Power cable distance from sensor cables

[bigone001]

I am about to dig a trench to lay the cables to a liftmaster gate motor. The mains cable is armoured, and the cables from the sensors are in a seperate conduit. How much physical separation is needed in the trench between the low voltage and high voltage cables? Is six inches of soil and the separate conduits sufficient to avoid problems ?
At some point the cables come together where they enter the liftmaster box, and there physical separation is almost impossible.
Thanks for your help

[Mark]

The Rule of Thumb for electrics is usually 30cm or 12 inch but the 6 inch inside conduit should be fine