Final Answer:
The suitable Liquid Tight Flexible Metal conduit size for three No. 3 T90 NYLON and two No. 8 T90 NYLON conductors would be trade size 41 (1 ½"). Thus, the correct answer is option c- trade size 41 (1 ½").
Step-by-step explanation:
To determine the suitable conduit size, we follow the guidelines provided by the National Electrical Code (NEC). Firstly, we identify the conductor sizes and count: three No. 3 T90 NYLON conductors and two No. 8 T90 NYLON conductors. The NEC provides tables specifying the allowable fill capacities for different conduit sizes and conductor combinations.
Next, we calculate the total cross-sectional area of the conductors. The cross-sectional area is crucial for determining the fill capacity of the conduit. For instance, the cross-sectional area of each conductor is calculated using the formula for the area of a circle (A = π * r²), where "r" is the radius of the conductor. The sum of the cross-sectional areas of the three No. 3 conductors and two No. 8 conductors is compared with the allowable fill capacity for different conduit sizes.
Finally, we select a conduit size that accommodates the calculated total cross-sectional area without exceeding the maximum fill capacity. In this case, trade size 41 (1 ½") is the appropriate choice, ensuring proper spacing and preventing overheating. Therefore, the correct answer is option c- trade size 41 (1 ½").
Full Question:
Determine the size of Liquid Tight Flexible Metal conduit required for three, No. 3, T90 NYLON and two No. 8 T90 NYLON conductors:
a- trade size 21 (¾")
b- trade size 35 (1 ¼")
c- trade size 41 (1 ½")
d- trade size 27 (1")