Well, after finding out that the zinc alloy nail-in anchors are not supposed to be used for anchoring to ceilings (because of the low fusing tmeperature), it just made sense to me to have the same prohibition for plastic anchors. Yet, I haven't found any literature to that effect. Recently I removed some stem hung 2 tube 8 ft fixtures, and they were fastened to the concrete with plastic anchors, and it just seemed too flimsy, especially because of the increased dynamic load due to the 3 ft long stems.
