Iec Final Second Year Questions And Answers With Latest Trials

What minimum size box (or box assembly) is required to contain the following? Exterior MC cable connectors are used on the cables. Two-10/2 with ground MC cables plus One- 12/2 with ground MC cable One- 30 amp 240-volt single receptacle and One- 20 amp 120- volt single receptacle {Ans: 4 x 2 1/8 square box with a 4.1 cu. in. two-gang plaster ring}Generally transformers have an efficiency of more than 90%. T/F {Ans: True}When a transformer is loaded beyond its rating the effects in the transformer are ______ -i. excessive temperature -ii. deterioration of insulation -iii. coil failure {Ans: i, ii and iii}______ in utility transmission lines reduces the power losses in the transmission conductors. {Ans: increasing the voltage}Where operating in the United States, AC voltage reaches a negative peak _____ times during one second. {Ans: 60}Your only available grounding electrode is the metal underground water pipe from the water utility. You are required by the NEC to have one other grounding electrode for your service. Which of the following driven electrodes could you use ? {Ans: 10 ft of trade size 1 rigid metal conduit}