1, For a solid wall, floor or ceiling, the above required depth may be reduced to 25mm for lengths of conduit which are within 4m of a visible accessory or connection point, or where the circuits contained in the conduit are protected by a 30mA RCD.
(我主要是纠结于 of a visible accessory or connection point)
2,Cable trunking and cable tray shall be run exposed or otherwise accessible after installation, throughout its length, for the purpose of removing or installating cable.(我理解的是:电缆线槽和桥架应当敞开运行,但是根据相关技术人员的了解,电缆线槽和桥架都是要加盖盖板的,所以比较迷糊)
3,Where plastic conduit is installed outdoors, it should be suitable for exposure to solar radiation.
参考资料:ogin_u