What is the horizontal separation, in well tamped earth, required between power and direct buried telecommunications facilities sharing the same trench?

152mm (6 in) is insufficient and does not meet the minimum horizontal separation required by BICSI or NEC for shared power and telecom trenches.

229mm (9 in) falls below the 300mm minimum threshold and would not satisfy code requirements for this shared-trench scenario.

When power and direct-buried telecommunications facilities must share a trench, BICSI OSP standards specify 300mm (12 in) as the required horizontal separation in well-tamped earth. Well-tamped earth provides a consistent physical barrier that justifies this specific distance, which is a standardized minimum to reduce inductive interference and physical damage risk between the two cable types.

381mm (15 in) exceeds the required minimum for well-tamped earth and is not the specified standard distance for this condition.

457mm (18 in) may apply to other installation conditions such as loose earth, but it exceeds the minimum required specifically for well-tamped earth.