NEMA区域分级NEMA Area Classification

　　类型3S -- 防尘，防雨和防雹(冰) -- 室外
　　Type 3S—Dust-tight, Raintight and Sleet (Ice) Proof—Outdoor
　　类型3S外壳适用于室外应用，保护壳内设备不受风尘和水的侵蚀，并在外壳覆盖外层冰或雹的情况下，壳内设备仍然能够运行。这些外壳并无法保护壳内设备免受由于内部结冰导致的故障。如果有这种要求，则应该咨询仪器制造商。
　　Type 3S enclosures are intended for use outdoors to protect the enclosed equipment against windblown dust and water and to provide for its operation when the enclosure is covered by external ice or sleet. These enclosures do not protect the enclosed equipment against malfunction resulting from internal icing; where this is a requirement, the apparatus manufacturer should be consulted.

　　类型4 -- 防水和防尘 -- 室内
　　Type 4—Watertight and Dust-Tight—Indoor
　　类型4外壳适用于室内，用来保护壳内设备不受喷洒水的侵蚀，渗水，水瀑或软管道流出的水，以及严重的外部凝结水的页面。
　　Type 4 enclosures are intended for use indoors to protect the enclosed equipment against splashing water, seepage of water, falling or hose directed water, and severe external condensation.

　　类型6 -- 可浸入水中，防水，防尘和防雹(冰)，室内和室外
　　Type 6—Submersible, Watertight, Dust-Tight and Sleet (Ice) Resistant Indoor and Outdoor
　　类型6外壳适用于偶尔会出现浸水情况的室内和室外应用。这种外壳应该保护壳内设备不受6英尺静水压持续30分钟的侵蚀，不受灰尘、无腐蚀性液体的喷洒或外部凝结，水瀑或软管流出的水，棉花和渗水的侵蚀。
　　Type 6 enclosures are intended for use indoors and out-doors where occasional submersion is encountered. They shall protect the enclosed equipment against a static head of water of six (6) feet for thirty (30) minutes, dust, splashing or external condensation of noncorrosive liquids, falling or hose directed water, lint and seepage. They are not sleet (ice) proof.

　　类型7，类别1，组A, B, C, 和D空气开关设备 -- 室内
　　Type 7, Class 1, Groups A, B, C, & D Air-Break Equipment—Indoor
　　类型7外壳适用于室内应用，在此环境和位置符合《美国电气规程》中类别1，组A, B, C, 和D的定义。字母A, B, C, 或D表示在危险区域内的气体或蒸汽环境，作为后缀加以指明。正如《美国电气规程》中的定义，“类型7”提供完整的NEMA标志符号，分别符合类别1，组A, B, C, 或D。
　　Type 7 enclosures are intended for use indoors in the atmospheres and locations defined as Class I and Groups A, B, C, and D in the National Electrical Code. The letters A, B, C, or D which indicate the gas or vapor atmospheres in the hazardous location appear as a suffix to the designation, “Type 7” to give the complete NEMA designation and correspond to Class 1, Group A, B, C, or D, respectively, as defined in the National Electrical Code.

　　类型9，类别11，组E, F, 和G空气开关设备 -- 室内
　　Type 9, Class 11, Groups E, F, & G Air Break Equipment—Indoor
　　类型9外壳适用于室内，其环境符合《美国电气规程》中有关类别11，组E,F, 或G的定义。字母E, F, 或G表示在危险区域内的灰尘环境，作为后缀加以标明。正如《美国电气规程》的定义，“类型9”提供了完整的NEMA标志，分别符合类别11，组E, F, 或G。这些外壳防止具有量的危险粉尘的进入。
　　Type 9 enclosures are intended for use indoors in the atmospheres defined as Class 11 and Groups E, F, or G in the National Electrical Code. The letters E, F, or G which indicate the dust atmospheres in the hazardous location appear as a suffix to the designation “Type 9” to give the complete NEMA designation and correspond to Class 11, Group E, F, or G, respectively, as defined in the National Electrical Code. These enclosures prevent the ingress of explosive amounts of hazardous dust.

　　危险环境的摘要信息(根据《美国电气规程》和UL)
　　Summary of Hazardous Atmospheres (Based on National Electrical Code and UL)
　　在NEMA类型7和9定义中以加以说明。组(用字母标明)，标记在类性和类别之后，表示危险区域内的气体或蒸汽环境。
　　As explained in the definitions of the NEMA Types 7 and 9. The groups (indicated by letters), which follow the type class, indicate the gas or vapor atmospheres within the hazardous locations.
　　下列表格列出这些组包括的典型环境。
　　The following chart is a listing which gives the typical atmospheres covered by these groups.
　　您会注意到所列的环境在类别内包括“子类别1或2”。“子类别”清楚的表明所在区域是“通常是危险的”或是“异常时是危险的”。
　　You will note that this list also includes a “Division 1 or 2” in addition to the class. The “Division” simply indicates if the area in question is considered “Normally Hazardous” or “Not Normally Hazardous.”

1. 子类别1区域，通常是危险的。
   A Division 1 area, is or might be hazardous under normal conditions.
2. 子类别2区域，异常时是危险的。
   A Division 2 area, might become hazardous should an unusual condition arise.