Many machines can hurt you even when nobody is touching the controls. A conveyor can start because someone else pressed a button. A press can drop because a valve leaks. A pipe can still hold steam long after the heater is off. Lockout/tagout (LOTO) is the set of rules and practices that stops this from happening while people clean, repair or adjust equipment.
What is hazardous energy?
Hazardous energy is any source of power that can injure a person if it starts, moves or is released unexpectedly. The OSHA standard names these kinds:
- Electrical: power lines, panels, motors, batteries.
- Mechanical: moving parts, belts, gears, blades.
- Hydraulic: pressurized oil or fluid.
- Pneumatic: compressed air or gas.
- Chemical: a reaction or a flammable or toxic product in the lines.
- Thermal: heat or cold, such as hot steam lines.
- Other sources of energy.
Stored energy
Switching a machine off does not always remove its energy. Stored energy, also called residual energy, stays behind. Examples:
- a raised press, lift or load that can fall by gravity;
- a spring under tension;
- a spinning flywheel that keeps turning;
- a capacitor that holds an electrical charge;
- pressure in hydraulic, air or steam lines.
Stored energy must be released, blocked or otherwise made safe before anyone puts their hands into the machine.
The standard
The rule is 29 CFR 1910.147, The control of hazardous energy (lockout/tagout), issued by the U.S. Occupational Safety and Health Administration (OSHA). It covers servicing and maintenance of machines and equipment where unexpected energization or start-up, or the release of stored energy, could injure employees.
Servicing and maintenance includes work such as:
- constructing, installing, setting up and adjusting equipment;
- inspecting, modifying and maintaining it;
- lubricating, cleaning or unjamming it;
- making adjustments or tool changes.
What the standard requires of an employer
The employer must set up an energy control program. It has three parts:
- Energy control procedures, written for the equipment.
- Training for employees.
- Periodic inspections of the procedures, at least once a year.
Before anyone services equipment where unexpected energization could cause injury, the equipment must be isolated from its energy and made inoperative. Locks or tags are then put on the isolating devices.
Where the standard applies
The standard is part of OSHA's general industry rules (29 CFR Part 1910). It does not cover:
- construction work and agriculture;
- shipyards, marine terminals and longshoring, which have their own parts of the rules;
- electric utility power generation, transmission and distribution;
- electrical hazards from installations covered by Subpart S (see lesson 7);
- oil and gas well drilling and servicing.
Some of these have other hazardous-energy rules of their own. A worker in one of these jobs should ask the employer which rule applies.
Federal and state rules
OSHA runs the program directly in some states. About half of the states run their own OSHA-approved state plans. State plans must be at least as effective as the federal rules, and some are stricter. State plans also cover state and local government workers, whom federal OSHA does not cover.
What to remember
- Hazardous energy includes electrical, mechanical, hydraulic, pneumatic, chemical and thermal energy.
- Stored energy can hurt you after the power is off.
- 29 CFR 1910.147 covers servicing and maintenance in general industry.
- The employer must have procedures, training and inspections.
- Ask your employer which rules apply in your state and job.