Cable Bending Radius in Cable Tray

[timm333]

Just thought to ask. In the attached sketch, the width of the cable tray is 12". The cable is pulled at the center of this cable tray. How do we calculate the value of radius (R) of the circle in this attached sketch?

Basically I am trying to prove that this cable can be pulled in this cable tray without the need of a 90 Deg elbow. The bending radius of the cable is 12.2". So if radius (R) is equal to or greater than 12.2” then this cable can be puled without the need of a 90-Deg elbow. Thanks

 

[HarrySlother]

You can get different radius bends for tray. Here's a snip of some aluminum, horizontal bend options from Eaton's B-line catalog. I think 24" is typically the minimum, so your 12.2" bending radius would be ok.

 

[don_resqcapt19]

Just thought to ask. In the attached sketch, the width of the cable tray is 12". The cable is pulled at the center of this cable tray. How do we calculate the value of radius (R) of the circle in this attached sketch?

Basically I am trying to prove that this cable can be pulled in this cable tray without the need of a 90 Deg elbow. The bending radius of the cable is 12.2". So if radius (R) is equal to or greater than 12.2” then this cable can be puled without the need of a 90-Deg elbow. Thanks

Why would you not use the 90° fitting made for that purpose? If you do it like shown, you really limit the capacity of the tray because of the cable bending radius.

The cutting and field fabrication of what you show would probable cost more than using the correct fitting.

 

[timm333]

It is not the issue of cost. It is just that it is hard to get approval for additional material like 90° fitting.

Here we only have two cables each of bending radius 12.2”. The original design was to put these two cables in 4” wide tray. But 4” wide tray is not available so we are using 12” wide tray. As there will only be two cables in this 12” wide tray, so I thought we can do it without 90° fitting. But I am not able to figure out how to calculate the radius R as shown on the attached sketch.

 

[don_resqcapt19]

Assume a 90°, 45°, 45° triangle with the hypotenuse running out from the inside of the corner of the tray. If you run the inside of the first cable about 8.6" from the tray, you can get a 12.2" radius. The second cable would be to the outside of that and have a larger radius.