Warning signs

What is a warning sign?

A warning sign is the type of safety sign that draws attention to a hazard. It does not require any particular action and it does not prohibit anything: it indicates that a risk is present at that location or on that piece of equipment. This is why its appearance is standardised and recognisable from a distance: a triangular shape, yellow background, black pictogram with a black border. The yellow covers a substantial part of the sign surface so that it stands out even in peripheral vision.

In practice, the purpose of a warning sign is to buy time. Employees, visitors and contractors should learn about the risk before they enter its range, leaving room to slow down, put on protective equipment or avoid the area altogether.

What hazards can a warning sign indicate?

Physical and mechanical risks

• slippery surface, trip hazard, steps
• falling from height, open shaft or floor opening
• risk of head injury, low headroom
• moving machine parts, automatic start-up
• forklift traffic, lifted load, suspended load
• hot surface, low temperature

Chemical, fire and explosion hazards

• corrosive substance, toxic substance, harmful substance
• flammable substance, oxidising substance
• explosive substance, potentially explosive atmosphere
• pressurised cylinder, gas hazard

Electrical and radiation hazards

• risk of electric shock, electrical equipment
• laser beam, non-ionising radiation
• ionising radiation, strong magnetic field

In many cases a warning sign is not sufficient on its own: it can be specified with a supplementary text panel, or combined with a mandatory or prohibition sign where controlling the risk also calls for specific behaviour. The pictograms available can be reviewed in the product list.

Where are warning signs used?

• production halls, machine lines, presses and automated equipment
• warehouses, forklift traffic routes, loading bays, high-bay storage
• construction sites, site compounds, shafts and open excavations
• maintenance workshops, boiler rooms, compressor rooms, electrical rooms
• laboratories, chemical stores, welding and paint stations
• cold stores and areas around steam and hot water pipework
• plant rooms in institutions, schools and office buildings
• temporary risks: wet floor after cleaning, a section under repair

Temporary situations deserve particular attention. Maintenance, refurbishment or cleaning often calls for a warning sign that is only needed for the duration of the work and can be removed afterwards – portable and easily removable formats are suited to this.

Consistent appearance under ISO 7010

The purpose of the international standard ISO 7010 is to keep the shape, colour and pictogram of safety signs identical across countries. Within this system, warning signs carry reference codes beginning with the letter "W". Across the European Union, minimum requirements for safety and health signs at the workplace are set out in Directive 92/58/EEC, implemented in national legislation and built on the same set of symbols, which is why the signs available on the market share a broadly consistent visual language.

The practical benefit is that on multilingual sites, where contractors come and go, and across several locations of the same company, the meaning stays the same. Information about the standard compliance of any individual product should always be interpreted on the basis of the details given on that product page.

Sign or sticker? Choosing the format and material

• Self-adhesive sticker: for smooth, clean and dry surfaces such as machine housings, control cabinets, doors and handrails. Quick to apply, economical in smaller sizes and well suited to signs placed directly on equipment.
• Rigid plastic or foamed PVC sign: for walls, posts and fences, where there is no suitable surface for adhesive or a larger size is needed. Fitted with mounting holes or double-sided tape.
• Metal sign: for durable outdoor mounting and locations exposed to heavy use.
• Photoluminescent version: appropriate where the hazard remains present during a power failure or in poor lighting.

Indoor and outdoor use

Indoors, the mounting surface, ease of cleaning and chemical resistance are the main considerations – in wash-down production areas or laboratories, for example. Outdoors, UV resistance, moisture resistance and tolerance to temperature changes become important, so a weather-resistant material is the safer choice, since print not intended for outdoor use may fade over time. The intended application of each product can be checked against the details shown on the product page.

Size, visibility and placement

Size is a functional matter rather than an aesthetic one: the sign has to match the recognition distance from which it needs to be noticed. A sticker on a control cabinet calls for a different size than a sign above a hall entrance or alongside a forklift route.

• placed before the hazard area, at the point of entry
• at eye level, or at a height clearly visible from the direction of travel
• unobstructed: not covered by stock, door leaves, racking or vehicles
• adequately lit, on a surface that does not cause glare
• not too many signs in one place, as this reduces their attention value
• checked regularly for cleanliness, fading, lifting edges and continued relevance

Common applications

• electric shock warning stickers on control cabinets and distribution boards
• corrosive and toxic substance signs in chemical stores
• forklift traffic signs alongside internal transport routes
• hot surface signs near steam pipework and furnaces
• slip and trip hazard signs at steps, ramps and freshly cleaned areas
• falling hazard signs at open shafts and excavations
• automatic start-up pictograms on machines that start without warning

Find the sign that matches the hazard

The product list can be browsed by pictogram, size and format. Based on the risk assessment, it is worth reviewing the machines, storage areas and traffic routes concerned in one pass, then replacing missing or worn signs together – this makes installation simpler and keeps the signage system consistent. For questions about the most suitable format, our team is available to help.

Frequently asked questions

What does a yellow triangular sign mean?

It draws attention to a hazard. The black pictogram on a yellow background indicates that a risk is present at that location, without giving a specific instruction – as opposed to mandatory signs, which require a particular action, and prohibition signs, which forbid one.

What is the difference between a warning sign and a mandatory sign?

A warning sign shows the hazard (yellow triangle), while a mandatory sign shows what has to be done about it, for example which protective equipment has to be worn (blue circle). The two are often displayed together: one indicates the risk, the other the way to control it.

What size should be chosen?

Size should match the distance from which the sign needs to be recognised. A smaller size is usually sufficient on a machine, a cabinet or a door, while a larger size is appropriate in a high-ceilinged hall, alongside a traffic route or outdoors.

Is a sticker or a rigid sign the better choice?

A sticker works well where there is a smooth, clean surface suitable for adhesive – the most practical option for signs placed on equipment. A rigid sign is preferable where the surface is uneven or dusty, where mounting is on a post or fence, or where the sign may need to be relocated later.

Are these signs suitable for outdoor use?

This depends on the material and the print. Versions intended for outdoor use are generally made from UV- and weather-resistant materials. The intended application can be checked in each case against the details on the product page.

Are custom sizes, custom wording or supplementary panels available?

For custom size or wording requirements, or for a supplementary text panel, please contact our customer service team, which can provide information on the available options and the expected lead time.