The standard radius of any bend in conduit, whether manufactured, or set by hand or machine, should not be less than that given in the table in, and no cables should be drawn around conduit bends of less radius then this. Methods of Installation Conduit Wiring Two methods are generally used when installing conduit. These are the surface system and the concealed system. It depends on the type and condition of installation as to which system should be used. Generally the surface system should be used in factories, warehouses, commercial buildings, etc. where the sight of exposed runs of conduit is not important. However, in buildings such as offices or houses, appearance is essential and so the concealed conduit system should be used.
Although heavy gauge conduit gives very good mechanical protection to cables in some factory or commercial installations it is possible for surface conduit to be damaged if hit by heave objects such as cranes, lorries, fork lift trucks etc. This can often be prevented by re-routing the conduit behind a girder, or screening it with sheet steel, but if this is not possible or there is danger of frequent injury, the conduit should be concealed. Conduit should also be run concealed where there is excessive moisture or chemical fumes.
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