Why safety signs matter on site
Safety signs give an instant, wordless instruction on a busy construction site, where workers may not all share a first language. Reading them correctly is a basic site skill, and the CSCS test checks that you can recognise each type on sight. The good news is that you do not have to memorise every pictogram: once you know the colour and shape rule, you can read a sign you have never seen before.
UK signs follow the Health and Safety (Safety Signs and Signals) Regulations 1996, and the symbols themselves follow the international standard BS EN ISO 7010. Together these set five categories, each with its own colour and shape. Here is what each one looks like and means.
The five categories at a glance
Start with the shape and colour. The shape tells you the kind of message, and the colour reinforces it: a round sign acts on behaviour, a triangle warns, and a square or rectangle gives information such as where to go.
Prohibition
Round
Warning
Triangular
Mandatory
Round
Safe condition
Square or rectangular
Fire-fighting equipment
Square or rectangular
Prohibition signs
Round · Red ring and red diagonal bar on a white background, black symbol
A prohibition sign is round, with a red ring and a red diagonal bar running over a black symbol on a white background. It tells you that an action is not allowed because it would create a risk. The red bar always sits over the symbol, so the message reads as a firm stop.
No smoking
No access for pedestrians
No naked flames
Warning signs
Triangular · Yellow background with a black border and a black symbol
A warning sign is a yellow triangle with a black border and a black symbol. It does not ban anything; it alerts you to a hazard nearby so you can take care and check what to do. The triangle shape is deliberately eye-catching.
General hazard
Risk of electric shock
Slippery surface
Mandatory signs
Round · Solid blue background with a white symbol
A mandatory sign is a solid blue circle with a white symbol. It tells you about an action you must take, most often wearing a specific piece of personal protective equipment. Treat it as an instruction you have to follow, not a suggestion.
Wear head protection
Wear eye protection
Wear ear protection
Wear foot protection
Safe condition signs
Square or rectangular · Solid green background with a white symbol
A safe condition sign is a green square or rectangle with a white symbol. It points the way to safety: escape routes, emergency exits, first-aid points and assembly areas. Green here means safe and where to go, not permission to start work.
Fire exit
First-aid point
Fire-fighting equipment signs
Square or rectangular · Solid red background with a white symbol
A fire-fighting equipment sign is a red square or rectangle with a white symbol. It marks where fire equipment is kept, such as extinguishers, alarm call points and hose reels. The red here is about fire equipment, so do not confuse it with a round red prohibition sign.
Fire extinguisher
Fire alarm call point
How to read any safety sign
If you cannot read the wording, the shape and colour still tell you what to do. A red round sign with a bar means do not. A blue round sign means you must. A yellow triangle means take care. A green square shows the way to safety, and a red square locates fire equipment. Learn that pattern and the test becomes far easier.
Test yourself on safety signs
Reading this guide is the first step. To make the rules stick, practise with real CITB-style questions. Our free CSCS safety signs test asks you to identify sign types, colours and meanings, with an explanation on every answer so you learn from any mistake.
Keep revising the rest of the syllabus
Safety signs are one topic of the CITB Health, Safety and Environment test. When you are confident here, use our free CSCS mock tests to cover the rest, then take a full 50-question mock test to check you are ready. Closely related topics include fire prevention and emergency procedures.