類型3S -- 防塵，防雨和防雹冰 -- 室外
　　Type 3S—Dust-tight, RaintightSleet Ice Proof—Outdoor
　　類型3S外殼適用于室外應用，保護殼內設備不受風塵和水的侵蝕，并在外殼覆蓋外層冰或雹的情況下，殼內設備仍然能夠運行。這些外殼并無法保護殼內設備免受由于內部結冰導致的故障。如果有這種要求，則應該咨詢儀器制造商。
　　Type 3S enclosures are intended for use outdoors to protect the enclosed equipment against windblown dustwaterto 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.

　　類型4 -- 防水和防塵 -- 室內
　　Type 4—WatertightDust-Tight—Indoor
　　類型4外殼適用于室內，用來保護殼內設備不受噴灑水的侵蝕，滲水，水瀑或軟管道流出的水，以及嚴重的外部凝結水的頁面。
　　Type 4 enclosures are intended for use indoors to protect the enclosed equipment against splashing water, seepage of water, falling or hose directed water,severe external condensation.

　　類型6 -- 可浸入水中，防水，防塵和防雹冰，室內和室外
　　Type 6—Submersible, Watertight, Dust-TightSleet Ice Resistant IndoorOutdoor
　　類型6外殼適用于偶爾會出現浸水情況的室內和室外應用。這種外殼應該保護殼內設備不受6英尺靜水壓持續30分鐘的侵蝕，不受灰塵、無腐蝕性液體的噴灑或外部凝結，水瀑或軟管流出的水，棉花和滲水的侵蝕。
　　Type 6 enclosures are intended for use indoorsout-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, lintseepage. They are not sleet ice proof.

　　類型7，類別1，組A, B, C, 和D空氣開關設備 -- 室內
　　Type 7, Class 1, Groups A, B, C, & D Air-Break Equipment—Indoor
　　類型7外殼適用于室內應用，在此環境和位置符合《美家電氣規程》中類別1，組A, B, C, 和D的定義。字母A, B, C, 或D表示在危險區域內的氣體或蒸汽環境，作為后綴加以指明。正如《美家電氣規程》中的定義，“類型7”提供完整的NEMA標志符號，分別符合類別1，組A, B, C, 或D。
　　Type 7 enclosures are intended for use indoors in the atmosphereslocations defined as Class IGroups A, B, C,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 designationcorrespond to Class 1, Group A, B, C, or D, respectively, as defined in the National Electrical Code.

　　類型9，類別11，組E, F, 和G空氣開關設備 -- 室內
　　Type 9, Class 11, Groups E, F, & G Air Break Equipment—Indoor
　　類型9外殼適用于室內，其環境符合《美家電氣規程》中有關類別11，組E,F, 或G的定義。字母E, F, 或G表示在危險區域內的灰塵環境，作為后綴加以標明。正如《美家電氣規程》的定義，“類型9”提供了完整的NEMA標志，分別符合類別11，組E, F, 或G。這些外殼防止有爆炸量的危險粉塵的進入。
　　Type 9 enclosures are intended for use indoors in the atmospheres defined as Class 11Groups 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 designationcorrespond 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.

　　危險環境的摘要信息根據《美家電氣規程》和UL
　　Summary of Hazardous Atmospheres Based on National Electrical CodeUL
　　在NEMA類型7和9定義中以加以說明。組用字母標明，標記在類性和類別之后，表示危險區域內的氣體或蒸汽環境。
　　As explained in the definitions of the NEMA Types 79. The groups indicated by letters, which follow the type class, indicate the gas or vapor atmospheres within the hazardous locations.
　　下列表格列出這些組包括的典型環境。
　　The following chart is a listing which gives the typical atmospheres covered by these groups.
　　您會注意到所列的環境在類別內包括“子類別1或2”。“子類別”清楚的表明所在區域是“通常是危險的”或是“異常時是危險的”。
　　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. 子類別1區域，通常是危險的。
   A Division 1 area, is or might be hazardous under normal conditions.
2. 子類別2區域，異常時是危險的。
   A Division 2 area, might become hazardous should an unusual condition arise.