CEC table D17 Conditions

A suggestion:
Tables D17A through D17l have to do with buried cables.
Only tables D17M and D17N have to do with cable tray installations.
The primary intent of section D is to give the ampacity of various methods of cable installation, mostly buried.
I suggest that the intent of the 3 meter note is that buried circuits must be separated by 3 meters for safety.
In the event of an underground fault that must be repaired, you don't want to inadvertently dig into an adjacent circuit.
Consider yourself faced with the task of exposing and repairing a fault in a 5 kV buried circuit immediately adjacent to a buried 46 kV circuit.
During a lifetime in the field I have never seen a 3 meter separation applied to cable tray installations.
But to CYA (Cover Your Assets), check with the AHJ (Authority Having Jurisdiction).

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Ohm's law
Not just a good idea;
It's the LAW!

Canadian Electric Code Appendix D Table D17M and N Ampacity for single cable tray no more than 3 cables.
However, in NEC art. 392.18 Cable Tray Installation.
(F) Adequate Access. Sufficient space shall be provided and maintained about cable trays to permit adequate access for installing and maintaining the cables.
DIN VDE 276-1000 up to 6 cable trays in one column and up to 3 groups of 3 cables in a tray keeping 300 mm vertical clearance.
IEC 60346-5-52 up to 3 cable trays in a column 300 mm vertical clearance up to 3 groups of 3 cables per one tray.
IEEE 525/2007 IEEE Guide for the Design and Installation of Cable Systems in Substations
E.3.2 Tray system design
a) In general, vertical spacing for cable trays should be 30 cm (12 in), measured from the bottom of
the upper tray to the top of the lower tray. A minimum clearance of 23 cm (9 in) should be
maintained between the top of a tray and beams, piping, etc., to facilitate installation of cables in the tray.