Safety guide · Safety management
Safety signs and signage: colour and shape codes, OSHA classes and how to audit them
Short answer
Safety signs tell a person about a hazard or an instruction through colour, shape and a few words, so it is understood at a glance. In the United States, OSHA 29 CFR 1910.145 sets three classes of sign, danger, caution and safety instruction, each with its own colours, and 29 CFR 1910.144 sets red and yellow as safety colours; ISO 7010 uses a separate system in which the shape and colour show whether a sign prohibits, requires, warns or shows a safe condition.
Under OSHA, a danger sign is red and warns of immediate danger, a caution sign has a yellow background and warns of potential hazards or unsafe practices, and a safety instruction sign has a white background with a green panel and gives general safety instructions: 29 CFR 1910.145(c) and (d). Exit signs must read Exit, be distinctive in colour and have letters at least six inches high, 1910.37(b). ISO 7010, used in many countries and by plants that ship or work internationally, groups signs by shape and colour: red circle with a bar prohibits, blue circle requires an action, yellow triangle warns, green square marks a safe condition and a red square marks fire equipment. Pick one system for the site, train people on what each means and audit the signs. Check your local rules: the legal requirement depends on where you work.
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What are safety signs, and what do they cover?
A safety sign is a surface prepared to warn of a hazard or give a safety instruction to workers or the public who may be exposed to it. 29 CFR 1910.145(a)(1) says the specifications cover the design, application and use of signs intended to indicate and define specific hazards, where failing to mark them may lead to injury or property damage. They cover all safety signs except those for streets, highways and railroads.
Two things are outside the section. It does not apply to plant bulletin boards or to safety posters, 1910.145(a)(1) and (b). A poster about lifting technique is education, not a sign. Second, all new signs and replacements of old signs must follow the specifications, 1910.145(a)(2). That is why a plant that replaces signs one by one ends up with a mix of old and new designs unless someone owns the standard.
In this guide, signage means the whole set of signs on a site, and a sign means one of them. The word tag is different. A tag is a temporary warning hung on a piece of equipment, such as a danger tag on a machine that is out of service, and 1910.145(f) has its own rules for tags.
OSHA sign classes and colours: danger, caution, safety instruction
29 CFR 1910.145(c) classifies signs by use. The table gives each class, its colours and when to use it, with the paragraph for each.
| Class | Colours | Use it for | Paragraph |
|---|---|---|---|
| Danger | Red, black and white; danger signs are painted red | Immediate danger, where special precautions are necessary | 1910.145(c)(1) and (d)(2); 1910.144(a)(1)(ii) |
| Caution | Yellow background; panel black with yellow letters, or letters black on the yellow background | Potential hazards, or cautions against unsafe practices | 1910.145(c)(2) and (d)(4) |
| Safety instruction | White background; panel green with white letters, or letters black on the white background | General instructions and suggestions on safety measures | 1910.145(c)(3) and (d)(6) |
The colours are those of opaque glossy samples in the tables of ANSI Z53.1-1967 or ANSI Z535.1-2006(R2011), which 1910.145(d) incorporates by reference. Order signs from a supplier that states which it meets.
Employees must be instructed that danger signs indicate immediate danger and that special precautions are necessary, 1910.145(c)(1)(ii), and that caution signs indicate a possible hazard against which proper precaution should be taken, 1910.145(c)(2)(ii). There is to be no variation in the type of design of signs that warn of specific dangers and radiation hazards, 1910.145(c)(1)(i). Keep danger for what is truly dangerous. A plant that puts danger on everything teaches people to read none of it.
Tags follow the same ladder. Danger tags are for major hazard situations where an immediate hazard threatens death or serious injury, 1910.145(f)(5). Caution tags are for minor hazards where a non-immediate or potential hazard presents a lesser threat, 1910.145(f)(6). A warning tag may be used for a hazard level between caution and danger, 1910.145(f)(7). Appendix A to 1910.145(f) recommends red for danger, yellow for caution and orange for warning, but says the standard does not mandate tag colours.
The safety colour code: red and yellow
29 CFR 1910.144 is the safety colour code for marking physical hazards. Its current text names two colours. Red is the basic colour for fire protection equipment, danger and stop: danger signs are painted red, red lights go at barricades and temporary obstructions, and emergency stop bars and emergency stop buttons are red, 1910.144(a)(1). Yellow is the basic colour for caution and for marking physical hazards such as striking against, stumbling, falling, tripping and caught in between, 1910.144(a)(3).
That is all the section says about colours. It does not give OSHA colours for aisles, material, scrap or holds. Floor marking schemes such as blue for materials or green for finished goods are a plant's own standard, so write yours down, post it and do not reuse red and yellow for something else. The floor marking color guide is a fill-in standard for that.
| Colour | Means | Where it comes from |
|---|---|---|
| Red | Danger, stop, fire protection equipment | 29 CFR 1910.144(a)(1) and 1910.145(d)(2) |
| Yellow | Caution, trip and strike hazards | 29 CFR 1910.144(a)(3) and 1910.145(d)(4) |
| Green with white | Safety instruction | 29 CFR 1910.145(d)(6) |
| Orange | Warning, recommended for warning tags | 29 CFR 1910.145(f) Appendix A (recommended, not mandatory) |
| Any other colour | Whatever your written plant standard says | Your plant standard |
Exit signs and Not an Exit signs
Exit signs are covered by 29 CFR 1910.37(b). Each exit must be clearly visible and marked by a sign reading Exit, 1910.37(b)(2). The sign must have the word Exit in plainly legible letters not less than six inches high, with the principal strokes at least three-fourths of an inch wide, 1910.37(b)(7). Each exit sign must be illuminated to a surface value of at least five foot-candles by a reliable light source and be distinctive in colour, 1910.37(b)(6). Self-luminous or electroluminescent signs with the minimum luminance in that paragraph are permitted.
Direction signs apply where the way to the exit is not immediately apparent: signs must be posted along the exit access to show the direction of travel to the nearest exit, and the line of sight to an exit sign must stay clear, 1910.37(b)(4). A doorway that could be mistaken for an exit must be marked Not an Exit or similar, or by a sign showing its use, such as closet, 1910.37(b)(5). Exit route doors must be free of decorations or signs that hide the door, 1910.37(b)(3). The same walk covers the plan in the emergency action plan guide.
ISO 7010 safety signs and symbols: the shape system
ISO 7010 is the international standard for registered safety signs. It does not group signs by signal word. It groups them by shape and colour, so a person who cannot read the language can still tell a prohibition from an instruction. The shapes and colours come from ISO 3864-1, the colour and shape standard that ISO 7010 builds on, and the table follows its category table. Check the standard itself, or your local rules, before you order signs, because the legal requirement depends on the country.
| Category | Message | Shape and colour | Example |
|---|---|---|---|
| Prohibition | You must not do this | Red circle with a diagonal bar | No open flame |
| Mandatory | You must do this | Blue circle with a white symbol | Wear eye protection |
| Warning | Hazard ahead | Yellow triangle with rounded corners and a black symbol | Hot surface |
| Safe condition | Where to go for safety or an exit | Green square | Emergency exit |
| Fire equipment | Where firefighting equipment is | Red square | Fire alarm call point |
Each registered sign has a code, such as P002 for no smoking. A plant that uses ISO signs uses the registered picture, not its own version.
A site can mix systems, but not on one hazard. If the press has an OSHA style caution sign on the guard and an ISO warning triangle on the door, people learn two meanings for the same risk. Choose one system per site, or per product line if you ship to a country that requires the other, and keep a one page legend that shows both.
Signal words, wording and design
29 CFR 1910.145(e)(2) sets the rule for wording: it should be easily read and concise, contain enough information to be understood, make a positive rather than a negative suggestion and be accurate in fact. In practice that means Keep Guard in Place beats Do Not Operate Without the Guard. One hazard, one instruction, as few words as will do.
All signs must have rounded or blunt corners and be free of sharp edges, burrs and splinters, and the fasteners must not be a hazard, 1910.145(d)(1). For tags, the signal word must be readable at a minimum distance of five feet or more where the hazard needs it, and tags must be affixed as close as safely possible to the hazard by a positive means such as string, wire or adhesive that stops loss or unintentional removal, 1910.145(f)(4).
- Say what the hazard is and what to do, in as few words as will do.
- Put the sign at the point of the hazard, at the height and distance where a person sees it before the risk, not at the room entrance only.
- Use pictures alongside text for mixed-language crews, and put each language the crew reads on the same sign.
- Train people on what each class means. 1910.145(c) asks that employees are instructed on danger and caution.
- Do not stack three signs on one machine. A person reads one.
Worked example: auditing the signs in a plant
Illustrative. A plant walks every area with a list of signs and checks each against the plant standard: right class and colour, legible from the distance the hazard needs, undamaged, and at the hazard. The numbers are made up to show the working.
| Area | Signs found | Meets standard | Faded or damaged | Wrong class or wording | Missing |
|---|---|---|---|---|---|
| Press shop | 24 | 20 | 3 | 1 | 2 |
| Assembly | 18 | 15 | 2 | 1 | 0 |
| Warehouse | 12 | 9 | 2 | 1 | 3 |
| Total | 54 | 44 | 7 | 3 | 5 |
Check: 24 + 18 + 12 = 54 signs found. 20 + 15 + 9 = 44 meet the standard. 3 + 2 + 2 = 7 faded and 1 + 1 + 1 = 3 wrong. 44 + 7 + 3 = 54, so every sign is counted once. Meets standard is 44 / 54 = 81.5 percent. The 5 missing signs are signs the standard calls for that were not found, so they are not in the 54.
The result is 10 signs to replace (7 faded plus 3 wrong) and 5 to install. The three wrong ones were caution signs on hazards that could kill, so they became danger signs. The warehouse had the most gaps and the lowest score, 9 of 12 or 75 percent, against 83.3 percent in the press shop (20 of 24) and 83.3 percent in assembly (15 of 18). Re-audit that area first. Put the rest on the monthly walk.
Common mistakes with safety signs
- Danger on everything. When every sign says danger, none of them means it.
- A sign instead of a fix. A sign does not remove a hazard. Control it first, with the hierarchy of controls, and use the sign to warn of what remains.
- A mix of old and new designs after years of one-by-one replacement. 1910.145(a)(2) says replacements follow the specification.
- Faded, painted over or hidden behind a rack. A sign no one can see is not a sign.
- A language the crew does not read. Use pictures and the languages on the floor.
- Floor tape colours that clash with the sign colours. Write one plant standard.
- No owner. Name who orders, places and audits signs.
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Report and control hazards in LeanSuite
Workplace safety in manufacturing, run from one platform: report hazards in seconds, fix them with tracked actions, train people and see safety KPIs on your tier boards.
Go deeper
This page is the short version. These guides cover each part in full.
- Visual Management in Lean ManufacturingHow signs, floor marking and boards work together as one visual system on the floor.
- Top Five Common Manufacturing HazardsThe hazards that most need a sign, and the controls that should sit behind it.
- Building a Proactive Safety Culture in ManufacturingWhy people notice and act on signs when the culture rewards speaking up.
- Near Miss Reporting That Actually Prevents Future IncidentsHow to capture the near misses that show a sign is missing or ignored.
All our articles on this subject are in the safety management topic.
Free templates and tools
- Shop floor safety rules posterFive basic rules in large type for the entrance and the break room.
- PPE by zone posterWhich protective equipment each zone requires, to sit beside the zone sign.
- Floor marking color guideA floor marking color standard with swatches, marks and line widths to fill in, and a floor marking check with a layout sketch.
- Safety audit checklistThirty-four plant-wide safety checks answered Yes, No or N/A, scored by area, with a risk rating and an action for every No.
- Visual management audit checklist29 checks of whether anyone can tell normal from abnormal at a glance, scored by group, with a trend and actions.
- Safety observation card templateFour behavior-based safety cards per sheet, with safe and at-risk checks, the conversation and a tally sheet.
- Emergency action plan templateA written emergency plan for a plant: site facts, roles and backups, warden coverage, scenario steps and a drill record.
Doing this in LeanSuite
Workplace safety
Report hazards and near misses in seconds, route each to an owner with a due date, and run safety inspections from ready-made templates.
See Workplace safetySafety tags
Anyone on the floor reports a hazard, near miss or unsafe condition in seconds, it is routed to an owner and tracked until it is fixed.
See Safety tagsAudit management
Run recurring audits and inspections from templates, and every failed item becomes a tracked action with an owner.
See Audit management
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FAQ
Questions about safety signs
OSHA 29 CFR 1910.145(c) names three classes: danger signs, which warn of immediate danger and are red; caution signs, which warn of potential hazards or unsafe practices and have a yellow background; and safety instruction signs, which give general safety instructions and have a white background with a green panel. ISO 7010 uses a different system based on shape and colour.
Red. 29 CFR 1910.144(a)(1)(ii) says danger signs shall be painted red, and 1910.145(d)(2) specifies red, black and white using the colour samples of ANSI Z53.1-1967 or ANSI Z535.1-2006(R2011). Danger signs are for immediate danger where special precautions are necessary.
Under OSHA, 1910.145 has caution signs for potential hazards or unsafe practices, with a yellow background. The section recognises a warning tag for a hazard level between caution and danger, 1910.145(f)(7), and recommends orange for it. In ISO 7010, a warning sign is a yellow triangle for any hazard. Use one system per site so a word means one thing.
Under 29 CFR 1910.37(b)(7), the word Exit must be in plainly legible letters not less than six inches high, with principal strokes at least three-fourths of an inch wide. The sign must be illuminated to at least five foot-candles, 1910.37(b)(6), or be a self-luminous or electroluminescent sign meeting the luminance in that paragraph.
No. 29 CFR 1910.145(a)(1) and (b) say the sign specifications do not apply to plant bulletin boards or safety posters, which are education. Signs that mark a hazard, such as danger, caution and safety instruction signs, do. Check your local rules for other jurisdictions.
The OSHA sign section sets no inspection frequency. Many plants check signs on a monthly area walk and do a full sign audit once a year, replacing anything faded, damaged or hidden. Add a sign check to the area audit and the 5S audit so it happens without a separate project.
Related guides and tools
- Floor marking color guide: a written colour standard for aisles, equipment, holds and keep-clear zones
- PPE by zone poster: the protective equipment each zone requires, to hang beside the zone sign
- Visual management audit checklist: check that signs, boards and markings are current and visible
- Emergency action plan: the exit route, alarm and head count rules that exit signs support
- 5S: sort, set in order and shine, where floor markings and signs come together
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