BASIC CABLE SIZING FOR MOTORS

Table is for 480 V, 3 phase motors in magnetic conduit, 90 C cable, no direct sunlight, maximum 2% voltage drop running, maximum 10% voltage drop on starting.





HP



FLA


Cable Size


Cable O.D. (in)

NEC Conduit Size (in)

Max. Distance (ft)

Starter Size (Local)

Feeder Breaker (TM) Size for Local Starter
0.5 1.1 1/3/10 1 - .049 0.75 2491 1 or 00 15
0.75 1.6 1/3/10 1 - .049 0.75 1713 1 or 00 15
1 2.1 1/3/10 1 - .049 0.75 1305 1 or 00 15
1.5 3 1/3/10 1 - .049 0.75 989 1 or 00 15
2 3.4 1/3/10 1 - .049 0.75 1048 1 or 00 15
3 4.8 1/3/10 1 - .049 0.75 825 1 or 0 15
5 7.6 1/3/10 1 - .049 0.75 586 1 or 0 15
7.5 11 1/3/10 1 - .049 0.75 486 1 20
10 14 1/3/10 1 - .049 0.75 382 1 30
15 21 1/3/10 1 - .049 0.75 254 2 40
20 27 1/3/08 1 – 0.67 1 307 2 50
25 34 1/3/06 1 – 0.77 1 387 2 60
30 40 1/3/06 1 – 0.77 1 329 3 80
40 52 1/3/04 1 – 0.89 1.5 402 3 100
50 65 1/3/02 1 – 1.02 1.5 503 3 125
60 77 1-3-1/0 1 – 1.22 2 654 4 150
“ “ 3-1-1/0 3 – 0.629 2 “ “ “
75 96 1-3-1/0 1 – 1.22 2 525 4 175
“ “ 3-1-1/0 3 – 0.629 2 “ “ “
100 124 3-1-4/0 3 – 0.785 2.5 666 4 250
125 156 3-1-4/0 3 – 0.785 2.5 529 5 300
150 180 3-1-350 3 – 0.985 3 430 5 350
200 240 3-1-500 3 – 1.032 3.5 345 5 400
250 302 6-1-4/0 6 – 0.785 3 555 6 500
300 361 6-1-350 6 – 0.985 4 427 6 600
350 414 6-1-350 6 – 0.985 4 372 6 700
400 477 6-1-500 6 – 1.032 5 344 6 800
450 515 6-1-500 6 – 1.032 5 318 7 900
500 590 9-1-350 9 – 0.985 5 392 7 1000