Approximate # of Wires in Conduit

Chart for Thhn wire Check Code Book for actual types and charts;
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|   1/2   |   3/4   |   1   |  1-1/4  |  1-1/2  |   2   |   2-1/2  |   3   |
|---------|---------|-------|---------|---------|-------|----------|-------|
|AWG #wire|AWG #wire|AWG#wir|AWG#wires|AWG#wires|AWG#wir|AWG#wires |AWG#WRs|
| 14 (13)  | 14 (24) |14 (39)| 14 (69) | 14 (94) | 14(154)| 14     |       |
| 12 (10)  | 12 (18) |12 (29)| 12 (51) | 12 (70) | 12(114)| 12(164)|12(   )| 
| 10 (6)  | 10 ( 11) |10 (18)| 10 (32) | 10 (44) | 10(73)| 10 (104)|10(160)|
|  8 (3)  |  8 ( 5) | 8 ( 9)|  8 (16) |  8 (22) |  8(36)|  8 ( 51) | 8( 79)|
|  6 (1)  |  6 ( 2) | 6 ( 6)|  6 (11) |  6 (15) |  6(26)|  6 ( 37) | 6( 57)| 
|  4 (1)  |  4 ( 1) | 4 ( 4)|  4 ( 7) |  4 ( 9) |  4(16)|  4 ( 22) | 4( 35)|
|  3 (1)  |  3 ( 1) | 3 ( 3)|  3 ( 6) |  3 ( 8) |  3(13)|  3 ( 19) | 3( 29)|
|  2 (1)  |  2 ( 1) | 2 ( 3)|  2 ( 5) |  2 ( 7) |  2(11)|  2 ( 16) | 2( 25)|
|  1      |  1      | 1 ( 1)|  1 ( 3) |  1 ( 5) |  1( 8)|  1 ( 12) | 1( 18)|
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The number of conductors shall not exceed the percentage fill
specified in table 1, chapter 9.
(fpn) for conductor cross sectional area see tables:
5,5a,6,7,8 and the applicable notes to tables at the
beginning of chapter 9.

The maximum percentage of conduit fill for more than three
conductors in a conduit or raceway is 40 percent. (all 
conductors except lead covered)

Units of area:

	The circular mil is the unit of cross section used in the
American wire gauge (AWG). The term Mil means one thousandth of an
inch (0.001 inch). A circular mil is the area of a circular wire
with a diameter of one mil, 0.001".

	The circular mil area of any solid cylindrical wire is equal
to its diameter (expressed in mils) squared. For example, the area in
circular mils of a wire having a diameter of 3/8 of an inch (0.375)
equals 375 x 375 = 140,625 CM. The diameter in mils of a solid circular
wire is equal to the square root of its circular mil area. Assuming that
a conductor has an area of 500,000 CM, its diameter in mils is the 
square root of 500,000, which is equal to 707 mils, or 0.707 inch
(approximately). The area in square inches of a wire whose diameter
is one mil is Pi D squared /4 = 0.7854 x 0.001 squared = 0.0000007854 sq.in.

	The square mil is the area of a square whose sides are each
one mil (0.001 inch). Hence, the area of a square mil is 0.001 squared,
or 0.000001 square inch. With reference to the previous definitions of
the circulare mil and the  square mil, it is obvious that in order to
convert a unit of circular area into its equivalent area in square mils
the circular mil must be multiplied by Pi/4, or 0.7854, which is the 
same as multiplying by 1.273.

	These relations may be written as:
	
	Area = diameter squared = circular mils (CM)

	Square Mils = circular mils times 0.7854 = circular mils divided
	by 1.273.

	Circular mils = square mils divided by 0.7854 = square mils
	times 1.273.

	By this method any circular conductor may be converted into a
rectangular conductor (a bus bar) containing an equivalent area or 
current carrying capacity.

	Table 5 of the NEC gives the approximate area in circular mils
and square mils of different sizes of wire.
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