Hazardous Energy: What, Why & How Dangerous Is It?

In workplaces across America, various energy sources pose significant risks to workers, particularly those involved in servicing and maintaining machinery and equipment. This energy—whether electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or from other sources—can be extremely hazardous when not properly controlled. In fact, improper handling of hazardous energy can lead to severe injuries, including electrocution, crushing, burns, amputations, or even death. Understanding what hazardous energy is, why it's dangerous, and how to manage it is essential to ensuring worker safety.

What Exactly Is Hazardous Energy?

Hazardous energy refers to the energy present in machines and equipment that can be harmful if released unexpectedly. This includes energy in electrical circuits, pressurized hydraulic or pneumatic systems, mechanical components, chemical reactions, and thermal processes. When a machine is turned off, hazardous energy may still be stored within the system, waiting to be released unless proper precautions are taken.

Hazardous energy comes in many forms, such as:

Electrical Energy: Found in live wires, circuits, and equipment.
Mechanical Energy: Present in moving parts, springs, and other mechanical components.
Hydraulic Energy: Stored in pressurized fluids within hydraulic systems.
Pneumatic Energy: Stored in compressed air or gases.
Chemical Energy: Released during chemical reactions, such as in batteries or industrial processes.
Thermal Energy: Related to heat, such as from steam systems or heated machinery.

Hazardous energy is a necessary part of operating machines and equipment in various industries. Without it, modern manufacturing, construction, and many other sectors could not function efficiently. The key is to manage this energy safely to prevent accidents.

If not controlled, hazardous energy can lead to catastrophic injuries, such as:

Electrocution: From contact with live electrical components.
Crushing: From machinery that suddenly moves or releases energy.
Burns: From hot surfaces or chemical reactions.
Amputations: From moving parts that trap or sever limbs.
Fractures and Lacerations: From flying debris or sudden impacts.

What Creates Hazardous Energy?

Hazardous energy is generated as a byproduct of the normal operation of machines and equipment across various industries. This energy is inherent in the functioning of these systems and is necessary for tasks such as powering motors, moving mechanical parts, pressurizing fluids, and conducting chemical processes. However, the same energy that enables productivity can become dangerous if not properly controlled.

Active Operation of Machinery

During the active operation of machinery, various forms of energy are continuously at play. For example, in a manufacturing plant, electrical energy powers conveyor belts, mechanical energy drives moving parts, and thermal energy may be involved in heating processes. When machines are running, energy is being converted from one form to another—such as electrical energy being converted into mechanical motion. This continuous flow and transformation of energy are what keep machines functioning, but they also create the potential for hazards if something goes wrong.

Stored Energy in Deactivated Systems

Even when machines are turned off, they may still harbor dangerous amounts of stored energy. This is especially true for systems that use pressurized fluids or compressed springs. For example:

Compressed Springs: Springs store mechanical energy when compressed and can release that energy suddenly, causing parts to move unexpectedly.
Pressurized Tanks: Hydraulic or pneumatic systems often contain pressurized fluids or gases. Even when the system is turned off, the stored pressure can be released explosively if a valve is opened or a line is disconnected without proper precautions.

This residual energy can pose significant risks during maintenance or repair activities. If not properly de-energized, these systems can suddenly reactivate or release stored energy, endangering anyone nearby.

Residual Energy in Static Forms

Hazardous energy can also exist in more subtle, static forms, such as:

Residual Heat in Boilers or Furnaces: Even after a system is shut down, residual heat may remain in the equipment. Workers coming into contact with surfaces that are still hot can suffer severe burns.
Residual Pressure in Hydraulic Lines: Hydraulic systems may retain pressure even after being turned off. This pressure can cause components to move or fluids to be ejected with force, leading to crushing injuries or lacerations.

This static energy can be deceptive because the machinery may appear inactive, but the hidden dangers remain. Workers must be aware of these potential hazards and ensure that all energy sources are fully neutralized before starting any work.

In some cases, hazardous energy can accumulate due to malfunctions or improper operation of equipment, such as:

Electrical Short Circuits: A malfunction in an electrical system can cause energy to build up unexpectedly, leading to sparks, fires, or electrocution.
Mechanical Jams: Machinery that becomes jammed can store mechanical energy as parts are forced into unnatural positions. When the jam is cleared, the stored energy can be released suddenly, causing parts to move with dangerous force.

These situations highlight the importance of routine maintenance and proper safety checks to identify and address potential issues before they result in hazardous energy release. Given the various ways hazardous energy can be created, it is crucial for workplaces to implement stringent energy control procedures.

How Can Hazardous Energy Be Controlled?

The most effective way to control hazardous energy is through Lockout/Tagout (LOTO) procedures. LOTO ensures that machinery is properly shut off and cannot be restarted until maintenance is completed. OSHA’s standards for controlling hazardous energy (29 CFR 1910.147) outline detailed steps for safely de-energizing equipment and ensuring it remains de-energized until work is complete.

Which Industries Use Hazardous Energy?

Hazardous energy is prevalent in many industries, including:

Manufacturing: Machinery, assembly lines, and automated systems
Construction: Heavy equipment, power tools, and building systems
Chemical Processing: Industrial reactors, pipelines, and storage tanks
Utilities: Electrical grids, water treatment, and waste management
Transportation: Rail systems, automotive manufacturing, and shipping

Workers in specific roles within these industries are particularly at risk from hazardous energy, such as:

Craft Workers: Electricians, plumbers, and carpenters
Machine Operators: Those who run and maintain equipment
Maintenance Workers: Responsible for servicing and repairing machinery
Laborers: Performing routine tasks that require interaction with machinery

Who is Most At Risk From Hazardous Energy?

While hazardous energy primarily poses risks to workers, nearby communities can be affected by large-scale industrial accidents, such as chemical spills or explosions. Proper safety protocols and emergency response plans are essential to minimize these risks.

States with heavy industrial and manufacturing activities, such as Texas, California, and Ohio, tend to report higher rates of injuries and deaths related to hazardous energy. However, this can vary annually and depends on the enforcement of safety regulations.

One of the most dangerous forms of hazardous energy is electrical. According to OSHA, electrocution is among the “Fatal Four,” one of the top causes of fatalities in industries such as construction. Similarly, the Electrical Safety Foundation reports that 48% of all electrical fatalities between 2011 and 2022 were caused by working on or near energized wires or parts, while 6% were caused by a failure of the lockout/tagout safety devices.

How Long Does Hazardous Energy Exposure Take to Be Dangerous?

Exposure time varies, but hazardous energy can cause injury in an instant. For instance, a brief contact with live electrical wiring can be fatal, and a sudden release of hydraulic pressure can crush or amputate limbs within seconds.

How Close Does a Worker Have to Be to Hazardous Energy to Be in Danger?

The proximity to hazardous energy varies depending on the type. For example, workers need to be very close to mechanical and hydraulic systems to be at risk, while electrical hazards can pose a risk from several feet away due to potential arcing.

Protecting Workers from Hazardous Energy

Hazardous energy is an integral part of many industries, but it comes with significant risks. Implementing and adhering to strict safety protocols, such as lockout/tagout, can prevent injuries and save lives. Employers must ensure that workers are trained, equipment is properly maintained, and safety procedures are followed. With the right precautions, the dangers of hazardous energy can be effectively managed.