Cooper Bussmann CT02MAN manual Example NEC .9A2

Example - NEC® Section 392.9(A)(2)

Width selection for cable tray containing 600 volt multiconductor cables, sizes #3/0 AWG and smaller. Cable tray allowable fill areas are listed in Column 1 of Table 392.9.

30" Usable Cable Tray Width

Cross Section Of The Cables And The Cable Tray

Cable tray width is obtained as follows:

		(A)	(N)	Multiply (A) x (N)
Item	List	List Cable	List	Total of the
Number	Cable Sizes	Cross Sectional	Number	Cross Sectional
		Areas	of Cables	Area for Each Item
1.	3/C #12 AWG	0.17 sq. in.	20	3.40 sq. in.
2.	4/C #12 AWG	0.19 sq. in.	16	3.04 sq. in.
3.	3/C #6 AWG	0.43 sq. in.	14	6.02 sq. in.
4.	3/C #2 AWG	0.80 sq. in.	20	16.00 sq. in.

Method 1.

The sum of the total areas for items 1, 2, 3, & 4:

3.40 sq. in. + 3.04 sq. in. + 6.02 sq. in. + 16.00 sq. in. = 28.46 sq. inches

From Table 392.9 Column 1 a 30 inch wide tray with an allowable fill area of 35 sq. in. must be used. The 30 inch cable tray has the capacity for additional future cables (6.54 sq. in. additional allowable fill area can be used.)

Method 2.

The sum of the total areas for items 1, 2, 3, & 4 multiplied by

(	6 in.	) = cable tray width required
	7 sq. in.
3.40 sq. in. + 3.04 sq. in. + 6.02 sq. in. + 16.00 sq. in. = 28 46 sq. in.
(	28.46 sq. in. x 6 in.		) = 24.39 inch cable tray width required
	7 sq. in.

Use a 30 inch wide cable tray.

Notes:

1.The cable sizes used in this example are a random selection.

2.Cables - copper conductors with cross linked polyethylene insulation and a PVC jacket. (These cables could be ordered with or without an equipment grounding conductor.)

3.Total cable weight per foot for this installation.

31.9 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.

	Appendix Sheet 4
Cooper B-Line, Inc	Cable Tray Manual

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