Prohibition Safety Sign FAQs

Written by the Technical Team at Caledonia Signs
Last reviewed: Sept 2026

Welcome to the Caledonia Signs Prohibition Safety Signs Knowledge Centre

Prohibition safety signs are an important part of workplace safety communication, clearly identifying actions, behaviours or activities that are not permitted. From preventing unauthorised access and prohibiting smoking to restricting the use of mobile phones or access to machinery, these signs help communicate important restrictions quickly and consistently across a wide range of environments.

Choosing and using the correct prohibition safety signs can raise many questions, including what the signs mean, where they should be displayed, which regulations apply, and which symbols should be used for particular restrictions. Understanding the purpose of prohibition signs, their colours, symbols and applications helps businesses communicate restrictions clearly and support safer working environments.

This page answers some of the most frequently asked questions about prohibition safety signs, including UK regulations, BS EN ISO 7010 standards, sign colours and symbols, placement, restricted activities and common applications. Whether you manage a factory, warehouse, construction site, office, school, laboratory or commercial facility, this guide provides practical information to help you understand and use prohibition signage effectively.

Effective prohibition signage should form part of a wider approach to workplace safety and risk management. By displaying clear and appropriate prohibition signs in the correct locations, businesses can help prevent unsafe behaviour, reinforce site rules and ensure important restrictions are clearly communicated to employees, contractors, visitors and members of the public.

What regulations apply to prohibition safety signs in the UK?

In the UK, prohibition safety signs used for workplace health and safety are covered primarily by the Health and Safety (Safety Signs and Signals) Regulations 1996. These regulations require employers to use appropriate safety signs where risks cannot be avoided or adequately controlled by other measures. Prohibition signs are used where particular behaviour or actions must be prevented because they could create or increase a risk to health and safety.

Prohibition safety signs should follow recognised design principles and standards, including BS EN ISO 7010 where applicable. They are normally circular and feature a black pictogram on a white background with a red border and diagonal red bar. This distinctive appearance allows prohibition messages to be recognised quickly and consistently.

Common examples include No Smoking, No Access for Unauthorised Persons, No Pedestrians, Do Not Touch, Do Not Extinguish with Water and restrictions relating to vehicles, machinery or specific workplace activities.

Employers should determine where prohibition signs are required through a suitable risk assessment and ensure signs are positioned where they can be clearly seen before a person reaches the area, activity or behaviour to which the restriction applies. Signs should remain visible, legible and in good condition.

What does a prohibition safety sign mean?

A prohibition safety sign means that a particular action, behaviour or activity is not permitted. These signs are used to prevent behaviour that could create or increase a hazard and to communicate restrictions clearly to employees, contractors, visitors and members of the public.

Prohibition signs are normally recognised by their circular shape, white background, black pictogram, red border and red diagonal bar. The red circle and diagonal line indicate that the action represented by the pictogram must not be carried out.

Common examples include No Smoking, No Entry, No Pedestrians, No Mobile Phones, Do Not Touch, No Open Flames, No Climbing and No Access for Unauthorised Persons.

Prohibition safety signs are commonly used in factories, warehouses, construction sites, schools, laboratories, commercial premises, car parks, machinery areas and other locations where particular behaviours or activities need to be restricted.

Where should prohibition safety signs be displayed?

Prohibition safety signs should be displayed where people need to understand that a particular action or behaviour is not permitted. They should normally be positioned so the restriction can be seen before a person enters an area, approaches equipment or carries out the prohibited activity.

Common locations include workplace entrances, restricted areas, machinery zones, warehouses, construction sites, workshops, laboratories, car parks, storage areas and locations where smoking, pedestrian access, vehicle access or particular activities are prohibited.

For example, a No Entry or No Unauthorised Access sign should be positioned at the entrance to the restricted area rather than further inside it. Likewise, a No Smoking sign should be clearly visible before entering an area where smoking is prohibited.

Signs should be clearly visible, appropriately positioned, well lit where necessary and not obscured by doors, equipment, stock, machinery or other objects. The location and number of signs required should be determined according to the risks and layout of the site.

Caledonia Signs Expert Tip: Display the Restriction Before the Prohibited Area or Activity

Prohibition safety signs are most effective when they are seen before a person reaches the point where the restriction applies. For example, a “No Entry” or “No Unauthorised Access” sign should be positioned at the entrance to a restricted area so that people understand the restriction before entering.

Use clear, recognised prohibition symbols where appropriate and make sure signs remain visible, legible and unobstructed. Sign locations should also be reviewed when workplace layouts, access arrangements, machinery or working practices change so that restrictions continue to be communicated effectively.

What actions can prohibition safety signs restrict?

Prohibition safety signs can be used to restrict a wide range of actions and behaviours where allowing the activity could create a hazard, interfere with safe working practices or breach site rules.

Common restrictions include No Smoking, No Vaping, No Open Flames, No Entry, No Pedestrians, No Unauthorised Access, No Vehicles, No Parking, No Mobile Phones, Do Not Touch, Do Not Climb and No Eating or Drinking.

Some prohibition signs relate directly to workplace hazards. For example, signs may prevent people from entering machinery areas, climbing on racking, using mobile phones in sensitive locations, introducing ignition sources into hazardous areas or using water on equipment or materials where doing so could create additional danger.

The correct prohibition sign should clearly reflect the activity or behaviour being restricted. Where a recognised ISO 7010 symbol exists, using the standardised pictogram can help ensure the message is understood consistently.

What symbol is used on prohibition safety signs?

Prohibition safety signs normally use a black pictogram on a white background surrounded by a red circular border with a diagonal red bar passing across the symbol. The red circle and diagonal line communicate that the activity represented by the pictogram is prohibited.

This standardised visual format makes prohibition signs easy to recognise and distinguishes them from other categories of safety signage such as blue mandatory signs, yellow warning signs and green safe-condition signs.

BS EN ISO 7010 contains internationally recognised prohibition symbols for many common restrictions. Examples include P002 No Smoking, P003 No Open Flame, P004 No Thoroughfare, P009 No Climbing and other symbols covering prohibited actions and access restrictions.

Where additional explanation is needed, a prohibition symbol may be accompanied by supplementary wording to make the restriction clear to people using the site.

What types of restrictions do prohibition safety signs communicate?

Prohibition safety signs communicate restrictions on actions, access and behaviour. Their purpose is to make it immediately clear that something must not be done or that entry to a particular location is not permitted.

Access restrictions can include No Entry, No Pedestrians, No Unauthorised Persons and No Vehicles. Behavioural restrictions can include No Smoking, No Vaping, No Eating or Drinking and No Mobile Phones. Other signs may prohibit activities such as touching machinery, climbing, operating equipment or using naked flames.

Prohibition signs are commonly used at entrances, around machinery and equipment, in factories and warehouses, on construction sites, in schools, car parks, laboratories and other controlled environments.

When correctly selected, positioned and maintained, prohibition safety signs provide clear visual communication of workplace restrictions and help reinforce rules established through risk assessments, safe working procedures and site management.

Looking for Prohibition Safety Signs?

Caledonia Signs is one of the UK's leading trade-only manufacturers of safety signage, supplying an extensive network of distributors throughout the UK and overseas. Our prohibition safety sign range includes No Smoking, No Entry, restricted access, machinery, parking and general prohibition signs in a variety of materials, sizes and formats.

If you're an end user looking to purchase prohibition safety signs, we'd still be delighted to help. Simply contact us with details of your requirements and we'll be happy to recommend a suitable distributor in your area.

Interested in becoming a distributor? Contact our team to discuss opening a trade account and gaining access to our full product range, trade pricing and online ordering portal.