A maintenance tech is about to clear a jam in a roller. The machine is switched off at the panel. Is that enough? Under OSHA's energy control standard, almost never — and the gap between "switched off" and "locked out" is where serious machine injuries happen.
Read this as an orientation, not as a compliance document. 29 CFR 1910.147 is legally consequential, and a compliant energy control program is the employer's responsibility. Nothing here replaces the text of the standard, your own written procedures, or advice from a qualified safety professional. What follows is a plain-language map of the standard, so you know what you are buying lockout / tagout hardware to support.
What the standard is for, and where it applies
1910.147 covers "servicing and maintenance of machines and equipment in which the unexpected energization or start up of the machines or equipment, or release of stored energy could cause injury." Servicing and maintenance is defined broadly — constructing, installing, setting up, adjusting, inspecting and modifying — so it reaches well beyond obvious repair work.
It does not cover everything. Construction, agriculture, maritime employment, electric utility generation and distribution installations, electrical hazards covered by Subpart S, and oil and gas well drilling all sit outside it. There is also a narrow exemption for cord- and plug-connected equipment where unplugging puts the plug under the employee's exclusive control. Where that control is not exclusive, a plug lockout is the usual answer.
The three parts of an energy control program
The standard describes a program, not a box of locks. Under 1910.147(c)(1) it consists of energy control procedures, employee training and periodic inspections. All three must exist; hardware only makes the first one physically possible.
Procedures must be "developed, documented and utilized," and 1910.147(c)(4) requires each to include a statement of its intended use, specific steps for shutting down, isolating, blocking and securing the equipment, steps for placing, removing and transferring devices, and requirements for testing to verify the isolation actually worked. There is a documentation exception, but it applies only when a demanding list of conditions is all true at once — a single readily identifiable energy source, no stored energy hazard, a single lockout device, exclusive employee control, no hazard to others, and no prior accidents.
Lockout versus tagout
| Lockout | Tagout | |
|---|---|---|
| What it is | A device using "a positive means such as a lock, either key or combination type, to hold an energy isolating device in a safe position" | "A prominent warning device, such as a tag and a means of attachment," indicating the device may not be operated |
| Effect | The isolating device and equipment "cannot be operated" | The isolating device and equipment "may not be operated" — a warning, not a physical restraint |
| When it is allowed | Required where the energy isolating device can be locked out | Permitted where the device cannot be locked out; otherwise only if the employer demonstrates equivalent protection |
| Extra burden | None beyond the standard's normal requirements | Attach where a lock would go, plus an additional measure such as removing an isolating circuit element, blocking a controlling switch, opening an extra disconnect, or removing a valve handle |
There is also a hard date: energy isolating devices for machines installed or majorly replaced after 2 January 1990 must be designed to accept a lockout device. Tagout-only is a narrow exception that must be justified, and the standard's training requirements dwell on the limits of tags — warning devices only, never to be removed without authorisation, and capable of creating a false sense of security.
Authorized, affected and other employees
The standard defines three populations, each with different training.
- Authorized employees lock or tag out equipment in order to service it. They are trained on recognising hazardous energy sources, the type and magnitude of energy present, and the means of isolating and controlling it. Only they may apply lockout or tagout: 1910.147(c)(8) says it is "performed only by the authorized employees who are performing the servicing or maintenance."
- Affected employees operate or use the machine being serviced. They are instructed in the purpose and use of the procedure, and must be notified before controls are applied and after removal.
- Other employees, meaning anyone whose work is in the area, are instructed about the procedure and about the prohibition on attempting to restart or re-energize anything locked or tagged out.
Retraining is required on a change of job assignment, a change in machines or processes presenting a new hazard, a change in procedures, or whenever a periodic inspection reveals gaps in an employee's knowledge. Training must be certified, with each employee's name and training dates.
The sequence
- Prepare. The authorized employee determines the type and magnitude of the energy, its hazards and the means of control.
- Shut down. Using the established procedure, in an orderly way that creates no additional hazards.
- Isolate. Operate every energy isolating device needed to separate the machine from its energy sources — all of them, not just the main disconnect.
- Apply devices. Authorized employees affix devices to each isolating device, holding it in the safe or off position.
- Release stored energy. After devices are applied, all potentially hazardous stored or residual energy is "relieved, disconnected, restrained, and otherwise rendered safe."
- Verify. Before work starts, the authorized employee verifies that isolation and de-energization were actually achieved.
Release runs in reverse: inspect the work area, check that everyone is clear, notify affected employees, and remove each device. Critically, "each lockout or tagout device shall be removed from each energy isolating device by the employee who applied the device." The narrow exception for an unavailable employee requires a documented procedure and reasonable attempts at contact.
Hardware requirements
1910.147(c)(5) is unusually specific. Devices must be provided by the employer, must be singularly identified, must be the only devices used for energy control, and must not be used for anything else. They must also be:
- Durable — able to withstand the environment for the maximum expected exposure, including weather, damp and corrosive conditions.
- Standardized within the facility by colour, shape or size; tagout devices also by print and format. Hence the consistent red of safety padlocks.
- Substantial — lockout devices must resist removal without excessive force or cutting tools, and tag attachments must have a minimum unlocking strength of no less than 50 pounds.
- Identifiable — the device "shall indicate the identity of the employee applying" it.
That last pair is worth thinking through before ordering. A personal lockout kit assigned to one named tech maps naturally onto "singularly identified" and "identifiable." A keyed-alike padlock set is convenient where one authorized employee applies several locks in a single procedure, but how keying is assigned across your workforce is a decision to make deliberately with your safety lead against those requirements. Where one isolating device needs more than one lock, a lockout hasp is the usual answer, and a breaker takes a device sized to it, such as an oversized clamp-on breaker lockout.
Group lockout
When a crew or department services equipment together, 1910.147(f)(3) requires a procedure giving each employee protection equivalent to a personal lock. Primary responsibility rests with an authorized employee for a defined set of workers; that person must be able to ascertain the exposure status of individual group members; where multiple crews are involved, one authorized employee coordinates overall. The mechanism is simple: "Each authorized employee shall affix a personal lockout or tagout device to the group lockout device, group lockbox, or comparable mechanism when he or she begins work, and shall remove those devices when he or she stops working." A group lock box is the physical implementation of that sentence.
Periodic inspection
This is the requirement most often missed. Under 1910.147(c)(6) the employer must inspect the energy control procedure at least annually, and it must be "performed by an authorized employee other than the one(s) utilizing the energy control procedure being inspected." It must correct any deviations or inadequacies found. For lockout it includes a review between the inspector and each authorized employee of that employee's responsibilities; for tagout it extends to affected employees too.
The employer must then certify it, identifying the machine or equipment, the date, the employees included and the person who performed it. An annual inspection that leaves no record behind will not survive scrutiny.
Again: this article is educational. Build your program from the standard itself and qualified advice, then buy hardware to fit it — not the other way round.
This guide is educational. Selection and compliance remain the employer's responsibility under the applicable standard.