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61.
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What is the MINIMUM size THWN copper conductors required to supply a continuous-duty, 25 hp, 208-volt, 3-phase motor, where the motor is on the end of a short conduit run that contains only three (3) conductors, and located where exposed to an ambient temperature of 115 deg. F?
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To determine the minimum size required of the conductors to supply this motor, first find the full-load current rating of the motor, 74.8 amperes, from Table 430.250. Next, as per Section 430.22 multiply by 125%. Then, divide by the temperature correction factor, 0.75, from Table 310.15(B)(2)(a). Finally, select the conductor size, 1 AWG THWN, from Table 310.15(B)(16).
25 hp motor FLC = 74.8 amperes x 125% = 93.5 amperes 93.5 amps .75 (temperature correction) = 124.6 amperes
*NOTE: The wire size needs to be increased because of the elevated ambient temperature. Size 1 AWG THWN conductors with an allowable ampacity of 130 amperes should be selected.
Incorrect answer. Please choose another answer.
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72.
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Determine the MINIMUM size THWN copper branch-circuit conductors required by the NEC® to supply one 40 hp, 480 volt, continuous duty, 3-phase, induction-type, Design C, motor.
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To determine the minimum conductor size to supply this motor, first locate the full-load current rating of the motor, 52 amperes, from Table 430.250. Next, as per Section 430.22 multiply this value by 125%. Then, select the conductor size, 6 AWG THWN, from Table 310.15(B)(16). 40 hp FLC = 52 amperes x 125% = 65 amperes
Incorrect answer. Please choose another answer.
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