Safety tags, locks, and locking devices are used to secure and mark equipment that has been taken out of service. They are applied in such a way that the equipment cannot be reener- gized without first removing the tags and/or locks. For more information about lockout and tagout procedures refer to Chap. 3.
Safety Tags
Safety tags are applied to equipment to indicate that the equipment is not available for ser- vice. They are tags constructed of a durable, environment-proof material. They should be of standardized construction and include a warning that says Do Not Start, Do Not Open, Do Not Close, Do Not Operate, or other such warning. The tag must also indicate who placed it on the equipment and the nature of the problem with the equipment. Figure 2.53 shows tags which are suitable for such an application.
Some manufacturers supply tags with individual employee photographs on them. This type of tag helps to further identify who placed the tag and to personalize the installation.
Tags are to be applied using strong, self-locking fasteners. Nylon cable wraps are suitable for such an application. The fastener must have a breaking strength of not less than 50 lb.
ELECTRICAL SAFETY EQUIPMENT 2.51
Type of warning When to use
Signs Signs should be placed to warn employees about electrical hazards
which may harm them
Barricades Barricades should be used to prevent and limit employee access to work areas where they may be exposed to electrical hazards. Such barriers should be made of nonconductive material such as plastic barrier tape Attendants If signs and/or barricades cannot provide a level of safety sufficient to
protect employees, attendants shall be placed to guard hazardous areas. Attendants shall be familiar with the nature and extent of the hazard so as to adequately warn other employees
2.52 CHAPTER TWO
Locks and Multiple-Lock Devices
Locks are used to prevent operation of equipment that has been de-energized. They must be strong enough to withstand all but the most forceful attempts to remove them without the proper key. If a lock can be removed by any means other than a bolt cutter or the key that fits it, the lock should not be used.
Standard padlocks are normally applied for lockout purposes (Fig. 2.54). Each employee should have a set of padlocks which can be opened only by his or her key. A master key may be kept for emergency situations which require that the lock be opened by someone other than the one who placed it. See Chap. 3 for situations in which safety locks may be removed by someone other than the individual who placed it.
Departments may also have “group” padlocks which are placed by shift personnel and which are keyed to a departmental key. For example, the operations department may have shift operators who remove and restore equipment from service. Equipment may be removed from service during one shift and later returned to service during another shift. In such situations the group lock will be placed by one individual and removed by another. Thus, the group locks will have master keys so that any authorized shift operator can place or remove them.
Multiple-Lock Devices. Sometimes sev- eral workers will need to place a lock on one piece of equipment. This often happens when several crafts are working in the area secured by the lock. In these circumstances, a multiple-lock device is used (Fig. 2.55a). To lock out a piece of equipment, the multiple-lock device is first opened and applied as though it were a padlock. Then the padlock is inserted through one of the holes in the device. The padlock prevents
FIGURE 2.53 Typical tags suitable for tagout purposes. (Courtesy Ideal Industries, Inc.)
FIGURE 2.54 Typical padlocks suitable for lock- out purposes. (Courtesy Ideal Industries, Inc.)
opening of the multiple-lock device which, in turn, prevents operation of the equipment. The devices shown in Fig. 2.55a can accommodate up to six locks; however, multiple-lock devices can be “daisy chained” to allow as many locks as required.
The multiple-lock devices in Fig. 2.55b combine the multiple-lock device with a safety tag. The information required on the tag is written on the tag portion of the device which is then applied to the equipment.
Locking Devices
Some equipment, such as wall switches and molded case circuit breakers, do not readily accommodate locks. In these instances, when lockout is required, a locking device must be used. Figure 2.56a shows locking devices which may be placed over the handle of a molded case circuit breaker and clamped in place. The lock is then installed through the hole left for that purpose. The breaker cannot be operated until the device is removed, and the locking device cannot be removed until the padlock is open.
Figure 2.56b is a similar device which mounts on a standard wall switch. The locking device is first attached to the wall switch with the switch faceplate mounting screws. The switch is moved to the OFFposition and the hinged cover of the device is closed. A padlock is placed through the flange supplied for that purpose.
Devices like the wall switch lockout device can be left in place permanently for switches that are frequently locked out. Although the device shown in Fig. 2.56b can be used to lock the switch in the ONposition, this practice is not recommended.
When/Where to Use Lockout Tagout
Equipment should be locked out and tagged out when it is being serviced or maintained and an unexpected start-up could injure personnel who are working in the area. Thus tags and locks should be placed anytime an employee is exposed to contact with parts of the equip- ment which have been de-energized.
The locks and tags must be applied to all sources of power for the affected equipment. They must be applied in such a way that the equipment cannot be reenergized without first
ELECTRICAL SAFETY EQUIPMENT 2.53
(a) (b)
2.54 CHAPTER TWO
removing the locks and/or tags. See Chap. 3 for more complete information on lockout/tagout procedures. Figure 2.57 shows locks, tags, and multiple-lock devices being applied to elec- trical switching equipment.