| 摘要 |
An electric cable and/or service pipe support comprises an elongate metal duct (1) divided transversely of its length into at least two separately formed parts that are detachably secured together and, housed in the duct, metal means (2) for supporting at least one electric cable and/or service pipe. At least one part of the duct has at spaced positions along its length, for cooling purposes, ventilation holes (11) for passage of air into and out of the duct. A plurality of separately operable ventilation hole-closure devices (4) are mounted in and arranged at spaced positions along the length of the duct, each adapted to close automatically a group of ventilation holes when the temperature outside the duct reaches or exceeds a predetermined value. Preferably, each ventilation hole-closure device (4) is a flat plate normally supported in such a position with respect to the ventilation holes that air can flow into and out of the duct but which, when automatically operated, moves in such a direction and to such an extent as to close the ventilation holes.
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