Hazardous Areas Classification & Installation

In this course the trainee will learn about; the characteristics of flammable materials, how hazardous locations are classified, types of equipment used in hazardous locations, typical wiring systems, and inspection and maintenance guidelines.

Hazardous areas exist in many industrial and commercial facilities where, in normal daily operations, process information is gathered using sensors, switches, and manually operated controls. During the manufacturing process, flammable materials are conveyed throughout the facility using conveyors, valves, pumps, forklifts, etc. Finished products are stored in tanks and vessels, loaded onto trucks and ships, and pumped for hundreds of miles through pipelines.
The hazard exists as a result of the release of a flammable material into the atmosphere. Releases occur due to, for example; leaks at valves and pipe flanges, from routine maintenance where a seal is being replaced, or where portions of a process result in the regular escape of gases and vapors.

In many jurisdictions, either government or company mandated training is required for those personnel working in these environments. There are many occupations and workers employed in this sector of industry that are affected by the safety requirements for working in hazardous locations. The focus of this unit of training is on activities performed by instrumentation and electrical personnel.

  • Agenda
  • Audience
  • Technical Information

Day 1
Nature and Grouping of Flammable Gases

    • Fire Triangle
    • Flammable Limits
    • Sources of Ignition
    • Flashpoint
    • Ignition Temperature
    • Gas Density

This topic explains the basic characteristics of flammable materials, as they relate to the installation of electrical equipment in hazardous (classified) areas where gases, vapors, and liquids are present.
Electrical equipment is specially designed and chosen for these areas, and a good understanding of these basic characteristics is necessary in order for electrical and instrumentation personnel to appreciate the selection and installation requirements for electrical apparatus.


Day 2
Hazardous Area Classification

    • Hazardous Location Classification (NEC)
    • Hazardous Location Classification (IEC)
    • Grouping of Gases
    • Temperature Classifications

This topic covers the methods used to classify hazardous areas. A Hazardous Area may contain flammable gases or vapors, combustible dusts, or ignitable fibers. There are different systems used in Europe and the United States to classify the type of hazard and whether the hazard is always present or only present in an emergency condition such as a spill or failure of ventilating equipment. In many cases the equipment is designed for the worst case, which would be to assume the explosive atmosphere is always present and the electrical or thermal energy available is the lowest required to cause a fire or an explosion.


Day 3
Electrical Enclosure Protection Methods and Marking

    • Flameproof (Ex “d‟) and Explosion Proof Apparatus
    • Increased Safety (Ex “e‟)
    • Intrinsic Safety (Ex “ia‟, Ex “ib‟)
    • Pressurization (Ex “p”)
    • Ingress Protection (IP) Codes - IEC
    • Apparatus Label Marking
    • Modification of Flameproof Enclosure

This topic covers suitable electrical equipment for use in hazardous areas. The objective of selecting electrical equipment and the means of installation is to reduce the hazard of the electrical apparatus to an acceptable level. An acceptable level might be defined as selecting protective measures and installation means to ensure that the probability of an explosion is not significantly greater due to the presence of electrical apparatus than it would have been had there been no electrical apparatus present.


Day 4
Wiring Systems for Hazardous Areas

    • Types of Cables Suitable for Hazardous Areas
    • Types of Cable Glands
    • Wiring Methods for Flameproof Equipment
    • Wiring Methods for Intrinsically Safe Equipment


The wiring systems used in hazardous areas in industrial facilities perform the same functions as the wiring systems in the non-hazardous (safe) areas of those same plants. They carry power to the energy consuming devices, and send and receive information from telecommunication, instrumentation, and control systems. These wiring systems run from safe areas to hazardous areas, travel within the different classified areas, and terminate in certified hazardous area apparatus. The relevant installation codes and practices specify the requirements for approved cables, glands, and fittings.

This topic covers the common wiring systems and components used with flameproof and intrinsically safe apparatus, and identify specific code requirements for their safe installation.


Day 5
Inspection and Maintenance

    • Inspection and Maintenance of Flameproof Installations
    • Inspection and Maintenance of IS Installations


This topic focuses on typical inspection and maintenance check lists for electrical apparatus used in hazardous locations according to recognized practices and manufacturer‘s recommendations. It emphasizes that apparatus will only remain approved or certified if it is maintained in accordance with the recommendations provided by manufacturers and the relevant construction standards.

This course is mainly targeted to electrical and instrumentation technicians working in the field as an introduction or refresher.

The course can also be applicable to employees working with equipment purchasing, procurement, storage, job planning as well as immediate supervisors to the working technicians.

Discipline:    Electrical / Instrumentation

Delivery type:   Classroom

Provider:    TPL

Possible Instructors: Fully qualified and certified TPL instructor with a minimum of 15 years instructor experience to international delegates in client or offsite locations.

Level:    Foundation

Course Version:      0

Length:       5 days

Skills Needed to
Take Course (pre-requisites):
    Anyone taking this course should familiar with electrical and or instrumentation installations in an industrial setting.