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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
2222
111
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