Find out more below about some of the language you may come across when you need to think about illuminating potentially explosive atmospheres.

Just a few of the words you may come across in the Hazardous Area lighting world

Just a few of the words you may come across in the Hazardous Area lighting world

Hazardous Areas can be quite complex and even a little intimidating to people new to the industry.  To try and take some of the mystery out of it, we've listed some of the most common questions we get asked below, and below that there's a glossary of some of the most common terms you may come across.  If you're still struggling, you can always get in touch with us at info@wolfsafety.com 


    A Hazardous Area is an area where the presence of potentially explosive or flammable materials, such as gases, vapours, liquids, or dust, creates a risk of fire or explosion. The user must know the hazard before selecting the appropriate equipment.


    Regular lighting fixtures can ignite explosive or flammable substances. Specialized Hazardous Area lighting fixtures are designed to prevent sparking or hot surfaces capable of igniting the hazard ('T' - class rating)


    There are a number of concepts of safety - a "flameproof" lamp is designed to contain an ignition within the enclosure; "Ex e" and "Ex i" lights are designed to be safe even under fault conditions. Fault temperatures are measured and known.


    The IP rating indicates the degree of protection a light fixture offers against solids (first digit) and liquids (second digit). Liquid inside a product can cause short circuit damage.


    Hazardous Areas contain Zones based on the likely presence of explosive atmospheres. In Zone 0 Gas & Zone 20 Dust, the hazard is likely to be present continuously for more than 1,000 hours p.a., whereas in Zone 1/21, it’s present for less than 1,000 hours


    1. The Zone
    2. The Hazard
    3. The gas group
    4. The product "T-class"
    5. The ambient temperature of the Zone


    In Europe, compliance to the ATEX Directive is achieved by third party certification who will supply an ATEX certificate. For the rest of the world, IECEx certificate to harmonised standards.


    Follow the instructions. Installation should adhere to guidelines specified by relevant safety standards. Ensure proper grounding, proper sealing, and the use of suitable conduit and cable glands.


    Regular inspection and maintenance are crucial - for details see the specific product's instructions. Clean fixtures to prevent the buildup of dust or debris that might compromise their functionality.




    Emergency lighting (i.e. with backup battery power) should be included in lighting schemes to ensure illumination in case of power failures. Personal lighting, for example torches, should also be carried by operators working in hazardous environments.


    Yes, Most of Wolf's products have LED light sources.

  • Is Wolf registered with an EEE (Electrical and Electronic Equipment) compliance scheme and what is Wolf’s EEE Producer number?

    As a UK manufacturer, Wolf is registered as an EEE producer with an Environment Agency approved UK compliance scheme. Wolf’s EEE Producer number is WEE/DF0054TQ

  • Is Wolf registered with a Battery Producer compliance scheme and what is Wolf’s Battery Producer number?

    Wolf is registered as a battery producer with an Environment Agency approved UK compliance scheme. Wolf’s Battery Producer Number is BPRN00360


Please see below some of the most common terms used when talking about Hazardous Area lighting:

Ambient lighting

Ambient lighting refers to the general, uniform illumination in a room or space. It provides overall lighting that helps people navigate and perform tasks in a space comfortably and safely.

Ambient Temperature

Ambient temperature refers to the temperature of the surrounding environment where potentially explosive atmospheres may exist. Ambient temperature is a critical factor in ATEX because it can have a significant impact on the safety of equipment and processes in these environments. Ex equipment has a temperature class based on use in an ambient of -20°C to +40°C unless otherwise stated e.g. -30°C≤Ta≤55°C


In a hazardous area context, "anti-static" refers to the property or measures taken to prevent the build-up and discharge of static electricity in environments where flammable gases, vapours, or dust particles are present. Static electricity can accumulate on surfaces, equipment, or even on individuals as they move, and if discharged, it can ignite these hazardous materials and potentially cause explosions or fires. Tools, machinery, and equipment used in hazardous areas may be designed with anti-static features to prevent sparks.


ATEX stands for "Atmosphères Explosibles," which is a French term that translates to "Explosive Atmospheres" in English. ATEX refers to two European Union directives that outline the requirements for equipment and protective systems intended for use in potentially explosive atmospheres


A bulkhead light is a type of outdoor or indoor light fixture that is designed to be durable, weather-resistant, and functional. It is commonly used in commercial, industrial, and maritime applications. The term "bulkhead" in this context refers to a structural wall or partition that separates different sections within a ship, building, or other structure.  Bulkhead lights are characterized by their robust construction, often featuring a sturdy housing made from materials like metal or heavy-duty plastic, and a diffuser or lens that protects the light source from environmental elements like dust, moisture, and debris. 

They are commonly used in areas where traditional light fixtures might be vulnerable to damage or where additional protection is needed. Bulkhead lights can be found in applications such as pathways, stairwells, entryways, garages, docks, industrial facilities, and more. They can be mounted on walls or ceilings, providing illumination while maintaining a level of durability and resistance to environmental factors.

See Wolf's range of Bulkead lighting here

Cable Management

Cable management refers to the organization and arrangement of cables and wires in a neat and efficient manner and is essential to maintain safety when powered temporary lighting is used in Hazardous Areas. Wolf has a range of accessories that includes Magnet Cable Tidies

Cable Reel

A cable reel, also known as a cable drum or cable spool, is a cylindrical drum or spool on which electrical cables, wires, or other types of cables are wound for storage, transportation, and deployment.  See here Wolf's ange of Hazardous Area cable reels

Candela (cd)

A candela (symbol: cd) is the base unit of luminous intensity in the International System of Units (SI). It measures the amount of light or luminous flux emitted in a specific direction by a light source. It's important to note that the candela specifically measures the brightness perceived by the human eye, taking into account the varying sensitivity of human vision to different wavelengths of light

CE Mark

The CE mark, short for "Conformité Européene," is a certification mark that indicates a product's compliance with European Union (EU) health, safety, and environmental protection standards.


Certification is highly important for ensuring the safety of equipment and systems used in potentially explosive atmospheres.  Wolf products are certified to ATEX and IECEx standards.  Always look at the certification when purchasing Ex products; the product will have an ATEX certification.

Concept of Safety

Several concepts and methods are employed to ensure safety in ATEX environments, including:

  • Flameproof (Ex d): Flameproof or "Ex d" is a protection method designed to contain any explosion within the equipment itself to prevent it from igniting the surrounding explosive atmosphere

  • Encapsulation (Ex m): Encapsulation involves enclosing electrical components in a way that prevents any arcs, sparks, or excessive temperatures from occurring within the equipment

  • Intrinsic Safety (Ex i): is a protection technique which aims to limit electrical and thermal energy to levels that cannot ignite the surrounding explosive atmosphere

  • Increased Safety (Ex e): involves designing equipment and enclosures to reduce the risk of sparking, heating, or other potential sources of ignition

  • Non-Sparking (Ex n): is designed to minimise the risk of sparks or arcs occurring during normal operation

  • Pressurization (Ex p): involves maintaining a positive pressure within an enclosure, preventing the ingress of flammable gases or dust.  This method ensures that the explosive atmosphere cannot come into contact with electrical or mechanical components

  • Purge and Pressurization (Ex px and Ex py):  involve a combination of purging to remove any potentially explosive atmosphere followed by maintaining positive pressure.  This approach is used in situations where a continuous presence of hazardous material is not guaranteed

  • Powder Filling (Ex q): involves filling enclosures with a fine quartz powder to reduce the risk of sparking.  It's used for equipment like motors or transformers that may have internal sparking

Confined space

Confined Spaces are small, restricted, and not designed for continuous occupancy with limited entry and exit points, making it difficult for workers to escape in case of an emergency.  Examples of Hazardous Area Confined Spaces include tanks, silos, storage bins, manholes, tunnels, sewers, and utility vaults. 

CRI (Colour Rendering Index)

The Colour Rendering Index (CRI) is a metric used to measure how accurately a light source renders colours when compared to a reference light source with the same colour temperature. In simpler terms, it indicates how well a light source can reproduce the true colors of objects under its illumination and is measured on a scale of 1 to 100.


The ATEX "directive" refers to a legal document issued by the European Union that outlines specific requirements and regulations for the design, manufacture, and use of equipment and protective systems in potentially explosive atmospheres.

DLO (Directional Linear Optics)

Directional Linear Optics (DLO) is Wolf’s revolutionary patented light delivery technology which combines all the benefits of fluorescent and LED technology, whilst eliminating the drawbacks of both. Read more about it here


DSEAR stands for the Dangerous Substances and Explosive Atmospheres Regulations. It is a set of regulations in the United Kingdom that deal with the control of substances that have the potential to create explosive atmospheres and the risks associated with them. DSEAR regulations are closely related to the ATEX directives of the European Union and is the implementation of ATEX regulations within the UK legal framework.

EC type approval

EC/EU type approval is a certification process that ensures that certain products meet the regulatory and technical requirements set by the European Union (EU) for their safety, environmental impact, and other relevant characteristics. This process is designed to ensure that products placed on the market within the EU adhere to specific standards and regulations, thereby promoting consumer safety, environmental protection, and fair competition.

EC/EU type approval is required for a wide range of products, especially those with safety or environmental implications, including Electronics and Electrical Equipment, including lighting.

Emergency (Function)

Emergency lighting is designed to provide illumination in case of a power outage or other emergency situations where the regular lighting system fails. The emergency function ensures that certain lights continue to operate even when the main power source is no longer available.


EMC refers to the ability of electronic and electrical equipment to function properly in their intended electromagnetic environment without causing unacceptable electromagnetic interference to other equipment in that environment. In the context of Ex rated equipment, EMC is crucial for safety, reliability and regulatory compliance.  


The "Ex" marking indicates that the equipment or device has been specifically designed, tested, and certified to meet the safety requirements for use in these potentially hazardous environments. 

Extension Cable

An extension cable is a length of electrical cable with a plug at one end and a socket at the other end. Its primary purpose is to extend the reach of an electrical or electronic device, allowing it to be connected to a power source that is further away.  To see our range of Hazardous Area extension cables click here

Ex Zone

An Ex Zone, also known as a Hazardous Area or explosive atmosphere zone, refers to a location where potentially explosive atmospheres may be present due to the presence of flammable gases, vapours, mists, or dusts. The classification of Hazardous Areas into Ex Zones is based on international standards, such as the IEC 60079 series of standards. These standards categorize Hazardous Areas Zones based on the likelihood and duration of the presence of explosive atmospheres. 


A floodlight is a powerful lighting fixture designed to illuminate a large area with a broad and intense beam of light. See our temporary floodlights here and our range of installed floodlights here 

Harmonised Standard

Harmonised standards in the context of ATEX are technical standards recognized by the EU that provide a framework for ensuring the safety of equipment and protective systems used in potentially explosive atmospheres, helping manufacturers and users achieve compliance with ATEX Directive.

Hazardous Area

A Hazardous Area refers to a location where the presence of potentially dangerous substances or conditions pose a significant risk to the health and safety of people, property, or the environment. Such areas require specialised safety measures, equipment, and protocols to minimize the risks and ensure the safety of workers and the surrounding environment. Hazardous Areas are often classified into zones based on the likelihood and duration of the hazard.


A highbay light is a type of lighting fixture designed specifically for illuminating large indoor spaces with high ceilings. These fixtures are commonly used in commercial and industrial settings where there is a need for intense and efficient lighting.  They can be mounted in various ways, including hanging from the ceiling, suspended by chains or cables, or attached directly to a ceiling or beam. Our highbay range can be seen here 


HSE stands for the Health and Safety Executive. It is the regulatory body responsible for ensuring workplace health and safety in the United Kingdom. The HSE's primary mission is to prevent work-related injuries, illnesses, and accidents by enforcing health and safety regulations, providing guidance to employers and employees, conducting inspections, and promoting best practices.


IECEx stands for "International Electrotechnical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres." It's an international certification system for equipment, services, and personnel working in environments where there is a risk of explosions due to flammable gases, vapors, liquids, or combustible dusts.  It is generally used in countries outside Europe (except the USA).


INMETRO stands for "Instituto Nacional de Metrologia, Qualidade e Tecnologia," which translates to the "National Institute of Metrology, Quality, and Technology" in English. INMETRO is a Brazilian government agency responsible for promoting quality, safety, and technological development in various sectors of the economy.

Intrinsic Safety

Intrinsic Safety (IS) is a design concept and a set of standards used to ensure the safe operation of electrical and electronic equipment in hazardous or potentially explosive environments. This is achieved through a combination of design principles, equipment construction, and electrical components that prevent the generation of sparks, arcs, or high temperatures that could potentially trigger an explosion

IP Rating

An IP rating, which stands for "Ingress Protection" or sometimes "International Protection," is a standardized system that classifies and rates the degree of protection provided by an enclosure or casing against the intrusion of foreign objects (like dust and dirt) and moisture (such as water). IP ratings are often used to indicate the durability and environmental suitability of electronic devices, electrical equipment, and other products that may be exposed to various conditions.

The IP rating is composed of two digits:

  1. The first digit indicates the level of protection against solid particles, like dust and dirt. It ranges from 0 to 6, with higher numbers indicating better protection.

  2. The second digit indicates the level of protection against liquids, particularly water. It ranges from 0 to 9, with higher numbers indicating better protection

Installed Lighting

The lights are permanently fixed in place in the hazardous area and will remain there for permanent use. See our Installed Lighting range for safe use in potentially explosive atmospheres here


An LED, or Light Emitting Diode, is a semiconductor device that emits light when an electric current passes through it. Unlike traditional incandescent or fluorescent light bulbs, LEDs do not rely on heating a filament or using a gas to produce light. Instead, they generate light through a process called electroluminescence, which involves the movement of electrons within a semiconductor material

Light Fitting

A light fitting, also known as a luminaire or light fixture, is an electrical device designed to house and protect a light source (such as a light bulb or LED) and to distribute and direct light in a specific way. .

Lighting Design Service

A lighting design service is a service offered by independent specialists and lighting manufacturers who use software such as Dialux, Radiance or Lumen Designer, to plan, calculate and visualise lighting for both indoor and outdoor areas, and to produce a lighting scheme for a work area with lighting levels:

  • that ensure the safety for people in the work environment
  • that are optimised for the specific tasks being carried out in the work area
  • that conform to the standards required in the industry and country
  • that minimise power consumption to achieve the required lighting levels

To read more about Wolf's lighting design service, click here


A linear light fitting refers to a type of lighting fixture that is designed in a linear or elongated shape. The linear shape allows for a more even distribution of light over a larger area compared to traditional point-source fixtures like bulbs or spotlights. LED linear fixtures consist of multiple LED light sources arranged along a linear housing. To see our temporary linear lights click here and for our installed linear lights click here 


Wolf Safety's LinkEx™ range consists of luminaire and floodlight units which are supplied fitted with integral sockets and can be quickly and easily interconnected to provide a fully scale-able temporary lighting installation for any size of hazardous area work task. 

Low Voltage

Low voltage is used primarily for safety reasons as it reduces the risk of electric shock. Low voltage lighting in Hazardous Areas can also be used to minimize the risk of ignition and explosion while providing adequate illumination for necessary tasks. It is typically used in tanks, with a maximum 50V voltage because of the risk of electric shock.

Lumen (lm)

A lumen (symbol: lm) is a unit of measurement used to quantify the amount of visible light emitted by a light source. It measures the brightness or luminous flux of light as perceived by the human eye.


A luminaire is a complete lighting unit, including a light source (e.g. the LEDs), the housing or fixture that holds the light source in place, and any necessary components for controlling the light output, such as reflectors, lenses, and diffusers.

Lux (lx)

Lux is a unit of illuminance, which measures the amount of light that falls on a surface. It is defined as one lumen per square meter (lm/m²). In simple terms, it indicates the brightness of light on a surface.  Wolf help users chose the correct product for their application by higlighting the lux measurement for each product.


Formerly, Hazardous Area lighting products had to comply with safety standards for optical radiation which was shown in the certification as ‘op is’ , where  op = optically and is = inherently safe. 

Portable Lighting

The lights are generally carried in and out of the hazardous area by the operator and used for short periods; they are generally lightweight and for personal use, for example, torches, hand lamps, and headtorches. To see our Portable Lighting range, click here 

Primary Cell

A primary cell, also known as a primary battery or non-rechargeable battery, is a type of electrochemical cell that generates electrical energy through an irreversible chemical reaction. Unlike rechargeable batteries (secondary cells), primary cells are designed to be used once and then discarded after their chemical reactions have been exhausted.

Rechargeable Cell

A rechargeable cell, also known as a rechargeable battery or secondary cell, is a type of energy storage device that can be charged and discharged multiple times. Unlike disposable batteries (primary cells), which are designed for single-use and are discarded after their energy is depleted, rechargeable cells can be recharged and reused, making them more cost-effective and environmentally friendly in the long run


RoHS stands for "Restriction of Hazardous Substances." It is a European Union directive that restricts the use of certain hazardous substances in electrical and electronic equipment.

Safety Lamp

A safety lamp is a type of lamp specifically designed for use in potentially hazardous environments where flammable gases or dust are present. The primary purpose of a safety lamp is to prevent the ignition of these flammable substances, which could lead to explosions or fires. Safety lamps were historically used in coal mines to provide illumination for miners while minimizing the risk of igniting methane gas, which is commonly found in coal mines and can be explosive.

Safety light

In a hazardous area context, a safety light refers to a specialized lighting device designed to be used in environments where there is a risk of explosion, fire, or other safety hazards due to the presence of flammable gases, vapors, liquids, dust, or other combustible substances. They are constructed to minimize the risk of igniting the surrounding atmosphere. 

Key features of safety lights for hazardous areas may include:

  1. Intrinsically Safe Design: The electrical components of the light are designed to prevent the generation of sparks, arcs, or high temperatures that could potentially ignite a hazardous atmosphere.

  2. Explosion-Proof Housing: The light is housed in a rugged and sealed enclosure that can withstand pressure and prevent any internal sparks or heat from escaping and igniting the surrounding atmosphere.

  3. Low Heat Output: Safety lights are designed to produce minimal heat.

  4. Sealed Construction: The lights are designed to be dust-tight and water-resistant.

  5. Certifications: These lights typically undergo rigorous testing and certification processes to ensure they meet industry standards and safety regulations, such as ATEX (Europe), IECEx (International), and other regional certifications.


Wolf’s unique and patented SOVI™ function keeps you safe by alerting the user if lights are running outside the certified and optimal operating voltage ranges, maximising both safety and performance. To read more about SOVI™ click here  

Splitter Box

A splitter box, also known as a distribution box or junction box, is an electrical enclosure that is used to split or distribute electrical power or signals to multiple devices or circuits. It serves as a central point where electrical connections can be made, allowing one input to be divided into multiple outputs. For our range of splitter boxes, click here

Task Lighting

Task lighting refers to a type of lighting that is specifically designed and positioned to provide illumination for a particular task or activity

Tank Lighting Kit

Tank Lighting kits are combinations of lights, power supplies, cables, plugs, and sockets which allow a flexible setup of high quality task and ambient lighting for working in tanks and vessels. Read more about Wolf Tank Lighting Kits here  

Temperature Class ("T-class", "T-rating")

Temperature class relates to the hot surface ignition temperature of a particular explosive gas, vapour or mist atmosphere. It must not be exceeded by the temperature classification of the equipment intended to be used in that atmosphere. There are several different temperature classes, each denoted by a letter and number - T1, T2, T3, T4, T5, T6 - with T1 being the lowest and T6 the highest. The majority of hazards are either T3 or T4.  Ambient temperature is very significant in determining whether a product is suitable for a particular ATEX zone

Temporary Lighting

With temporary lighting, the lighting equipment is moved into the hazardous work area and set up, remaining in place until the job is done before being removed.  The lights might remain in the hazardous area for just a few hours or stay there for several months. Our Temporary Lighting page is here 


An electrical transformer is a device used to transfer electrical energy between two or more electrical circuits through electromagnetic induction. It does this by changing the voltage level of an alternating current (AC) electrical supply while keeping the frequency of the AC signal constant. Typically, the operating output is below 50V for products being used in tanks. To see Wolf transformers, click here 


UKCA stands for "UK Conformity Assessed." It is a marking used for certain products placed on the market in Great Britain (England, Scotland, and Wales) after the UK's departure from the European Union. 


UKEX is an abbreviation of UKCA Ex Certification and is part of the certification scheme of the UKCA assessment for Ex products sold in England, Scotland and Wales. 


WEEE stands for "Waste Electrical and Electronic Equipment." It refers to a directive and regulatory framework established in the European Union (EU) to address the management and disposal of electronic waste.


A worklight is a transportable source of illumination designed to provide additional light in workspaces where the existing lighting may be insufficient. For our range of worklights, see here

Please note

The information provided in the Frequently Asked Questions (FAQ) section of this website is intended to be helpful and informative to the best of our knowledge.  However, we cannot guarantee the accuracy, completeness, or timeliness of the information presented.  The content in the FAQ section is subject to change without notice, and we do not make  any  representations or warranties, express or implied, regarding its accuracy or reliability.

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