I came across the below scenario and wondered what everyone thought of it.
An industrial site with multiple layers of tray running horizontally over external open ground. Different trays contain power and communications cables. Power cables are armoured. The tray and horizontal supports are bonded back to the MET, however, the metal vertical stanchions of the tray support system are not bonded but are electrically isolated from the tray work (by plastic washers) - I'm told this is a requirement of the communications engineer. The stanchions are fixed to a concrete base.