求翻译：6． PVC管安装好后，统一穿电线，同一回路电线应穿入同一根管内，但管内总根数不应超过8根，电线总截面积（包括绝缘外皮）不应超过管内截面积的40％。是什么意思？

6. After the installation of PVC pipe, uniform to wear a wire, the same circuit wires should be put into the same root canals, but tubes total number should not exceed 8 root, wire the total cross-sectional area (including the insulation jacketing) should not exceed pipe cross-sectional area of 40%.