Can anyone advise me where I can find a complete description of what depth cables must be laid at and at what depth the marker tape should be added, thank you

Try this link http://www.njug.org.uk/w...s-Issue-4-29-10-2013.pdf I don't think there is any depths given for the marker tape. However if the the depth of the utility allows it, I would suggest that you put it at 300mm to 500mm deep as this would be inline with HSG47 guidance for 'power tools and excavators'.

Latchy Cable depth is dependant upon a number of factors; 1. the cable voltage 2. ground condictions 3. where it is buried - in a road, farmers field, under existing features (rail line) etc The designer needs to design the entire cable route taking these into account. As an example we have 400,000HVDC cables buried in Ireland & Wales, depth of cable duct varies between 1 meter (min) with marker boards at 600mm and tape at 400mm (from surface) to a depth of 4.5 meters under a railway.