Cooper Bussmann CT02MAN User Manual
Page 51
49
Cable Tray Manual
Cooper B-Line, Inc
Example - NEC
®
Section 392.9(A)(3)
Width selection for cable tray containing 600 volt multiconductor cables, sizes #4/0 AWG and larger
(single layer required) and #3/0 AWG and smaller. These two groups of cables must have dedicated
areas in the cable tray.
Cable tray width is obtained as follows:
A - Width required for #4/0 AWG and larger multiconductor cables -
(D)
(N)
Multiply (D) x (N)
Item
List
List Cable
List Number
Subtotal of the
Number
Cable Sizes
Outside
of Cables
Sum of the Cables
Diameter
Diameters (Sd)
1.
3/C - #500 kcmil
2.26 inches
3
6.78 inches
2.
3/C - #4/0 AWG
1.55 inches
4
6.20 inches
Total cable tray width required for items 1 & 2 = 6.78 inches + 6.20 inches = 12.98 inches
B - Width required for #3/0 AWG and smaller multiconductor cables -
(A)
(N)
Multiply (A) x (N)
Item
List
List Cable
List Number
Total of the
Number
Cable Sizes
Cross Sectional
of Cables
Cross Sectional Area
Area
For Each Item
3.
3/C #12 AWG
0.17 sq. in.
20
3.40 sq. in.
4.
3/C #10 AWG
0.20 sq. in.
20
4.00 sq. in.
5.
3/C #2 AWG
0.80 sq. in.
4
3.20 sq. in.
Total cable tray width required for items 3, 4, & 5
Actual cable tray width is A - Width (12.98 in.) + B - Width (9.09 in.) = 22.07 inches
A 24 inch wide cable tray is required. The 24 inch cable tray has the capacity for additional
future cables (1.93 inches or 2.25 sq. inches allowable fill can be used).
Notes:
1. This ratio is the inside width of the cable tray in inches divided by its maximum fill area in
sq. inches from Column 1 Table 392.9.
2. The cable sizes used in this example are a random selection.
3. Cables - copper conductors with cross linked polyethylene insulation and a PVC jacket.
4. Total cable weight per foot for this installation.
40.2 lbs./ft. (Cables in this example do not contain equipment grounding conductors.)
This load can be supported by a load symbol "A" cable tray - 50 lbs./ft.
24" Usable Cable Tray Width
9.09"
1.93"
12.98"
Cross Section Of The Cables And The Cable Tray
2
2
2
2
1
1
1
Appendix Sheet 5
(3.40 sq. in. + 4.00 sq. in. + 3.20 sq. in.)
= (10.6 sq. in.)
= 9.09 inches
(
)
6 in.
7 sq. in.
(
)
6 in.
7 sq. in.
1
1