A cable tray includes first and second opposite tray walls and at least one divider arrangement between the tray walls. The divider arrangement includes first and second divider walls joined to each other with a cooling volume between them. A first cable channel is defined between the first tray wall and the first divider wall. A second cable channel is spaced from the first cable channel by the cooling volume and is defined between the second divider wall and at least one of the second tray wall or an additional divider wall. The tray can be used in methods of laying cable. The tray can be part of a ladder rack.