120. PVC conduits can be buried on
A. lime
B. plaster
C. concrete
D. any of these.

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121. PVC conduits can be joined by
A. solvent cement
B. welding
C. threading
D. all of these

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122. The earthwire should not he thinner than a
A.aSW-G- wire
B. 16 SWG wire
C. 10 SWG wire
D. 8 SWG wire

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123. Electric braking is preferred because
A. smooth
B. maintenance cost is less
C. energy is saved in regenerating braking
D. all of these

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124. The various types of electric braking are
A. plugging
B. rheostatic braking
C. regenerative braking
D. all of these

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125. Braking retardation on suburban trains is
A. 0.3 to 0.5 km-phps
B. 0.5 to 1 km-phps
C. 3 to 5 km-phps
D. 30 to 40 km-phps

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126. The coefficient of adhesion is highest when the rails are
A. dry
B. oiled
C. wet with dew
D. dusty

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