Which of the following is an NEC Article 427 requirement for the installation of electrical heat-tracing cables on pipe and vessels in unclassified areas?
a. The external surfaces of any equipment that operates at temperatures above 100°F (38°C)
must be physically guarded, isolated, or thermally protected.
b. Branch circuits and overcurrent devices supplying the equipment must be sized at no less
than 100 percent of the total heater load.
c. The heating cable cannot be allowed to make direct contact with the pipe or vessel.
d. The presence of electric heating equipment must be identified using permanent caution
signs or markings at the specified intervals.
d. The presence of electric heating equipment must be identified using permanent caution
signs or markings at the specified intervals.
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Connecting a 120V heating cable to a 240V circuit will _____.
a. melt the cable b. produce only 25% of the rated cable wattage c. cause the system to operate within acceptable standards, but at less than full efficiency d. enable the system to operate most efficiently
A rigid vessel initially contains saturated steam at P = 0.2 MPa. Heat is added until the pressure is 0.3 MPa. Determine the amount of heat added per kilogram of steam, and the change in specific entropy of the gas.
A. 3963 kJ/kg and 0.5751 kJ/kg•K B. 277 kJ/kg and 0.5751 kJ/kg•K C. 287 kJ/kg and 0.5971 kJ/kg•K D. 14.1 kJ/kg and 0.5971 kJ/kg•K E. Insufficient information to solve
The flanges of a wood I-beam may be made of laminated veneer lumber or specially selected ____-jointed solid wood lumber.
a.double c.reciprocally b.finger d.toe
The machine spindle is centered over an existing hole in the workpiece with the aid of:
A) An edge finder B) A precision rule C) A dial indicator D) All of the above