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Killark Frequently Asked Questions (1997) Click here for newer Killark's faqs
Killark is a leading manufacturer of electrical products for use in hazardous locations. Our product offering includes both traditional and IEC Zone equipment for North America and global products with CENELEC approval for use around the world. Killark is also very active in the area of Codes and Standards for hazardous (classified) locations in North America. We at Killark pride ourselves on our knowledge and ability to assist our customers in these areas.
The following are some of the more frequently asked questions;
Q. What is a hazardous location?
A. Hazardous locations are defined by the Canadian Electrical Code (CEC) Section 18 and the National Electrical Code (NEC) as those areas in which the potential for fire or explosion exists due to the presence of flammable gases or vapours, combustible dusts and easily ignited fibres or flyings.
Q. Why do I see the term "hazardous (classified) location" used from time to time?
A. This is a term used in the United States only. As we understand it, the term "hazardous" caused some concern over liability. It was felt, by adding the term "classified", and perhaps removing the term "hazardous" eventually, the reference would be less of a concern.
Q. The world is full of hazardous materials are they all explosive?
A. No, the hazardous materials we refer to in the electrical code are those when mixed with air can cause an explosion or fire.
Q. What do Class, Divisions and Groups mean?
A. Classes refer to the type of hazard present in an area. Class I, is flammable gases and vapours, Class II, is combustible or electrically conductive dusts, and Class III, is easily ignited fibres or flyings.
Divisions refer to the conditions, frequency or duration a explosive or flammable substance is present.
Division 1 indicate that a facility, which is operating within its’ design parameters, has explosive gas or dust mixtures present periodically, intermittently or for long periods of time. In other words, it is the normal condition the hazard to be present.
Division 2 indicates that the explosive or flammable material, while it is still present, is normally confined in enclosed systems or containers and will only be in the atmosphere if the system is operated incorrectly or containers are accidentally ruptured. This condition is abnormal and the substance is only present for short periods of time. Division 2 locations are also immediately adjacent to Division 1 locations.
In very basic terms, Groups relate to the explosive pressures and flame temperatures generated by a substance and the minimum gap through which an explosion can travel. Gas Groups are A, B, C, and D. Dust Groups are E, F and G. Class III has no Groups.
Q. What are Fibres and Flyings
A. Fibres and Flyings relate to materials such as cotton fibres, flax and other textile materials and lint. In sufficient quantities, a flash fire can start with these materials which is very dangerous and similar to an explosion.
Q. If I have an explosive substance in my facility is there always the risk of an explosion.
A. For an explosion to occur, three things must be present; fuel ( the explosive or flammable material), oxygen or air, and an ignition source. The chance of an explosion depends on the mixture of air and fuel and the presence of an heat source hot enough to ignite the material. All explosive or flammable materials have a lower and upper flammable range, too lean or too rich and nothing will happen
Q. What is a Temperature or "T" Code and does it have anything to do with Class, Division and Group.
A. The Temperature Code, or T Code as it is commonly referred to, relates to the temperature at which a substance will ignite without a spark or flame. (Something like a heater or lamp while it doesn’t have a flame can be hot enough to set off an explosion).
Q. If I have a hazardous location do I always need explosion proof equipment?
A. No. The type of equipment used is depends on the Class, Division, Group, and Temperature Code of the area. Given this information, a manufacturer, such as Killark, can offer the right equipment for the job.
Q. I understand the electrical codes are changing to have Zones instead of Divisions. What does this mean.
A. Zones were added to the 1996 NEC and will be added to the 1998 CEC. Zones deal with explosive or flammable gases only. Instead of two divisions, hazardous locations are divided into three Zones
The chart below identifies how the two compare.
Comparison of 1998 CEC and Pervious Versions of CEC for Hazardous Locations
Definitions (the 1996 NEC is similar to the 1998 CEC)
| Class | Nature of Hazard | 1998 CEC | Previous CECVersions | NOTES |
| I | Gases and Vapours | Zone 0
Zone 1 |
1 | The term Zone is used in place of Division to limit confusion and is the same term used in the IEC method. The combination of Zones 0 & 1 is essentially the same as Division 1. |
| Zone 2 | 2 | Zone 2 and Division 2 are essentially the same. | ||
| II | Combustible Dusts | 1
2 |
No Changes to Class II & III | No changes were made to this section of the code |
| III | Easily Ignitable Fibres and Flying | 1
2 |
| Typical Gas | Traditional Gas Group | 1998 CEC and IEC Gas Group |
| Acetylene | A | II C |
| Hydrogen | B | |
| Ethylene | C | II B |
| Propane | D | II A |
A. The introduction of the International Electrotechnical Commission’s (IEC) three Zone area classification method increases the types of methods of protection available for equipment and wiring systems.
Q. Do I have to change all my existing equipment if I switch to Zones?
A. No, the move to Zones permits the use of traditional Class and Division equipment. However, the intent in both Canada and the US is that facilities must be re-classified prior to using IEC type equipment in Zone 0 or 1 locations.
Q. How do I learn more about Zones and the IEC?
A. For your convenience,
Killark has published an article on the Internet on the subject.
Click here
for more information from Killark.
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