(鍋爐, 下水道供人出入檢修用的)人孔, 檢修孔(A hole, usually with a cover, through which a person may enter a sewer, boiler, drain, or similar structure.)下水道出入孔:一種常帶有蓋的孔道,人可以由此孔進出排道、鍋爐、下水管、還有包括電人(鍋爐, 下水道供人出入檢修用的)人孔, 檢修孔(A hole, usually with a cover, through which a person may enter a sewer, boiler, drain, or similar structure.)下水道出入孔:一種常帶有蓋的孔道,人可以由此孔進出排道、鍋爐、下水管、還有包括電信、有線電視使用的弱電井,大型橋梁檢修用的內部通道等。