Aweatherproof metal junction box measuring 4 m. × 4 m. × 6 in, has been installed to support a luminaire. two rigid metal conduits have been threaded wrenchtight into the threaded entries of the enclosure. the box has not yet been secured to the brick wall. but both conduits have been strapped to the wall 16 in. from the box. what additional support (from the following list) is required for this box? 1. two metal screws with plastic anchons il. two toggle bolts ih. two drive pins

a) none
b) i or il only
c) i or ill only
d) i. ii, or iii 10.

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.