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Arguably, the most dramatic changes contained in the 1998 edition of the Canadian Electrical Code (CEC), are those related to hazardous locations. With the exception of permitting the use of Teck Cable in Class I, Division 1 locations some fifteen years ago, Sections 18 and 20 have changed very little in decades. However in the 18th Edition of the code, the hazloc industry goes global.

Industrial facilities in which potentially explosive atmospheres exist have presented a challenge for codes and standards makers for decades. Area classification, equipment standards, installation and wiring codes of practice throughout the world which deal with these areas have evolved into two basic systems.

Traditionally, North America defined hazardous locations in terms of Classes and Divisions. Class I being flammable gases and vapours, Class II combustible dusts and Class III easily ignited fibres or flyings. Divisions 1 and 2 identified the conditions under which the hazard was present. Division 1 indicates the presence of the substance under normal operating conditions, while Division 2 defines the presence under abnormal conditions.

Most other countries deal with gases and vapours in a system, which separates the areas into Zones. In these countries, Class II and Class III areas are not specifically identified as hazardous locations. In some cases, North American technology is "exported" to a country to accommodate construction of facilities by large Canadian or US companies.

The changes in the 1998 CEC relate only to gases and vapours. In the main body of the code, Class I environments will now be defined as Zones. A new term replaces the old definition of flammable gases and vapours with explosive gas atmospheres. The two terms mean the same with the latter being the IEC definition.

The predominant standards writing organizations, which identify Zones, are the International Electrotechnical Commission (IEC) and the European Committee for Electrotechnical Standardization (CENELEC). The relative hazardous location standards from both organizations are basically the same. Since Canada is an active member of the IEC, those standards were adopted to form the new CEC.

The introduction of Zones to the CEC is not something that can simply be ignored by users. In the 1998 CEC, Divisions in Class I have been moved from main body of the Code to Annex J, and replaced with Zones. The intent of the code makers is that all new construction must use Zones.

This does not mean that Division installations will suddenly disappear. The scope of Section 18 says that for additions, modifications and renovations to, or operation and maintenance of existing facilities presently using the Divisions system for Class I, they can continue to use the rules now in Annex J.

It should be understood, while the CEC clearly gives preference to the IEC area classification system in Appendix B, it does not favour Division or Zone electrical equipment. Both are accepted, under specific rules, as providing equal levels of safety.

It is presumed that Divisions will continue to be used for the next few editions of the Code then likely disappear. The local authority having jurisdiction is expected to allow a grace period for users to become familiar with the new rules before they are strictly enforced. This will permit users to complete projects already in process.

The concept of Zones is not really that difficult to understand. Like Divisions, Zones are based on the probability of gases being present in the atmosphere in sufficient quantities for an explosion to occur. Divisions basically defined the normal and abnormal conditions, although industry groups such as the American Petroleum Institute (API) recommended that certain Division 1 locations should not use electrical equipment. Zones on the other hand, provide clearer definitions for area classification.

Industry practices in the IEC, offer guidelines which translate the various Zones into hours per year. The following chart compares the two systems;

The combination of Zones 0 and 1 equate to Class I, Division 1. Class I, Division 2, and Zone 2, are identical. By removing the most hazardous portion of Division 1, different methods of protection may be used in Zone 1 areas which reduces the need for the bolted enclosures used in the past. Given the increased risk associated with Zone 0, the code requires that all electrical equipment used in these areas must be intrinsically safe. Zone 0 comprises less than 2% of all hazardous locations.

The Zone classification system presents new challenges for designers. In the past, if the electrical designer was uncertain of an area classification, it was typically defined as Division 1 "to err on the side of safety". This lead to many over-classified facilities with electrical systems which were difficult to install and maintain correctly. In the Zone system, if the designer takes the "worst case" scenario of Zone 0, the only electrical equipment option available is intrinsically safe products. For this reason, it is expected that greater attention will be paid to "correct" area classification.

The next major change in the 1998 CEC involves gas groups. Previous editions grouped explosive gases according to common explosive characteristics as Groups A, B, C and D. Group A (acetylene) is the most volatile and Group D (gasoline, propane etc.) the least volatile. In the 1998 CEC (IEC system) there are three groups the most explosive Group C (combining acetylene and hydrogen) and Group A (gasoline, propane etc.). The IEC Groups are prefaced by "II" to indicate surface industries.

The 1998 CEC accepts either gas Group systems to be used in Zones. This is likely the most confusing change in the code. The following chart compares the two systems.

The next major change involves product marking. Traditional CSA standards require products be marked with the Class, Division is necessary only if a product is acceptable in Division 2 only, Gas Group and Temperature Code. For example Class I, Group C, T6 identifies a product for use in Class I, Divisions 1 and 2, Groups C and D, and for use with gases having an auto-ignition temperature above 85oC. The additional information is considered redundant by the standard.

In the 1998 CEC Ex of EEx indicates a product is approved for use in an explosive gas atmospheres. The Ex is the IEC designation whereas the EEx indicates CENELEC compliance. Since the two standards are essentially the same, the 1998 CEC® accepts both Ex and EEx on a product. Next is the type(s) of protection used. A product may use multiple protection methods as in the case of a contact block; the contact chamber is flameproof (d) and the contacts increased safety (e) therefore "de" would appear. The next symbol is a "I or II". The "I" is used to identify gaseous mines and the "II" to indicate surface industries. Since the CEC® does not deal with mining applications, only "II" is accepted. The final two designations are the IEC Gas Group and temperature code.

CSA adopted the IEC 79 Series of product standards, which are now recognized in the1998 CEC. Class I, Division 1, equipment was characterized by heavy cast enclosures with bolted or threaded covers. The new methods of protection are characterized by smaller non-metallic equipment such as shown below.

ontact block (Enlarged) with explosion proof chamber

Bolted enclosure (cut away view)

The Killark 8040 Series uses these small explosion proof housings in a non-metallic housing. This product is suitable for Class I, Zone 1, and Class I, Division 2, locations

The new methods of protection identified include; "d" Flameproof, "p" Pressurization, "i", "ia, and ib" Intrinsic Safety, "q" Sand Filled, "o" Oil Immersion, "e" Increased Safety, "n" Non Sparking, "m" Encapsulation. With the exception of type n, non-sparking, all are permitted in Zone 1. The code provides a chart to indicate the location in which a product may be used. All Zone equipment is acceptable in Class I, Division 2 and all Class I, Division 1, equipment is permitted in Zone 1. While there are now three types of intrinsic safety, ia and ib, only ia is permitted in Zone 0 (ia is identical to previous versions of intrinsically safe equipment certified by CSA with the symbol "i").

The wiring methods for Zone 1 are basically the same as Class I, Division 2. This is possible because of the addition of the Increased Safety type of protection. Increased Safety defines equipment that, under normal operating conditions, does not produce ignition-capable arcs or sparks or high temperatures. It provides special increased spacing between live parts and live parts of opposite polarity or grounded metal parts, special insulating materials to reduce the likelihood of arc tracking, special terminals to reduce the likelihood of high temperatures at loose connections, and temperature control on heat producing equipment.

The use of increased safety terminals eliminates the need for sealing fittings and permits the use of certain non-metallic enclosures. Seals sittings are required traditional Class I, Division 1, metal enclosures, which have no other means of sealing, in Zone 1 and 2 or Class I, Division 2 locations.

It is expected that users will inevitably re-classify existing facilities using the Zone system to limit confusion and to take advantage of the new methods of protection. The intent of the code makers is that Division and Zone classification not be mixed in a facility.

While the 1998 CEC brings Canada closer to a global system, it is not a completely harmonized. The US Zone system in the National Electrical Code is quite different to that of the CEC. Different ANSI product standards exist for the same methods of protection and the wiring methods are not complete. The CEC also accepts Division 2 practices in Zone 2, which are not permitted by CENELEC countries.

This article was intended as an overview to the changes to Sections 18 and 20. It is important that those involved with hazardous locations, review the new code and understand its impact on their business.

To assist Engineering Consultants, Plant Managers and Installers, Killark a division of Hubbell Electrical Products has released a 1998 Canadian Electrical Code Review and Application Guide. This publication written with the assistance of Vince Rowe, (Chairman of Section 18 CEC), Ken McLennan (Former Chief Electrical Inspector of Alberta) and Marty Cole (Chairman, Hazardous Location Products sub-section of EEMAC).

This Review is available to qualified designer, installers and inspectors.
To order this publication please email us here.