cable tray arrangement

[Abdel Rahman Mohamed]

I want to ask about cables arrangement above cable tray with a separation distance (D) edge to edge, is the grounding conductor of the line conductor is included to calculate the separation distance D between the two current carrying conductor OR this separation distance should start after the diameter of grounding conductor.

in brief is the grounding conductor to be considered in the separation distance (D) or not.

Thanks in advance.

 

[Smart $]

IMO, yes. Spacing permits greater ampacity because of greater heat dissipation, and that stems in part from greater air flow around the [self-heating] conductors. Granted a grounding conductor is not a self-heating conductor. But to not provide the space between the ones that are self-heating would hinder the heat dissipation of the design.

 

[Sajid khan]

I didnot experience any case considering the ground conductor dia in calculation with line conductor dia to size the cable tray.

Sent from my GT-I9300I using Tapatalk

 

[Smart $]

I didnot experience any case considering the ground conductor dia in calculation with line conductor dia to size the cable tray.

392.22(A)(1)(a)...

(a) Where all of the cables are 4/0 AWG or larger, the​

sum of the diameters of all cables shall not exceed the cable​

tray width, and the cables shall be installed in a single​

layer. Where the cable ampacity is determined according to​

392.80(A)(1)(c), the cable tray width shall not be less than​

the sum of the diameters of the cables and the sum of the​

required spacing widths between the cables.​

Code doesn't specifically say you have to increase that width by another space and the diameter of the grounding conductor because you may be using steel tray which qualifies for and is used as the grounding conductor. If you must, elevate (assuming a horizontal run) and attach the grounding conductor to the side rail.

 

[Abdel Rahman Mohamed]

Thanks,

There is nothing in the code support this opinion.

 

[Abdel Rahman Mohamed]

Oh! OK sorry

 

[Smart $]

Thanks,

There is nothing in the code support this opinion.

Nothing specific. If getting inspected, ask inspector prior to installing (or ordering tray too narrow). If not getting inspected (or you are the inspector), use your best judgment.