3/13/2018
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`Section 18 – Getting Familiar with Some New Terms | IAEI Magazine
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`Section 18 – Getting Familiar with Some New
`Terms
`
`By Leslie Stoch - January 16, 2007
`
`The 2006 Canadian Electrical Code, Section 18, Hazardous Locations, provides rules for
`installation and maintenance of wiring and electrical equipment in hazardous locations, and
`classification of areas that contain flammable or explosive gases, vapours or mists,
`combustible dusts or ignitable fibres. The 2006 CE Code introduces us to some brand new
`terms and has redefined some of the old ones. In this article, we will review a number of the
`Section 18 language changes and some new requirements.
`
`Rule 18-002 Special Terminology defines some of the special terms that appear throughout
`Section 18 that apply to explosive gas atmospheres. We need to understand the new terms
`and where they apply. Some of the more interesting changes involve sealing of conduits and
`cables.
`
`Cable Gland is a familiar term from the 2002 CE Code. A cable gland is a device used for the
`entry of cables or cords to provide strain relief at the points where they enter electrical
`equipment. It may also provide sealing to contain explosive gases, using an approved sealing
`compound within the cable gland.
`
`Cable Seal is a new term defined in Rule 18-002 as: “a seal that is installed at a cable
`termination to prevent the release of an explosion from an explosion-proof enclosure and that
`minimizes the passage of gases or vapours at atmospheric pressure.” Cable seals may be
`components of cable glands or in separate sealing fittings. Nothing is new here except for the
`redefinition of terms.
`
`Conduit Seal is also a new term defined as: “a seal that is installed in a conduit to prevent the
`passage of an explosion from one portion of the conduit system to another and that minimizes
`the passage of gases or vapours at atmospheric pressure.” Earlier versions of the code
`referred to “seals” without providing a more specific definition. Not much is new here either,
`except for a more precise definition.
`
`The 2002 CE Code, Rule 18-072 defined Explosive Fluid Seals as seals intended to prevent
`explosive fluids from reaching the electrical equipment and wiring. The 2006 CE Code has
`broadened the title and scope of Rule 18-072 to include both flammable gases and liquids.
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`Section 18 – Getting Familiar with Some New Terms | IAEI Magazine
`Flammable Gas or Liquid Seals has replaced the term Explosive Fluid Seals. Now Rule 18-072
`requires that: “Electrical equipment containing a seal intended to prevent flammable gases or
`liquids from reaching the housing or conduit system shall not be used at pressures in excess of
`the marked maximum working pressure (MWP).” Flammable gas or liquid seals are normally
`components of manufactured electrical equipment installed in high pressure containers or
`pipelines. Liquid seals are given a pressure test and assigned a maximum working pressure
`(MWP).
`
`Strangely, although the Rule 18-072 requirements refer to both flammable liquids and gases,
`the definitions of primary and secondary seals mention only the containment of process fluids.
`Similarly, the Section 18 rules for explosive gas atmospheres provide only a requirement for
`secondary seals only in the case of process fluids.
`
`Primary Seal is a new term, introduced for the first time in the 2006 CE Code. Rule 18-002
`defines a primary seal as: “a seal that isolates process fluids from an electrical system and has
`one side of the seal in contact with the process fluid.” A primary seal is usually a manufactured
`seal within an electrical device such as a flow switch installed in a high pressure piping
`system, to prevent process liquids from entering electrical conduit or equipment. A primary
`seal is one of the devices mentioned in Rule 18-072.
`
`Secondary Seal is yet another new term and it is defined as: “a seal that is designed to
`prevent the passage of process fluids at the pressure it will be subjected to upon failure of the
`primary seal”. In other words, a secondary seal provides backup in case the primary seal fails
`to contain process fluids. Secondary seals are required for sealing conduits and cables in Class
`I explosive gas atmospheres, where failure of a primary seal could allow flammable process
`fluids to leak into electrical equipment, with disastrous results.
`
`Secondary seals are always installed between the primary seals and the cable or conduit seals.
`Rule 18-072 requires that the MWP of the primary and secondary seals are never exceeded.
`Reason — the well-known conduit or cable seals are not designed to contain pressurized fluids
`and gases.
`
`As with past articles, you should contact the electrical inspection authority in each province or
`territory for a more precise interpretation of any of the above.
`
`Leslie Stoch
`https://iaeimagazine.org/magazine/2007/01/16/section-18-getting-familiar-with-some-new-terms/
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`3/13/2018
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`Section 18 – Getting Familiar with Some New Terms | IAEI Magazine
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`Leslie Stoch, P. Eng, is principal of L. Stoch & Associates, providing electrical engineering and ISO 9000 quality
`systems consulting. Prior to that, he spent over 20 years with Ontario Hydro as an electrical inspection
`manager and engineer. Les holds a B. S. in electrical engineering from Concordia University in Montreal.
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`https://iaeimagazine.org/magazine/2007/01/16/section-18-getting-familiar-with-some-new-terms/
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`Cooper Ex. 1015
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