how many circles can be contained within a rectangle 5

[searcher123]

Hi All

I am trying to determine how many round cables can be contained within a rectangular duct. I have found a formula for circles contained within another circle but would like to know circles within a rectangle. Can anyone help me with this

 

[civilperson]

All cables do not have the same diameter. Cable trays have rated maximum loads in pounds per foot and in number/size of conductors. Access for replacement and labeling is standard practice and requires some available excess volume for pulling cords and connection sheaths. Filling a cable tray to full is not a good idea.

 

[jpankask]

The Electrical Code is very specific on how many of each size cable may be in a cable tray, conduit, etc. All cables need to be taken into account, whether energized at the time or not. Even if it isn't energized now, at some point in the future some engineer may decide to use it. Depending on the type of conduit and the specific cables, the cable fill may be as little as 40% of the available area so it might not be enough to use a CAD program to find out the maximum and then take 50%. You REALLY need to refer to the Code that is applicable for your answer.

 

[waross]

In Canada, I understand that there is a derating factor applied to the ampacity of the conductors but no limit to the number of cables in a tray if they are properly derated. I'm out of town so I can't check for sure right now.
In some industrial plants the cables are heaped in the middle of the tray like a load of gravel. But, due to inevitable crosses and tangles, the cables take more space than your calculation will indicate. Oh, and corners often take more again.

Bill
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"Why not the best?"
Jimmy Carter