Barring Hazardous Energy

by Todd Proffitt
in TD Talk

Following proper lockout/tagout procedures is crucial to maintaining safety during maintenance.

Safety is always one of the biggest concerns when working in the theatre. In the U.S. the Occupational Safety and Health Administration (OSHA) is responsible for workplace safety. One standard that has a big effect on safety is OSHA standard 1910.147, Control of Hazardous Energy (Lockout/Tagout). It addresses a method for disabling equipment in order to prevent the release of hazardous energy while an employee maintains or services equipment. According to the OSHA fact sheet, “Compliance with the lockout/tagout standard prevents an estimated 120 fatalities and 50,000 injuries each year.” There are some very practical applications for where we should be using lockout/tagout procedures in the theatre, so you should know the basics.

Since the code covers all “hazardous” energy, we need to define the types of energy that we need protection against: Kinetic energy, the mechanical energy found within the moving parts of a machine; Potential energy, pressure stored in hydraulic or pneumatic systems, springs or pressure vessels; Gravity; Electrical energy from generated electrical power, flexible storage devices (batteries) or static sources; Thermal energy, a high or low temperature resulting from mechanical work, radiation, electrical resistance or a chemical reaction. Though we don’t deal with all of these types of energies we do deal with some, and it’s important to control this energy when maintaining equipment.

A lockout/tagout procedure is one in which a device that’s being serviced or maintained is “locked” to prevent it from being energized while it’s being serviced and marked (or “tagged”) to let people know who’s working on it. A lockout device could be placed over the plug of a piece of equipment or on a breaker or switch that controls the equipment. The lockout device will have a place to secure a keyed lock. In most cases the person doing the work should be the only one with the key, so only they can re-energize the equipment. A lockout procedure only needs to be used if the work is not being done near the plug or breaker, and that plug or breaker is out of the control of the person servicing the equipment. The point of a lock is to keep someone from walking by and plugging the equipment back in or turning on a breaker to re-energize the equipment.

There are many different types of lockout devices that can be used. One of the most common is a plug cover, these can be found in a variety of shapes and sizes. There are several circuit breaker covers available when the best solution is to cut power at its source.  There is even a lockout device that will let you lock out an entire breaker box. Switch covers are available that are used to lock out a typical wall switch. There are lockout devices for pneumatic tools and hoses, as well as devices to lock out a valve. Some lighting manufacturers even have a lockout device for their dimmer rack and there are even lockout devices for a rope lock on a counterweight system. More examples of lockout devices can be found via a quick search of Google images:

But you can’t just lock something out, you have to tag it, too. The tag should easily announce the danger involved and list who to contact to remove the lock. Sometimes the tag is a part of the locking device. If not, you will need to provide a tag when locking out the device. Both locks and tags can be purchased at a variety of sources, like Grainger, Amazon or larger home-improvement stores. Often these places will sell a lockout/tagout kit that can easily get you started. If you’re a larger organization, like a school, your environmental health and safety office may already have a kit you can use.

Just locking and tagging out the device does not meet OSHA standards. A written procedure needs to be created for locking and tagging out equipment. Typically the policy will only permit the person who applied the lockout/tagout tag to be the one to remove it. The procedure should identify any users authorized to remove the lock. Someone who was not performing the work should supervise the procedure. The energy control procedures need to be inspected annually and training should be provided to all employees covered by the standard. OSHA provides a template for a procedure here:

There are some typical situations in which you’re going to want to implement a lockout/tagout procedure. Repairing equipment will be a place in which you want to either lock out the plug of the equipment or lock out the circuit breaker. Whenever working on lighting equipment it’s a good idea to have a few plug covers that can handle a stage pin plug. A cover that can handle a plug 3 inches wide, 2 inches deep and 5 inches long should be sufficient for most stage pin plugs. Typically this will be used when working on practicals or lighting installed on a set. The final example would be creating a lockout procedure for a rigging system. Gravity is one type of potential energy that is covered by the standard. Some modern counterweight systems have a way to put a lock on the rope lock, and H&H Specialties has created a lockout and tag all-in-one product.

Creating a lockout/tagout procedure is essential to keeping everyone safe working on stage or in a shop. The best thing to do is educate yourself about the code. The OSHA website is a great source for lockout/tagout info. But don’t forget to check out your state’s lockout tagout procedures, too!

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All the research for this can be found at