Locking and Tagging
Why it’s the best way to create an electrically safe work condition
NFPA Journal®, July/August 2011
Establishing an electrically safe work condition is the only personal protection method that guarantees there is no electric shock or arc-flash hazard. No electric power equals no electrical hazard, which means that workers are protected from accidental activation of equipment and subsequent injury or death. Article 120 of NFPA 70E covers the process of establishing an electrically safe work condition, a key component of which is controlling hazard electrical energy — or, as it is more commonly called in the industry, lockout/tagout.
The 2009 edition of NFPA 70E provides three methods of controlling hazardous electrical energy, one of which is the use of an individual qualified employee control procedure to ensure that the source of electrical energy is disconnected to establish an electrically safe work condition.
The individual qualified employee control procedure allows those doing minor maintenance, servicing, adjusting, cleaning, and inspection tasks to operate a local disconnecting means before placing equipment into an electrically safe work condition without locking and tagging the circuit disconnecting means.
To ensure that other employees do not inadvertently operate the disconnecting means, the procedure can only be implemented where the disconnecting means is adjacent to the conductor, circuit parts, and equipment being worked on, and where it is clearly visible to the person doing the work. Work performed under this procedure cannot extend over multiple shifts.
As practical as this may seem, this procedure does not ensure that the disconnecting means will remain open using a locking device with a tag prohibiting unauthorized operation. Not only are the terms “adjacent” and “clearly visible” subject to interpretation, but the chance of human error increases where the disconnecting means can be inadvertently operated by other employees.
If you compare the lockout and tagging requirements of Section 120.2(D) of NFPA 70E to those found in the OSHA requirements of 29 CFR Part 1910 Subpart S, you will note that the OSHA regulations do not include the option of using an individual qualified employee control procedure. The closest practice to the individual qualified employee control procedure in OSHA’s regulations is found in 29 CFR, Part 1910, Subpart S 1910.147(a)(2)(iii)(A), which covers de-energizing cord- and plug-connected equipment where the employee servicing the equipment has exclusive control of the plug. Where this method of interrupting the power to equipment is used, lockout and tagging is not required.
The individual qualified employee control procedure has been recognized in NFPA 70E since the 1995 edition. However, the 2012 edition will mark the end of this procedure as an acceptable means of controlling hazardous energy. Based on the substantiation that the OSHA regulations do not recognize this method, the Technical Committee on Electrical Safety in the Workplace accepted a proposal to delete this provision. Several public comments supporting retention of the procedure were submitted, but the committee maintained its position to be in line with OSHA. Locking and tagging the disconnecting means is the best way of ensuring an electrically safe work condition.
Jeffrey Sargent is NFPA's senior electrical specilist and is staff liason for NFPA 70E.