{"id":21276,"date":"2021-07-01T08:58:38","date_gmt":"2021-07-01T13:58:38","guid":{"rendered":"https:\/\/iaeimagazine.org\/?p=21276"},"modified":"2022-05-31T16:07:45","modified_gmt":"2022-05-31T21:07:45","slug":"classification-of-hazardous-locations","status":"publish","type":"post","link":"https:\/\/iaeimagazine.org\/issue\/july-august-2021\/classification-of-hazardous-locations\/","title":{"rendered":"Classification of Hazardous Locations"},"content":{"rendered":"

Some of the most intimidating work that an authority having jurisdiction (AHJ) can encounter involves hazardous (classified)<\/em> locations and what classification those areas will carry.\u00a0 It is critical that this be completed properly in order to assure the safety of the property and the public.\u00a0 The equipment used in a hazardous (classified)<\/em> location is not cheap!\u00a0 With that being said, honesty from everyone associated with this project concerning what will be occurring, stored, or produced in these areas is very important.<\/p>\n

The Fire Triangle<\/h2>\n

To develop an understanding of the hazards associated with the use of electricity in hazardous (classified)<\/em> locations, a review of the components (oxygen, heat or ignition, and fuel) of the fire triangle is in order.\u00a0 All three elements of the triangle must be present in specific ratios for ignition and explosion to occur (see figure 1). Vapor density will impact the likelihood that an ignitible concentration will develop (see figures 2, 3, 4, and 5).<\/p>\n

\"Figure<\/a>
Figure 1.<\/strong> Components necessary for an explosion if all conditions are correct.<\/figcaption><\/figure>\n
\"Figure<\/a>
Figure 2.<\/strong> Only the fuel source is present (no explosion).<\/figcaption><\/figure>\n
\"Figure<\/a>
Figure 3.<\/strong> Only the fuel and air (oxygen) source are present (no explosion).<\/figcaption><\/figure>\n
\"Figure<\/a>
Figure 4.<\/strong> Fuel, air (oxygen), and ignition source present (but not in correct mixture-no explosion).<\/figcaption><\/figure>\n
\"Figure<\/a>
Figure 5.<\/strong> Fuel, air (oxygen), and ignition source present in correct mixture- explosion.<\/figcaption><\/figure>\n

The heat or ignition source is the electrical system, although it could also be an open flame or other heat sources that exceed the ignition levels of the materials involved. The fuel leg of the triangle could be one or a combination of the various materials listed in the tables provided in NFPA 497\u20132017<\/em>, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas<\/em> or NFPA 499\u20132017, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.<\/em><\/p>\n

Requirements in standards related to hazardous (classified)<\/em> locations are based on normal atmospheric quantities of oxygen. It should be noted that these standard requirements have not considered situations involving oxygen-enriched or oxygen-deprived atmospheres. Identifying those conditions is part of the risk assessment and analysis process when determining area classification.<\/p>\n

The range of flammability needs to be considered when assessing area classifications.\u00a0 Not all fuel types are as volatile and must be considered individually.\u00a0 Take methane, for instance.\u00a0 The lower explosive limit (LEL) is 5, and the upper explosive limit (UEL) is 15.\u00a0 On a scale provided in figure 6, there is a specific range in which conditions exist for there to be a possibility of an explosion (between 5 and 15).\u00a0 Now consider another item such as hydrogen.\u00a0 It has an LEL of 4 and a UEL of 75.\u00a0 Hydrogen has a much broader flammability range where conditions exist for a possible explosion (between 4 and 75).<\/p>\n

\"Figure<\/a>
Figure 6.<\/strong> The flammability scale showing the range of flammability for certain items.<\/figcaption><\/figure>\n

The Assessment Team<\/h2>\n

Area classification can be a very daunting task.\u00a0 It is not the responsibility of the AHJ to determine the classification of an area.\u00a0 The AHJ should not be determining the area classification as a \u201clone wolf.\u201d\u00a0 The assessment should be conducted by a team of experts that bring various talents to the table (see figure 7). The AHJ may be part of this team but should be approving and enforcing Code<\/em> rules to that classified area once the assessment team determines what that classification will be.<\/p>\n

\"Figure<\/a>
Figure 7.<\/strong> Utilize a team to assess the area, and then the AHJ approves their recommendations.<\/figcaption><\/figure>\n

It is critical that full disclosure by the engineer or building owner is made about a particular building or area.\u00a0 Most are aware that specialized equipment is utilized in these classified areas and that this equipment will be much more expensive than ordinary electrical equipment.\u00a0 Being deceitful to save a few dollars put the structure and the public at serious risk if the right conditions present themselves.<\/p>\n

Members of the assessment team should work together to determine the area classification. By using their knowledge and experience, the assessment should follow what some would consider a reverse NCAA basketball tournament bracket.\u00a0 Instead of working down to an eventual champion, the assessment team starts at the championship position and moves backward through the bracket (see figures 8, 9, and 10).\u00a0 Each level presents a particular question for the assessment team to consider.<\/p>\n

\"Figure<\/a>
Figure 8.<\/strong> The assessment team begins to consider the area and what is present.<\/figcaption><\/figure>\n
\"Figure<\/a>
Figure 9.<\/strong> The assessment team considers if they are dealing with a gas\/vapor or a combustible dust.<\/figcaption><\/figure>\n
\"Figure<\/a>
Figure 10.<\/strong> Assessment team determines a gas\/vapor environment and now considers if \u201calways present\u201d or \u201cnot normally present.\u201d<\/figcaption><\/figure>\n

In our example shown in the figures, one of the first steps is to determine if they are dealing with a Class I (gas\/vapor environment) or a Class II (combustible dust) environment.\u00a0 Based on their findings, the assessment team moves up the bracket to the next decision point.\u00a0 In our example, the assessment team decided they were presented with a Class I (gas\/vapor) environment.\u00a0 Now the team needs to consider if the gas\/vapor is \u201calways present\u201d or \u201cnot normally present.\u201d\u00a0 They move the team to that position of the bracket and then solve other decision points until they have completed the area classification.\u00a0 The findings are then presented to the AHJ for his\/her review and approval.\u00a0\u00a0 This technique can be applied to all types of potentially hazardous (classified) <\/em>locations to make area assessments.<\/p>\n

\"Figure<\/a>
Figure 11.<\/strong> IAEI\u2019s Hazardous Locations book updated to the 2017 National Electrical Code (NEC).<\/figcaption><\/figure>\n

Safety Starts with You<\/h2>\n

This is a small part of working with hazardous (classified) locations.\u00a0 Many electricians and inspectors will never be involved in these environments.\u00a0 In some cases, the inspector might be involved with a local fuel station being constructed in their jurisdiction.\u00a0\u00a0 In many of these cases, the electrical contractor used by the owner of the fuel station may specialize in this type of work.\u00a0 If this is the case, the electrical contractor will know a lot about the \u201cdos and don\u2019ts\u201d associated with this environment.<\/p>\n

If you want to know more information about hazardous (classified)<\/em> locations, please consider the IAEI\u2019s book Hazardous Locations<\/em> as part of your library (see figure 11).\u00a0 You can also go to the IAEI website at iaei.org and view several short on-demand training events that will help with your understanding of this specialized electrical topic.<\/p>\n

As always, safety starts with you.\u00a0 Your attitude and work ethic are important in the quest of continuing the legacy of keeping families electrically safe.\u00a0 When it comes down to it, we are all members of a family.\u00a0 I hope all of you consider the IAEI as part of your electrical professionals\u2019 family.<\/p>\n","protected":false},"excerpt":{"rendered":"

Some of the most intimidating work that an authority having jurisdiction (AHJ) can encounter involves hazardous (classified) locations and what classification those areas will carry. <\/p>\n","protected":false},"author":282,"featured_media":21288,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[23083,22985],"tags":[23133,22986,328],"class_list":{"0":"post-21276","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-electrical-fundamentals","8":"category-july-august-2021","9":"tag-hazardous-locations","10":"tag-july-august-2021","11":"tag-zone-classification"},"_links":{"self":[{"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/posts\/21276","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/users\/282"}],"replies":[{"embeddable":true,"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/comments?post=21276"}],"version-history":[{"count":1,"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/posts\/21276\/revisions"}],"predecessor-version":[{"id":21289,"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/posts\/21276\/revisions\/21289"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/media\/21288"}],"wp:attachment":[{"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/media?parent=21276"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/categories?post=21276"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/iaeimagazine.org\/wp-json\/wp\/v2\/tags?post=21276"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}