封闭母(mu)(mu)线(xian)(xian)槽(cao)（简称母(mu)(mu)线(xian)(xian)槽(cao)）是由金属(shu)板（钢板或(huo)铝板）为保护外(wai)壳、导(dao)电排、绝缘材料及(ji)有(you)关附件(jian)组成的母(mu)(mu)线(xian)(xian)系统。它可制成每隔一段距离(li)设有(you)插接分(fen)(fen)线(xian)(xian)盒(he)的插接型封闭母(mu)(mu)线(xian)(xian)槽(cao)，也(ye)可制成中间不带分(fen)(fen)线(xian)(xian)盒(he)的馈电型封闭母(mu)(mu)线(xian)(xian)槽(cao)。在高层建筑(zhu)的供(gong)电系统中，动力(li)和(he)照明线(xian)(xian)路往(wang)往(wang)分(fen)(fen)开设置，母(mu)(mu)线(xian)(xian)槽(cao)作为供(gong)电主干线(xian)(xian)在电气竖井内沿(yan)墙(qiang)垂直安装(zhuang)一趟或(huo)多趟。
按用途一趟母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)槽(cao)一般由始(shi)端母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)槽(cao)、直通(tong)母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)槽(cao)（分带插(cha)孔和不(bu)带插(cha)孔两种）、L型垂直（水平）弯通(tong)母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)、Z型垂直（水平）偏(pian)置母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)、T型垂直（水平）三通(tong)母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)、X型垂直（水平）四(si)通(tong)母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)、变容母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)槽(cao)、膨胀(zhang)母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)槽(cao)、母(mu)(mu)线(xian)(xian)(xian)(xian)(xian)槽(cao)有(you)关(guan)附件及紧固装置等(deng)组成。
封闭式母线安装场(chang)地(di)不(bu)(bu)易(yi)超过(guo)(guo)海拔(ba)高(gao)度2000m，周围(wei)空气(qi)(qi)温度不(bu)(bu)高(gao)于+40℃、不(bu)(bu)低于－5℃，在(zai)(zai)24小(xiao)时内其品平均(jun)温度不(bu)(bu)超过(guo)(guo)+35℃，空气(qi)(qi)相对湿(shi)度在(zai)(zai)40℃时不(bu)(bu)超过(guo)(guo)50%、在(zai)(zai)20℃时不(bu)(bu)超过(guo)(guo)90%。周围(wei)空气(qi)(qi)清洁无尘埃及腐(fu)蚀绝缘的气(qi)(qi)体(ti)。