COD, if used as a cable duct, should be laid in accordance with all items prescribed in the Electrical Equipment Technique standard and all other applicable laws and regulations. At the construction site, therefore, COD should be laid in accordance with the standardized laying procedures described below.
The number of laid COD determines the trenching width. However, the width should be determined with due consideration of economy and safety associated with the laying operation; it is required to carry out maximum of safety procedures so that no landslide is caused at the minimum of width. The lowermost COD should not be laid directly on rocks and sharp pebbles. It is recommended that the excavated area should be leveled and then covered with sand or soft soil before laying COD.
COD should be laid carefully so as to prevent soil, sand and water from entering COD through the end mouth. If coiled COD delivered to the site, it should be laid in accordance with the following procedure. The coiled COD should be uncoiled along the trenched ground, being held by laborers so that it is well laid inside of the trench. Make it sure to uncoiling is stretched straight.
When 2 or more COD are to be laid in parallel, the respective COD should be arranged with the specified distance as shown in Fig. A. To this end, a simple gauge shown in Fig. B should be prepared to straighten the laid COD every 3 or 4 meters. The straightened COD should be held in place with sand or the equivalent, and then the gauge should be removed. COD should not be laid on pipe saddles, which have been used for conventional Hume pipe.
For economical operation, particularly where paving is involved, the trench dimension should be no greater than the specified dimension. Generally, 0.2 m(W) x 0.5(H) dimension is recommended up to laying of 2 lines of COD regardless of numbers of inner ducts.
If not specified in specifications, mechanical leveling of the trench bed by excavator will be sufficient.
After the trench is being excavated, either release-and-place the COD on the ground surface along with the trench to put it into such trench or lay directly into the trench by releasing the COD from the spool. To carry out backfill according to the job specifications after required connection being properly made on the ground surface.