Cable tray for power conductors

[charlie b]

I was just asked to comment on a contractor's request to use cable tray to distribute branch circuit wiring in an electrical room. There are a great number of branch circuits, and the contractor is concerned about being able to fit all the conduits within the space. I will look at the rules when I get to the office tomorrow morning. But can anyone offer any thoughts on the subject? Is this only allowed for wire type TC? If so, then there is an issue. This project is in Africa, and the conductors were made in Turkey, so they don't have the same conductor types as we do.

I have never used tray for power distribution, other than medium voltage runs through utility tunnels. What needs to be considered? Depth of fill? Insulation type and temperature ratings? Transition from conduit in corridor to tray in room to top of panelboards?

The contractor's sketch shows the tray running over the panels. I do not believe that would be a violation of the "dedicated space" rule, but I would want the tray to be well above the panels.

 

[augie47]

If he's under the NEC, single conductors runs must be 1/0 and larger and shall be marked "TC". In addition to 1/0 and larger single conductors there is a whole list of wiring methods the tray is allowed to support.

 

[ron]

If he uses cables, then you need to consider fill of the tray per Table 392.22(A) and the TC rating of the jacket.

I always hate it because it is too easy for someone to add cables later into the tray that we sized for other applications.