Energy. Potential Energy. Stored Energy. Captive Energy. Different terms, but they all mean the same thing: Energy that is lying in wait, ready to pounce, and usually lots of it. Not concerned? You should be. This can kill or maim you before you can yell OUCH!

So, where is this ‘energy’ stuff? As with most things: Right in front of you. Let’s look around:

• Electrical Energy – This one lives in Electrical panels, Dimmers, Cables, Outlets, Circuit Breaker panels, Road Show Disconnects, and just about anything that uses electricity. It can come in the form of a charged-up capacitor, or a hot (active or energized) circuit.
• Mechanical Energy – This can lurk in to-heavy structures, heavy items stored on high shelves (microphone stand bases), unbalanced counterweighted rigging, improperly restrained motorized rigging, and anything hanging above the floor. It also lays in wait with spring-loaded items and overloaded structural elements, you know – that pipe bent back and tied-off that will fly-out and slap you if released.
• Hydraulic Energy– This might be found in an Fire Curtain descent damper, in a fork lift cylinder, or an Orchestra Platform lift column. If a hose breaks or a fitting fails, it can manifest itself as a high pressure spray of fluid that can be driven right through your skin and into your blood stream. This can also come from a ‘power painter’ electric paint brush or a power washer that you might use to scrub-down a shop floor or dumpster with. If you have a trash compactor, this stored energy can move the compactor wedge and crush you. A broken hose can also flail about randomly and strike you. High pressure water lines like used for fire fighting can also be a handful if they get away from you. Make sure you know how to handle these before you try to play Fireman.
• Pneumatic Energy – This is very similar to Hydraulic Energy, they are both part of the ‘Fluid Power’ group. Pneumatic energy is usually stored in air tanks and used to power air tools, air brushes, and run air casters. The high pressure gases used in welding tanks, helium tanks, nitrogen tanks, and CO₂ tanks are also in this category. A broken valve can shoot one of these heavy tanks across a room like a rocket and smash you flat. Welding gases can also ignite and cause an explosion or fire, too. As with the broken hydraulic hose, a high pressure hose with the end spewing gases can swing around and strike-out like a mad viper. Another very dangerous aspect of an unexpected blast of air is that it can drive cleaning solvents, paints, or other fluids out from nooks and crannies and directly into your face. Yet another reason to wear safety glasses!
• Chemical Energy – This is a bit more of an abstract concept to most people, and this is why unsuspecting workers get killed each year. Some things just aren’t meant to mix, and when it comes to various cleaning chemicals and solvents, you can find yourself looking down the barrel of a fire, explosion, or caustic splash faster than you can react. Know what your are mixing and know what it will do. The scene shop is no place to conduct chemistry experiments. READ and UNDERSTAND MSDS’s!
• Thermal Energy – This may be the result of an unexpected exothermic chemical reaction (some epoxies heat-up as they set), or it may be the result of super-cooling due to Dry Ice (frozen CO₂), expansive cooling due to sudden change of pressure like happens with a CO₂ Fire Extinguisher, or the heating of a light source due to the application of electrical energy.

So, what’s a techie to do? When you are working on any system that involves these elements, take precautions to prevent the unexpected release of any of these forms of energy. This requires forethought and planning, and it requires that you provide an effective means to do it.

Enter Lock-Out-Tag-Out (frequently abbreviated: LOTO). It’s not just a good idea, it’s the law. OSHA 29 CFR 1910.269(a)(2) states: "Employees shall be trained in and familiar with the safety-related work practices, safety procedures and other safety requirements in this section that pertain to their respective job assignments. Employees shall also be trained in and familiar with any other safety procedures . . . that are not specifically addressed by this section, but that are related to their work and are necessary for their safety."

What is Lock-Out-Tag-Out?

It is a system of equipment and procedures that is managed to secure equipment from accidental activation or operation when portions of the machine are being serviced, repaired, modified, and/or there are personnel that might be injured by the release of stored energy or the introduction of new energy to the machine or device.

It is usually accomplished by a system of padlocks that are applied to ensure that the power source for a device cannot be activated. This can be a lock on a switch or circuit breaker, a panelboard door, a valve, or lever. The locks are specifically made with only one key. The person locking-out a device is the only one that can unlock it. If several persons must each ‘clear’ a machine to be returned to service, then there may be multiple locks that must be removed before the machine can be operated.

Ball Valve Lock-Out

Circuit Breaker Lock-Out

Cord End Lock-Out

Decora Switch Lock-Out

Standard Toggle Switch Lock-Out

Master Switch Lock-Out

Rope Lock Lock-Out (Courtesy of H&H Specialties)

Get to know more about Lock-Out-Tag-Out, it could save your life.