Lockout/Tagout Device Requirements Under OSHA 1910.147(c)(5): Durable, Standardized, Substantial, Identifiable
Most energy control audits look at procedures, training, and periodic inspections. The devices themselves get a glance. That is a mistake, because the hardware is where the standard gets specific, and it is where a cheap padlock or a string-tied tag quietly undoes an otherwise solid program. A lock that pops off with a screwdriver protects no one. OSHA knew that, so it wrote four device rules into the standard and one very exact number for tags.
This guide walks through what 29 CFR 1910.147(c)(5) requires of your locks and tags, why the substantiality rule reads differently for a lock than for a tag, what the 50-pound nylon cable tie standard actually means, and the hardware gaps we find most often in the field.
The Employer Provides the Devices
Before the four rules, one sentence sets the baseline. Under 1910.147(c)(5)(i), locks, tags, chains, wedges, key blocks, adapter pins, self-locking fasteners, and other hardware for isolating, securing, or blocking machines from their energy sources shall be provided by the employer. The worker does not bring their own lock from the toolbox. The company supplies devices that are dedicated to energy control and used for nothing else.
That last part matters. Lockout devices have to be used only for controlling energy, not for hanging a coat or securing a gate. Mixing purposes is how a lockout padlock ends up on a locker and a locker padlock ends up on a disconnect, and the moment your locks are interchangeable with ordinary hardware, the standardization and identification rules below start to fall apart.
Rule One: Durable
A device is durable when it withstands the environment it lives in for the maximum period of time it is expected to be in place. A lock hanging on an outdoor disconnect at a foundry sees heat, moisture, and grit. A tag in a food plant washdown zone sees water, caustic cleaners, and daily hosing. The standard is explicit that tagout devices must be constructed and printed so that weather, wet or damp locations, and corrosive environments such as acid and alkali areas will not cause the tag to deteriorate or the message to become illegible.
The practical test is simple. If the environment would fade the print, rust the metal, or rot the attachment before the job is done, the device is not durable enough for that location. This is exactly the kind of point-of-use detail that surfaces during a food and beverage sanitation LOTO program, where a paper tag that looks fine on Monday is unreadable pulp by Friday.
Rule Two: Standardized
Lockout and tagout devices must be standardized within the facility in at least one of three criteria: color, shape, or size. Tagout devices carry one more: they must also be standardized in print and format. The intent is instant recognition. Anyone who walks up to an isolated machine should see a lock or a tag and know without a second thought that it is a lockout device, not a maintenance marker, a quality-hold tag, or a lock somebody bought at the hardware store.
Standardization usually means the facility buys one line of red safety padlocks and one format of danger tag, and those are the only lockout devices in the building. Color is the most common choice because it reads from across an aisle. When a plant has three colors of padlock in use and no rule about which is which, an inspector does not have to guess whether the program is controlled. The floor already answered.
Rule Three: Substantial (and Why It Splits)
Substantiality is the rule people misquote, because it means two different things depending on whether you are holding a lock or a tag.
Lockout devices
A lockout device must be substantial enough to prevent removal without excessive force or unusual techniques, such as with bolt cutters or other metal cutting tools. In plain terms, you should not be able to pry it, twist it, shim it, or pop it off by hand or with a common tool. Getting it off should require deliberate destruction. A lightweight luggage lock or a worn padlock with a loose shackle fails, because the whole promise of a lock, that the machine stays isolated until the owner removes it, depends on the lock actually holding.
Tagout devices
A tag cannot physically prevent anything, so the standard aims its substantiality rule at accidental removal instead. A tagout device and its means of attachment must be substantial enough to prevent inadvertent or accidental removal. Then comes the one hard number in this entire section. The attachment must be a non-reusable type, attachable by hand, self-locking, and non-releasable with a minimum unlocking strength of no less than 50 pounds, with the general design and basic characteristics of at least a one-piece, all-environment-tolerant nylon cable tie.
Read that as a ban as much as a spec. String, cord, wire twists, and adhesive-backed tags are out. They are reusable, they release too easily, and they fail the 50-pound test. The tag has to attach like a heavy-duty zip tie that you cannot slip off without cutting it. If your tags hang from a loop of string, you have a finding, and it is a common one.
| Attribute | Lockout device | Tagout device |
|---|---|---|
| Durable | Survives the environment for the full job | Print and material survive weather, wet, and corrosive areas |
| Standardized | Color, shape, or size | Color, shape, or size, plus print and format |
| Substantial | No removal without excessive force or metal-cutting tools | 50-pound minimum, non-reusable, self-locking, nylon-cable-tie equivalent |
| Identifiable | Indicates the employee who applied it | Indicates the employee who applied it |
Rule Four: Identifiable
Lockout and tagout devices must indicate the identity of the employee who applied them. This is the accountability rule, and it is the one that ties the hardware back to the human. A lock with no name is a lock nobody owns, which means nobody can say whether the isolation is still needed or who has the authority to take it off. Labeled locks, engraved tags, and photo tags all satisfy it. A drawer of identical unlabeled padlocks does not.
Identification is also what makes the harder situations governable. When an authorized employee is absent and their lock has to come off, the whole procedure starts with knowing whose lock it is. And on crew work, personal identification on every device is what keeps a group lockout honest. Anonymous hardware quietly erases the chain of custody the rest of the standard depends on.
Tagout Legends: The Warning Itself
1910.147(c)(5)(iii) adds a content requirement that applies only to tags. A tagout device must warn against hazardous conditions if the machine or equipment is energized and must include a legend such as Do Not Start, Do Not Open, Do Not Close, Do Not Energize, or Do Not Operate. The warning has to be legible and understandable to all affected employees, which in a mixed-language workforce can mean bilingual tags or clear symbols alongside the text.
This is more than a formality. A tagout-only system leans entirely on that message, because there is no lock backing it up. That is one reason tagout-only programs must clear a higher bar overall, a subject we cover in full in our guide to tagout-only systems under 1910.147. The tag is the whole safeguard, so the tag has to say the right thing, clearly, and stay attached to say it.
Where Programs Fall Short on Hardware
The device rules are short, which is exactly why they get skimmed. The failures we see in the field cluster into a handful of patterns.
- Personal padlocks from home. A worker uses their own lock because the shop ran out. It is not employer-provided, not standardized, and often not identifiable.
- String-tied or adhesive tags. The single most common tagout finding, and a direct miss on the 50-pound attachment rule.
- Unlabeled locks. A bin of identical brass padlocks with no names. Fine until two crews and a contractor are on the same line and no one can read the isolation.
- Mixed colors with no meaning. Red, black, and blue locks in circulation with no written convention, so standardization exists on paper but not in practice.
- Faded outdoor tags. Tags rated for indoor use hung on outdoor or washdown equipment, illegible within weeks.
None of these are exotic. Each one is a device that looks close enough to right that it survives a casual walkthrough, and each one is a citation an inspector can write in the time it takes to point at it. Device selection is not a purchasing footnote. It is the physical layer the entire energy control procedure rests on, which is why we treat it as a checklist item on every machine-specific energy control procedure and every program review. OSHA's own lockout/tagout eTool on materials and hardware lays out the same device criteria in checklist form.
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Request Your AssessmentFrequently Asked Questions
What does OSHA 1910.147(c)(5) require of lockout and tagout devices?
It requires that the employer provide the devices and that every lockout and tagout device be durable, standardized, substantial, and identifiable. Durable means it survives the environment. Standardized means locks and tags look alike across the facility. Substantial means it resists removal. Identifiable means it names the employee who applied it.
How strong does a tagout device attachment have to be?
The attachment must be non-reusable, attachable by hand, self-locking, and non-releasable with a minimum unlocking strength of no less than 50 pounds, with the general design and basic characteristics of at least a one-piece, all-environment-tolerant nylon cable tie. String, cord, and adhesive tags do not meet the rule because they come off too easily.
What does standardized mean under 1910.147(c)(5)?
Lockout and tagout devices must be standardized within the facility in at least one of three ways: color, shape, or size. Tagout devices carry an added requirement to be standardized in print and format. The point is that a lock or tag is instantly recognized as a lockout device and not confused with any other hardware on the floor.
How substantial does a lockout device have to be?
A lockout device has to be substantial enough that it cannot be removed without excessive force or unusual techniques, such as bolt cutters or other metal-cutting tools. A padlock that can be pried, twisted, or shimmed off by hand fails the rule. The lock has to genuinely hold the isolating device in the safe position.
Does the tag or lock have to name the worker who applied it?
Yes. Lockout and tagout devices must indicate the identity of the employee applying them. In practice that means labeled locks, engraved or photo tags, or a tag line naming the authorized employee. Anonymous hardware breaks accountability, because no one can tell whose isolation it is or who has the authority to remove it.
Can a tagout device be a plain tag with any wording?
No. Tagout devices must warn against hazardous conditions if the machine is energized and must carry a legend such as Do Not Start, Do Not Open, Do Not Close, Do Not Energize, or Do Not Operate. The warning has to be legible and understandable to all employees, and the tag has to withstand the environment where it hangs.