Help with cable tray size

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kevinware

Senior Member
Location
Louisville, KY
I am installing wire basket cable tray under the floor in a data center and I plan to run "SOO" cord in that tray. I was reading through 392.9(E)(2) and it tells me to refer to table 392.9(E) column 2. At the present time I am using 4" tray so my allowable fill area is 2.5 square inches. The largest size "SOO" cable I would ever use would be 6/3. I am having trouble coming up with the proper area of my "SOO" cable. Looking at table 8 the area of #6 is .027 and looking at table 400.4 I don't get a "area" for the insulation thickness just a mils number of 45. Is the a formula I can use to help me size my cable tray for "SOO" cable sizes 12/2 through 6/3? Or can I do the math as follows: I will use #6/3 AWG as my example, from table 8.

#6 area = .027 x 3 = .081 square inches, divide this number into 2.5 square inches from table 392,9(E) which gives me a answer of 30 # 6/3 cables. Am I way off base?


Thanks for your help,

Kevin
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Re: Help with cable tray size

I?m making the assumption that the cables are being installed per Section 400.4(A)(9); otherwise, there is no provision in either Art 392 or 400 that recognizes installing SOO as permanent wiring in cable tray. See 392.3. 392.3(A) and Table 392.3(A).

If the assumption is correct, you will need to use the manufacture?s OD dimensions to calculate the fill. As an example only, I found one manufacture that makes SOO with an OD of .408?.

The cross sectional area = OD x π / 4

In this case .408x.408x 3.1416 / 4 ≈ .1307in
 

charlie tuna

Senior Member
Location
Florida
Re: Help with cable tray size

is there a space problem under the floor? the labor is basically the same --- go a little over sized and you'll make up the difference on the cable installation!!!
 
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