safety.
Allen Hajian is the director of safety and environment services – North America for Schneider Electric, an IEC National Platinum Industry Partner.