Conduits conductor capacity:
Conduit Size   No. of conductors allowed  Raceway Fill
  CONDUCTOR SIZE
  #12 #10 #8 #6 #4 #3 #2 #1 1/0 2/0 3/0 4/0 250 300 400 500
1/2" 6 6 3 1 1 1 1 1 - - - - - - - -
3/4" 11 11 5 4 2 1 1 1 1 1 1 1 - - - -
1" 18 18 9 6 4 3 3 1 1 1 1 1 1 1 - -
1 1/4" 32 32 16 11 7 6 5 3 3 2 1 1 1 1 1 1
1 1/2" 44 44 22 15 9 8 7 5 4 3 3 2 1 1 1 1
2" 73 73 36 26 16 13 11 8 7 6 5 4 3 3 1 1
2 1/2" 104 104 51 37 22 19 16 12 10 8 7 6 4 4 3 2
3" 160 160 79 57 35 29 25 18 15 13 11 9 7 6 5 4
4" 276 276 136 98 60 51 43 32 27 22 18 15 12 11 8 7

Notes:
1. THWN, Tw or THHN wiring.
2. Refer to NEC, Chapter 9.
3. Number of conductors in conduit is determined from allowable fill- NEC,
Tables, Chapter 9. For 3 conductors or more in a conduit, 40% fill applies.
4. When conductors are not of the same size, number cannot exceed allowable
 fill limits of Tables in Chapter 9, NEC.