The CE Code is a comprehensive document. Sometimes it can seem quite daunting to quickly find the information you need. This series of articles provides a guide to help users find their way through this critical document. This is not intended to replace the notes in Appendix B or the explanations of individual requirements contained in the CEC Handbook, but will hopefully provide some help in navigating the Code.
Section 18, Hazardous locations, Part B. (The 24th Edition of the CEC, Part I, [C22.1-18] * is now available from CSA Group. This discussion of Section 18 is based on the new edition.)
Section 18 covers installation of electrical equipment in hazardous locations as defined in Section 0, such as areas in which there is a potential for the ignition of explosive or combustible gases, dusts, fibres, or flyings due to the design, installation, or use of electrical equipment. Becasue the information in this installment is extensive, it is presented in two parts. This installment is Part B. Part A appeared in the September/October issue of IAEI News.
Explosive gas atmospheres
This part contains rules for the installation of electrical equipment in all locations where explosive gas may be present.
Installations in Zone 0 locations
Rule 18-090 – Zone O is the hazardous location where explosive gas atmospheres are present continuously or for long periods and is the most restrictive. No electrical equipment or wiring may be installed in a Zone 0 hazardous location unless it is included in Table 18. Also note the marking requirements for Zone 0 (additional information is given in Appendices B and F).
Rule 18-092 – wiring methods in Zone 0 locations must be intrinsically safe. Where a cable is marked “HL” and contains one or more circuits that are not intrinsically safe, it may pass completely through a Zone 0 location providing there are no fittings or connections closer than 330 mm beyond the boundary and it is protected from mechanical damage by a raceway or similar means.
Rule 18-094 – seals are required where conduit leaves a Zone 0 location, and at the first point of termination of cables after entry to the Zone 0 location. Unbroken rigid conduit passing through a Zone 0 need not be sealed if the termination points are outside Zone 0. Seals are not required to be explosion-proof or flameproof “d” but must be identified as minimizing the passage of fluids or dusts and be accessible.
Installations in Zone 1 locations
Rule 18-100 – electrical equipment installed in a Zone 1 location must be in accordance with Table 18.
Rule 18-102 – rigid metal conduit, hazardous location cables, explosion proof or flameproof “d” boxes, and fittings with threaded connection to conduit and cable glands shall be used for wiring in Zone 1, and threads and joints need to be:
• tapered threads with at least 4-1/2 fully engaged threads with no running threads, or
• metric straight threads with a tolerance class 6g/6H and at least 5 full engaged threads,
except where intrinsically safe equipment and circuits are designed and installed as “ia”, “ib,” or intrinsically safe for Class I locations.
Rule 18-104 provides the rules for sealing conduits and cables entering enclosures in and leaving Zone 1 locations.
Rule 18-106 provides requirements for the installation of motors in Zone 1 locations. Additional guidance is given in Appendix B.
Rule 18-108 provides the rules for installation of luminaires in Zone 1.
Rule 18-110 – flexible cords are permitted in Zone 1 where flexibility is required between portable lamps or utilization equipment and the fixed supply, or for a portion of the circuit where a degree of movement is necessary for fixed and mobile electrical equipment, providing they:
• are extra hard usage type,
• contain a bonding conductor in addition to the insulated conductors,
• are provided with a sealing gland on entering a box, fitting, or enclosure that is flameproof “d”,
• are terminated with an increased safety “e” cord connector where entering an increased safety “e” enclosure, and
• are protected from damage by location or suitable guarding.
Installations in Zone 2 locations
Rule 18-150 provides the requirements for the installation of equipment in Zone 2 locations. Equipment in Zone 2 locations must be installed in accordance with Table 18. Also note other equipment as listed in Rule 18-150 (2) may also be installed in Zone 2 locations.
Rule 18-152 lists the wiring methods required for installations in Zone 2 locations.
Rule 18-154 provides the specifications for sealing conduit, cable and equipment in Zone 2 locations
Rule 18-156 provides requirements for installation of luminaires in Zone 2 locations.
Rule 18-158 – flexible cords are permitted in Zone 2 where flexibility is required between portable lamps or utilization equipment and the fixed supply, or for a portion of the circuit where a degree of movement is necessary for fixed and mobile electrical equipment providing they:
• are extra hard usage type,
• contain a bonding conductor in addition to the insulated conductors,
• are provided with a sealing gland on entering a box, fitting, or enclosure that is flameproof “d”, and
• are terminated with an increased safety “e” cord connector where entering an increased safety “e” enclosure.
Explosive dust atmospheres
This part contains rules for the installation of electrical equipment in all locations where combustible and explosive metal dust may be present.
Installations in Zone 20 locations
Rule 18-190 – like Zone O, Zone 20 is the most restrictive hazardous location where explosive dust atmospheres are present in the form of a cloud of dust in air continuously or for long periods. No electrical equipment or wiring may be installed in a Zone 20 hazardous location unless it meets the requirements of Table 18.
Rule 18-192 provides requirements for wiring methods in Zone 20 locations.
Rule 18-194 provides the specifications for seals for a Zone 20 location.
Rule 18-196 – flexible cords are permitted in Zone 20 where flexible connections are required and shall be extra-hard-usage cord with cable glands.
Installations in Zone 21 locations
Rule 18-200 provides rules for installation of equipment in Zone 21. Equipment in Zone 21 locations must be installed in accordance with Table 18.
Rule 18-202 lists the wiring methods required for installations in Zone 21 locations.
Rule 18-204 provides rules for sealing raceway equipment in Zone 21 locations.
Installations in Zone 22 locations
Rule 18-250 provides rules for installation of equipment in Zone 22. Equipment in Zone 22 locations must be installed in accordance with Table 18. This rule also provides rules for installation of cranes, hoists and other material handling equipment in Zone 22 locations.
Rule 18-252 provides rules for wiring methods in Zone 22 locations.
Rule 18-254 provides the same sealing requirements as Zone 21.
In the next installment, we will discuss Section 20 – flammable liquid and gasoline dispensing, service stations, garages, bulk storage plants, finishing processes, and aircraft hangars.
* The source for this series of articles is the Canadian Electrical Code, Part I, 24th Edition published by CSA, January 2018.
William (Bill) Burr is the former Chair of the Canadian Advisory Council on Electrical Safety (CACES), former Director of Electrical and Elevator Safety for the Province of BC, and former Director of Electrical and Gas Standards Development and former Director of Conformity Assessment at CSA Group. Bill can be reached at Burr and Associates Consulting, billburr@gmail.com