Even though wiremen, electricians and other electrical workers are familiar with the dangers of electricity and energized equipment, they far too often overlook or neglect simple, essential safety practices. This behavior results in countless preventable injuries and over 100 fatalities each year. Failure to comply with appropriate lockout/tagout (LOTO) protocol leads to many of these incidents.
To provide an electrically safe working condition as prescribed by the National Fire Protection Association 70E, Standard for Electrical Safety, personnel must take several steps. These include preparation procedures such as identifying all energy sources including stored energy, locating disconnecting means and identifying protocols for releasing stored energy.
According to the standard, once the prep is complete, the first step in implementing the LOTO is to notify personnel. This means, prior to beginning work, all persons in the area (including “affected” individuals and “authorized” employees) must be made aware that a LOTO is going to take place. An affected individual is anyone who works in or around the service or maintenance area. Authorized employees are those exposed to the hazard or those who perform the service or maintenance. Affected individuals should know the power will be off and the reason why. During the LOTO, they should not attempt to operate any of the affected equipment. It is also imperative that all appropriate persons are familiar with all energy sources and their locations.
Once personnel have been notified, it is important to disconnect and de-energize equipment. Immediately after that, check for residual energy that may remain stored in the equipment or circuits. Always discharge capacitors and short-circuit, high-capacitance elements, and remember that LOTO procedures can be used for other forms of energy as well. This may include the release of stored hydraulic, pneumatic or mechanical energy.
After all stored energy is released, apply locks and/or tags. All employees must apply their lock or tag to all disconnecting means used to de-energize the circuit. When using a tag without a lock, another safety measure must be used. Once this step has been completed, verify that everything up to this point has been done correctly.
During the verification process, first attempt to operate then check that the equipment or circuit is de-energized and cannot be re-energized with the lock or tag in place. Confirm all switches and/or other disconnecting means can be operated with the lock or tag in place. Do not proceed until this is verified.
Immediately following this step, test for the absence of voltage using a voltage detector. It is important to select proper working equipment. A voltage detector itself must be tested before and after each use. Check the continuity of the test leads or voltage against a known source. For additional protection, always wear the appropriate personal protective equipment (PPE) while testing.
Upon completing the verification process, it is not safe to perform work. The need for protective grounds must be determined and, if needed, applied before any work can begin. Also be aware that the potential for induced voltage or other stray current exists. Use grounds rated for the maximum available fault current for the time necessary to clear the fault. It is safe to perform work only once these steps have been completed.
Now, consider this real-life example: an electrician was electrocuted while working on junction box to connect two air conditioning units and service a lighting panel. The electrician followed proper LOTO procedures. However, having completed the wiring connection for the lighting service, the electrician instructed the job foreman to throw on the breaker to the lighting service while he continued to run the wiring for the two air conditioning units. Instead, the foreman threw on the breakers for both the lighting service and the air conditioning services.As the foreman threw on the breakers, the electrician was holding the wiring for the air conditioning service and was electrocuted. What went wrong?
Energized equipment should be locked and tagged from the start of service/maintenance until all work is completed. Additionally, in this case, all relevant individuals were not aware of all energy sources and their locations.
Employers also should have a LOTO program, written procedures and provide necessary equipment to protect employees. This includes locks, tags, diagrams and the appropriate PPE. LOTO training should also be offered to all workers exposed to electrical hazards.