What Is Hazardous Energy? Identifying Energy Sources and How to Control Them

Key Takeaways

• Hazardous energy is any energy that can injure a worker through unexpected energization, startup, or release while machinery or equipment is being serviced or maintained.

• Common forms include electrical, mechanical, hydraulic, pneumatic, chemical, thermal, gravitational, and radiation energy. Several of these forms can remain stored after equipment is shut down.

• Workers may be exposed during tasks such as setup, adjustment, cleaning, inspection, unjamming, troubleshooting, repair, and other servicing activities.

• OSHA’s lockout/tagout standard establishes the legal baseline for covered servicing work. ANSI B11 standards may provide supplementary risk-assessment guidance, but they do not replace OSHA requirements.

What Is Hazardous Energy?

Hazardous energy is energy that can injure workers if machinery or equipment unexpectedly starts, becomes energized, or releases stored energy during servicing or maintenance. It can be electrical, mechanical, hydraulic, pneumatic, chemical, thermal, gravitational, radiation, or another form capable of causing harm.

Energy may be actively moving through a system or remain stored after the equipment is shut down. Pressure in a hydraulic line, tension in a spring, charge in a capacitor, heat in a pipe, or the weight of an elevated component can still expose a worker until that energy is released, restrained, blocked, or otherwise controlled.

When Can Workers Be Exposed to Hazardous Energy?

Workers can be exposed when servicing or maintenance places them near a machine’s point of operation, energy-isolating devices, moving parts, pressurized systems, elevated components, or other danger zones. Common exposure situations include setup, adjustment, inspection, cleaning, unjamming, tool changes, troubleshooting, and repair, especially when a guard is removed or bypassed or part of the body enters an area where work is performed.

The key issue is not the task name alone. OSHA’s lockout/tagout standard applies when unexpected energization, startup, or the release of stored energy during covered servicing or maintenance could injure an employee, subject to the standard’s scope and limited exceptions.

To effectively apply control of hazardous energy, it’s necessary to distinguish between hazardous, non-hazardous, and beneficial energy. According to ANSI B11.0-2023, Safety of Machinery:

• Hazardous energy is any energy that poses a risk of injury during a task.
• Non-hazardous energy is energy that does not expose personnel to harm during a task. For example, a low-voltage circuit used for diagnostics might be considered non-hazardous if it does not present an electrical shock or arc risk.
• Beneficial energy is energy required to reduce risk. It may be necessary to complete a task safely, such as maintaining control of coil tension or powering a Human Machine Interface (HMI) for troubleshooting.

Energy classification depends on the context of the task. As ANSI notes, energy considered non-hazardous in one situation may be hazardous in another. This task-specific view is the foundation of modern risk-based approaches like Task-Based Risk Assessment (TaBRA), which evaluates both the task and the energy involved before deciding on control measures.

Types of Hazardous Energy

Hazardous energy is commonly grouped into electrical, mechanical, pneumatic, hydraulic, gravitational, thermal, chemical, and radiation forms. Some sources combine or separate these categories, so there is no single universal count. The practical question is which energy sources are present during the task, how they could reach a worker, and what energy could remain stored or build up again after shutdown.

Type of Hazardous Energy	Definition	Examples
Electrical Energy	Energy associated with electric charge in circuits, wiring, batteries, capacitors, and electrical equipment.	Live conductors, energized panels, batteries, and capacitors that retain a charge after power is disconnected.
Mechanical Energy	Kinetic or potential energy in moving or mechanically loaded components.	Rotating flywheels, coasting parts, compressed or tensioned springs, conveyors, and components that can shift or move.
Pneumatic Energy	Energy stored in compressed air or gases used in actuators, tools, or systems.	Air compressors, pneumatic cylinders, or air brakes in manufacturing equipment.
Hydraulic Energy	Energy stored in pressurized liquids used in systems like lifts, jacks, or presses.	Hydraulic presses, vehicle lift systems, or heavy equipment using hydraulic fluid.
Gravitational Energy	Potential energy in an elevated or unsupported component or load that can fall or move downward.	Raised machine parts, suspended loads, lift platforms, and equipment that must be blocked against movement.
Thermal Energy	Heat energy present in systems operating at high temperatures such as boilers or steam lines.	Steam pipes, furnace systems, or molding machines operating at high heat.
Chemical Energy	Energy stored in chemical bonds, released during reactions involving fuels, batteries, or reactive substances.	Battery systems, fuel storage tanks, or chemical mixing and processing equipment.
Radiation Energy	Energy transmitted as electromagnetic radiation or particles that can harm workers if exposure is not adequately controlled.	UV or laser sources, X-ray equipment, gamma-radiography sources, and neutron or other particle-radiation sources, depending on the process.

Dangers of Hazardous Energy

On August 24, 2022, a fourth-year HVAC apprentice was fatally electrocuted while cleaning a chiller unit at University Academy, a charter school in Kansas City, Missouri. OSHA found that the employer failed to de-energize the equipment and prevent unintentional startup; although the fan motor had been turned off through the building’s HVAC management system, lockout/tagout had not been applied to ensure electrical power was removed. 

This incident illustrates a critical breakdown in basic safety protocols: assuming that equipment is safe to service without physically isolating energy sources. Across industries, uncontrolled hazardous energy continues to result in serious injuries, equipment damage, and operational disruption. The following are some of the most serious consequences of failing to control hazardous energy:

• Severe Physical Injuries: Injuries can range from electrocution, burns (from thermal or chemical energy), to trauma (from mechanical or gravitational energy), such as burns from steam leaks or crushing injuries from a mechanical press.
• Equipment and Property Damage: Improper management of hazardous energy can cause significant damage to machinery and property, such as machinery operating uncontrollably due to a sudden release of hydraulic energy, leading to equipment destruction.

• Fires and Explosions: Hazardous energy, particularly chemical and electrical, can trigger fires or explosions if unexpectedly released, threatening human life, causing property damage, and potentially harming the environment.
• Health Effects: Exposure to radiation or chemicals can lead to long-term issues such as cancer or organ damage. Incidents may also cause psychological effects like anxiety, PTSD, or depression, impacting a worker’s well-being and performance.
• Operational Disruption: Hazardous energy-related incidents can disrupt operations, leading to downtime, loss of production, and financial losses—all of which negatively impact company reputation and worker morale.

OSHA and ANSI Standards for Hazardous Energy Control

OSHA’s 29 CFR 1910.147 establishes minimum requirements for controlling hazardous energy during covered servicing and maintenance in general industry. Other industries and electrical work may be subject to different OSHA standards. Safety professionals may also consult ANSI/ASSP Z244.1-2024, the current consensus standard specifically addressing lockout, tagout, and alternative methods, and ANSI B11.0-2023 for machinery risk assessment. These voluntary consensus standards can supplement an OSHA-compliant program, but they do not replace or narrow applicable OSHA requirements.

The table below highlights key differences between OSHA’s compliance-driven requirements and ANSI’s performance-based recommendations:

While ANSI offers expanded flexibility for managing hazardous energy, OSHA’s standard remains the baseline legal requirement. Organizations must meet all OSHA requirements even when applying ANSI-aligned practices. The key components of the OSHA standard include:

• Energy Control Procedures: Employers must develop, document, and utilize hazardous energy control procedures for affixing appropriate lockout or tagout devices to energy-isolating devices, and to otherwise disable machines or equipment to prevent unexpected energization, startup, or release of stored energy.
• Employee Training: This involves instructing workers on the specific procedures and restrictions related to energy control measures relevant to their job assignments.
• Inspection: OSHA requires that periodic inspections of the energy control procedures be conducted at least annually to ensure that the procedures and the requirements of the standard are being followed.
• Energy Isolation: Clear identification and proper isolation of all relevant energy sources for machines or equipment involved in maintenance or servicing are crucial.
• Lockout/Tagout Devices: These LOTO devices must be durable, standardized, and substantial enough to prevent removal without excessive force or unusual techniques. Tagout devices must clearly indicate the identity of the employee applying the device.

Developing a Hazardous Energy Control Program

A well-built hazardous energy control program provides a structured system for identifying energy sources, defining control procedures, and assigning responsibilities during maintenance and servicing. The program serves as both a compliance framework and a practical tool for daily operations. Its effectiveness depends on clarity, consistency, and how well it's integrated into existing workflows.

Some safety programs fail because they are treated as separate from operations. Mike Taubitz, whose safety career spans more than 40 years and includes serving as General Motors’ global director of safety and ergonomics and membership on the ANSI B11 and Z244.1 standards committees, argues that safety and operational performance should be designed together: ‘Companies do not have to “balance” safety and operational efficiency. When productivity and quality improve, so does safety.

He further illustrates this by describing a scenario where equipment runs flawlessly with no unplanned maintenance or breakdowns. In that environment, there’s little need for workers to bypass safeguards or enter hazardous zones to restore production. Fewer disruptions mean fewer chances for exposure to uncontrolled hazardous energy.

This concept emphasizes that efficient operations and effective energy control go hand in hand. When systems are predictable, maintained, and stable, both safety and output improve together—not at each other’s expense.

The value of structured programs is also reflected in national data. According to OSHA, proper implementation of lockout tagout prevents an estimated 120 fatalities and 50,000 injuries each year. This reinforces that safety systems, when embedded in daily operations, protect both people and performance.

Hazardous Energy Control Policy

A written hazardous energy control policy is the backbone of any energy control program. It sets clear expectations for isolating hazardous energy during servicing, maintenance, and non-routine tasks. This policy must be formal, enforceable, and accessible to all relevant personnel. It must include the following:

Scope of Coverage

Defines which machines, systems, and energy types are included. Must cover all tasks where stored energy or unexpected startup can pose a risk, such as maintenance, cleaning, diagnostics, or setup.

Application Criteria

Specifies when lockout tagout must be applied. This includes specific triggers like opening a guard, entering a danger zone, or bypassing a normal production safeguard.

Roles and Permissions

• Identifies roles: authorized, affected, and other personnel
• Lists who can apply locks and tags, who verifies isolation, and who restores equipment to service
• Prevents miscommunication by making authority levels and responsibilities explicit

Required Procedures:

• Shutdown and Isolation Steps: The policy must outline how to shut down equipment, isolate all energy sources, and control stored energy. Generic guidance is not enough—steps must reflect the actual machines in use.
• Verification Requirements: Before work begins, the authorized employee must verify that the machine or equipment has been isolated and de-energized. The procedure should specify verification methods appropriate to the energy source, such as operating the normal controls after confirming that no personnel are exposed and/or using properly rated test instruments. A visual check alone should not be treated as sufficient where it cannot establish de-energization.
  

The policy should require an inspection of each energy control procedure at least annually, as OSHA specifies. It should also require the applicable procedure and training to be reviewed when an incident, near miss, equipment change, or observed deficiency shows that the existing controls may no longer reflect the work. The annual compliance requirement applies to the periodic inspection of each procedure, not to a generic annual rewrite of the overall policy.

Training requirements should also be embedded in the policy. It should define when training occurs (e.g., initial, refresher, or change of assignment) and what each role must understand. Records of completed training should tie back to the policy as proof of implementation.

A robust hazardous energy control policy connects daily practices to broader safety objectives. When well-written and consistently enforced, it supports regulatory compliance, operational clarity, and worker protection in equal measure.

Control of Hazardous Energy: Roles and Responsibilities

A key element of an effective Hazardous Energy Control Program involves the clear definition of the roles and responsibilities of parties involved in the protocol, particularly the employer, supervisors, and workers.

Employer Responsibilities

Employers are responsible for developing and sustaining the entire hazardous energy control program. This includes writing procedures, selecting appropriate lockout tagout devices, ensuring training is delivered, and allocating time and resources for proper implementation. They must also assign clear authority for who can apply locks, verify isolation, and return equipment to service.

One of the most overlooked aspects of program effectiveness is how risk is identified. Mike Taubitz stresses the value of engaging frontline personnel directly:

“Engage operators, mechanics, and other service personnel using Task-Based Risk Assessment to identify situations where tasks are performed and the energy sources are then identified as hazardous, non-hazardous, or beneficial.”

This approach builds a more accurate and functional program by aligning control strategies with how tasks are actually done—not just how they’re documented. It also improves buy-in, since workers are more likely to follow procedures they helped shape.

Employers must also schedule regular audits and evaluations of the program. That includes reviewing training records, inspecting equipment-specific procedures, and tracking corrective actions after incidents or near-misses. Without these mechanisms, enforcement becomes inconsistent and risks go unaddressed.

Supervisor Responsibilities

The employer may assign supervisors responsibility for monitoring how the energy control program is applied in daily work. Depending on the employer’s written program, that may include confirming that the correct procedure is available, observing work practices, addressing deviations, and escalating conditions that require a procedure or hazard-classification review.

Supervisors should also know the limits of their assigned role. The authorized employee performing the lockout must have the knowledge and skills required to recognize hazardous energy and apply the required controls, while the employer remains responsible for developing, using, and enforcing the overall program.

Worker Responsibilities

Worker responsibilities depend on the employee’s role under the energy control program. Authorized employees are the employees who apply lockout or tagout to perform servicing or maintenance; they must recognize applicable hazardous energy sources, understand the type and magnitude of energy, apply the required isolation and control measures, and verify isolation before work begins. Affected employees operate or use the equipment, or work in the area, and must be instructed in the purpose and use of the energy control procedure. Other employees who may work in the area must understand the procedure and the prohibition against restarting or re-energizing locked or tagged equipment.

All employees should report unclear procedures, unexpected conditions, or equipment problems, but the employer remains responsible for establishing, training on, and enforcing the energy control program.

Hazard Identification, Assessment, and Control

The process of hazard identification, assessment, and control is fundamental to the management of hazardous energy in the workplace. It involves a systematic approach to identifying all sources of hazardous energy, assessing the risks associated with these sources, and implementing appropriate controls to mitigate these risks. 

Hazard Identification
Primarily involves conducting a comprehensive review of all equipment, machinery, and processes within the organization and understanding how equipment operates, the types of energy involved, and any potential sources of hazardous energy. For a more complete picture, this process also includes a review of previous incidents, near-misses, and maintenance records, as well as gathering valuable insights from employees.

Risk Assessment
Risk assessment evaluates exposure to all relevant hazardous-energy scenarios, including unexpected energization or startup and the release or reaccumulation of stored energy. It should consider the type and magnitude of energy, how a worker could be exposed, the severity of potential harm, and the effectiveness and failure modes of existing controls.

Control Implementation
For servicing covered by 29 CFR 1910.147, the primary control is energy isolation: shut down the machine, isolate applicable energy sources, apply lockout or permitted tagout, render stored or residual energy safe, and verify isolation before work begins. Engineering controls, administrative controls, and PPE may supplement protection or apply under another standard or a specific exception, but they do not generally replace required energy isolation.

Lockout Tagout and Control of Hazardous Energy

The Lockout Tagout (LOTO) procedure is a critical safety protocol aimed at preventing the accidental release of hazardous energy while equipment is being serviced or maintained. Effective LOTO procedures control hazardous energy and protect employees by ensuring that machines are properly shut down and cannot be restarted until the completion of maintenance or repair work. 

Lockout/tagout generally involves preparing for shutdown, shutting down the machine, isolating each applicable energy source, applying lockout or tagout devices, relieving or restraining stored energy, and verifying isolation before work begins. After servicing is complete, the authorized employee follows the employer’s procedure for inspecting the work area, removing devices, notifying affected employees, and restoring the equipment to service.

For the complete sequence, verification requirements, and restoration steps, see our lockout tagout procedure guide.

As a general rule, each lockout or tagout device must be removed by the employee who applied it. If that employee is unavailable, the employer may direct removal only under a specific procedure and training program that provides equivalent safety, including verification that the employee is not at the facility, reasonable efforts to contact the employee, and confirmation that the employee knows about the removal before resuming work.

Lockout Tagout Devices

Lockout/tagout hardware must be selected for the machine’s actual energy-isolating devices and the conditions in which it will be used. OSHA requires lockout and tagout devices to be durable, standardized, substantial, identifiable, and used only for controlling energy. Common options include lockout padlocks, hasps, valve and breaker lockouts, plug and cable lockouts, group lock boxes, and tags.

The equipment-specific energy control procedure should identify the isolation points and the devices needed at each one. For selection guidance and examples, see our types of lockout tagout devices.

Hazardous Energy Control Documentation

The last key component of an effective Hazardous Energy Control Program revolves around the extensive documentation of safety measures and procedures. This is critical to ensuring compliance with regulatory standards, facilitating training, and enhancing safety through transparency and accountability.

Energy Control Procedures

Each set of procedures should be tailored to specific types of equipment and operations. This includes step-by-step shutdown and restart procedures, identifying the appropriate lockout/tagout devices, and specifying the exact isolation points for each energy source. Ensure these documents are easily accessible to all relevant personnel. 

Training Records

OSHA requires employers to certify that employee training has been completed and kept current. The certification must include each employee’s name and the date of training. Employers may also retain the curriculum, delivery method, instructor, and role-specific content as useful program records, but LOTO training does not have a universal expiration date or fixed refresher schedule. Retraining is required when the triggers in 29 CFR 1910.147(c)(7)(iii) apply.

Inspection Reports

Document OSHA’s periodic inspection of each energy control procedure at least annually. The inspection must be performed by an authorized employee other than the employee or employees using the procedure being inspected. The employer must certify the machine or equipment involved, the inspection date, the employees included, and the person performing the inspection, and any identified deviations or procedural inadequacies must be corrected.

Incident Reports

Encourage and train employees to report incidents and near-misses immediately. Quick documentation ensures that details are accurate and that the response can be initiated promptly. Each report should include a thorough analysis to determine the root cause of the incident to aid in developing effective preventive and corrective actions.

Audit Records

Audits should result in detailed findings that are formally recorded. This includes any non-compliances, suggestions for improvement, and commendations for areas well managed. Document whether audits are conducted by internal staff or external experts. Each type offers different benefits and insights.

 

Alternative Energy Control Methods and Their Limits

Lockout/tagout remains the required method for covered servicing and maintenance unless the work falls within a specific exception or another standard applies. The fact that lockout is inconvenient, slows production, or prevents a diagnostic task does not by itself permit an alternative method.

One limited exception applies to minor servicing performed during normal production operations when the work is routine, repetitive, and integral to production and the employer uses alternative measures that provide effective protection. Other exclusions and special provisions have their own conditions. The employer should confirm which OSHA requirement applies before using a task-based alternative.

ANSI B11 standards can help qualified teams assess machinery risks and design supplementary risk-reduction measures. They do not create an exception to OSHA or allow an employer to replace required lockout solely because another method appears practical.

Task-Based Risk Assessment (TaBRA)

Task-Based Risk Assessment (TaBRA) is a method used to evaluate hazardous energy risk based on the task being performed, not just the equipment or system involved. It aligns with ANSI B11.0-2023, which requires identifying tasks and hazards as part of the overall risk assessment process. 

TaBRA can support a documented task-based risk assessment, but it does not itself authorize an alternative to OSHA-required lockout/tagout. Under 29 CFR 1910.147, work may proceed with energy present only where a specific exception or provision applies, such as the minor-servicing exception during normal production or temporary re-energization for testing or positioning.

Why Task-First Matters

ANSI B11.0, Clause 6.3, requires that reasonably foreseeable tasks and their associated hazards be identified. This includes normal operations, abnormal conditions, and failure scenarios. Without defining the task first, it’s impossible to accurately classify the energy or apply appropriate controls.

The same energy source can be hazardous during one task and non-hazardous or beneficial during another. For example, power may be needed for a control interface during diagnostics, but would be hazardous during mechanical repairs. TaBRA makes these distinctions task-specific.

Risk Is Not Binary

ANSI B11.0 explicitly states that “zero risk does not exist and cannot be attained.” The goal is to reduce risk to an acceptable level through feasible and practical measures. That level must be determined based on the combination of probability and severity of harm, not assumptions or blanket procedures.

The TaBRA Process

1. Define the task: Document what is being done, how, and under what conditions.
2. Identify energy sources: For each step, determine what energy is present and whether it poses harm during that specific task.
3. Classify energy types: Label energy as hazardous, non-hazardous, or beneficial based on the actual exposure and role in the task.
4. Assess the risk: Use a defined matrix (such as ANSI’s 4x4 model) to determine the risk level for each hazard.
5. Apply feasible controls: Select risk reduction measures appropriate to the task, prioritizing those that are both effective and practicable.

Making Confident Decisions

Deciding whether a control method is sufficient can be a challenge, especially when departing from standard LOTO procedures. TaBRA helps teams make that decision based on documented task steps, actual exposure, and structured evaluation.

As Taubitz notes, “Following this methodology will provide teams with the competence and confidence to stand behind their determination of feasible risk mitigation.” That confidence comes from knowing the process is repeatable, practical, and based on how the work is actually done—not assumptions or guesswork.

Hazard Control Hierarchy

The hazard control hierarchy, as defined in ANSI B11.0, ranks methods of reducing exposure to hazardous energy. It guides teams to apply the most effective controls first, starting at the source of the hazard, rather than relying only on training or personal protective equipment.

Control Methods (in order of preference):

• Elimination: Remove the hazard entirely so it no longer exists during the task. Example: Using automated systems to avoid human entry into danger zones.
• Substitution: Replace the hazard with something less dangerous. Example: Using low-voltage tools instead of live high-voltage panels.
• Engineering Controls: Apply physical barriers or design changes to prevent exposure. Examples: Installing interlocks, fixed guards, or enclosed systems.
• Awareness Aids: Use signals or visuals to alert personnel to hazards. Examples: Warning lights, signage, or system status indicators.
• Administrative Controls: Reduce risk through procedures, scheduling, or training. Examples: Task-specific protocols and trained personnel requirements.
• Personal Protective Equipment (PPE): Provide equipment to reduce the severity of exposure. Examples: Arc-rated suits, gloves, or face shields.

Higher-tier controls offer stronger protection because they reduce reliance on behavior. Lower-tier controls require human action and are more likely to fail under pressure or distraction.

Not every risk control is feasible in every situation. As Taubitz explains, determining whether a risk reduction measure is practicable involves evaluating multiple factors:

• Regulatory obligations
• Introduction of new hazards
• Effectiveness
• Machine performance
• Usability
• Productivity
• Durability and maintainability
• Ergonomic impact
• Economic and technological feasibility

These considerations help teams apply the hierarchy in real settings—prioritizing the best available control while staying grounded in what the task and equipment truly require.

Control Reliability for Alternative Methods

When using alternative methods to control hazardous energy, the safeguards in place must meet a higher standard of reliability. This is especially important when energy is intentionally present during servicing or troubleshooting. In these cases, equipment design and safety systems must compensate for the absence of full isolation.

ANSI B11.0 defines control reliability as the ability of a safety-related control system to perform its intended function under fault conditions. This includes the detection of faults and ensuring that the system moves to a safe state. The purpose is to maintain protection even if part of the control system fails.

After the risk assessment identifies an appropriate risk-reduction measure, ANSI B11.19 provides guidance on implementing safeguarding and other risk-reduction measures. It does not determine which measure is required for a particular task; that selection is addressed through ANSI B11.0 or an applicable machine-specific standard. Any ANSI-based design decision must still be checked against applicable OSHA requirements.

Alternative methods may require control reliability or another defined level of safety-system performance, depending on the selected standard and application. Control reliability is not the same as general system reliability. It focuses on failure detection and response specifically for safety functions. For example, if a safety circuit fails, it must not allow unintended movement or re-energization of a hazardous system.

To meet this requirement, alternative methods often rely on a combination of components such as dual-channel safety circuits, monitoring relays, and fault-tolerant logic systems. These are typically validated through risk assessments and functional safety standards like ANSI B11.26-2024, Functional Safety: General Principles for Designing Safety-Related Parts of Control Systems for Machinery, ISO 13849, or IEC 62061. The safety-related parts must perform consistently, even during foreseeable hardware or software failures.

Where a lawful alternative protective measure relies on a safety-related control system, its required performance must be determined and validated under the applicable standard and risk assessment. Control reliability can support that safety function, but it does not create an OSHA exception or authorize replacement of required lockout/tagout. If 29 CFR 1910.147 applies and no specific exception or provision permits the task to proceed with energy present, energy isolation remains required.

Implementing Alternative Methods in Practice

Once alternative methods are selected through task-based assessment, their success depends on how they are applied. 

Alternative methods require more than an informal judgment that a task is easier with power available. The employer must first determine which OSHA provisions apply, document the task and exposure, select safeguards through the appropriate risk-assessment process, and validate that the resulting method provides the required protection. Qualified engineering and safety personnel should review safety-related control systems and any applicable machine-specific, functional-safety, or consensus-standard requirements.

Taubitz’s task-based perspective is useful because it begins with how work is actually performed. That practical view should support a documented compliance and risk-reduction decision, not replace one.

FAQs

What is hazardous energy?

Hazardous energy is energy that can injure a worker if machinery or equipment unexpectedly starts, becomes energized, or releases stored energy during servicing or maintenance. It can include electrical, mechanical, hydraulic, pneumatic, chemical, thermal, gravitational, radiation, or other energy. The hazard depends on the task, the possible exposure, and how the energy could move, build up, or be released.

When are workers likely to be exposed to hazardous energy?

Exposure commonly occurs during setup, adjustment, cleaning, unjamming, inspection, troubleshooting, repair, and other servicing or maintenance activities. Risk increases when a guard is removed or bypassed, part of the body enters a danger zone, or stored energy remains after shutdown. OSHA’s lockout/tagout standard applies when unexpected energization, startup, or stored-energy release during covered work could cause injury, subject to its scope and limited exceptions.

How many types of hazardous energy are there?

There is no single universal count because safety resources group energy forms differently. A practical workplace review may consider electrical, mechanical, hydraulic, pneumatic, chemical, thermal, gravitational, radiation, and any other energy capable of causing harm. The complete list for a task must come from the equipment, process, and possible exposure rather than a memorized number.

What is stored or residual energy?

Stored or residual energy remains in a machine or system after its primary energy supply has been shut off or isolated. Examples include pressure in hydraulic or pneumatic lines, charge in capacitors, tension in springs, rotating flywheels, retained heat, and elevated components. It must be relieved, disconnected, restrained, blocked, or otherwise rendered safe before covered servicing begins.

What energy is not considered hazardous?

Energy is not automatically non-hazardous because it is low voltage, normally present, or useful to a process. Its classification depends on the task, energy magnitude, possible exposure, and ability to cause injury. Any decision to leave energy present must comply with the applicable OSHA requirements and the employer’s documented risk-control process.