Canadian Electrical Code Ampacity Question

[Coco_HueHueHue]

Hello there!

Does anybody here knows the Canadian Electrical Code well?
Here is my problem.

I have a 1 X 3conductor 350 mcm 15kV TECK90 cable that runs buried on almost all of its run. Except at the end.
The last 15 feet will be outdoor in a ladder cable tray.

The ampacity tables given in the Canadian Electrical Code are more restrictive for outdoor cables in ladder cable trays than they are when cables are buried.

I am searching for an article inside of that code that would let me ignore the restrictive ampacity from the outdoor cable in ladder cable tray since it is only 15 feet long.
Does such an article exist? I have not found one so far.

Thanks!
Coco

 

[waross]

Think about it.
You don't reduce the ampacity of a feeder to a sub panel because the sub panel is "only 15 feet away".
But talk to the inspector. He will have the last say as to what is acceptable.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[wroggent]

I don't follow waross. Did you mean increase?

 

[Coco_HueHueHue]

Maybe i didn't express myself correctly.

In zone A, the ampacity of the cable is correctly sized. 98% of the run is in Zone A.
In zone B, the ampacity of the cable is a little bit too small because the code restricts the ampacity more in this environment, but it only consists of 15 feet of cable at the end of the run.

I was pretty optimistic that an article of the code could let me ignore that 15 feet undersized if it is not longer than a specific lenght.

 

[waross]

The 15 feet in air has a reduced ampacity compared to the buried portion.
Coco Eng Are you thinking about the rules concerning protection of cables?
See Rule 14-100 This rule lets you use short lengths of cable that are protected by greater than normal protective devices.
Each ungrounded conductor shall be protected by an overcurrent device at the point where it receives its supply
of current and at each point where the size of conductor is decreased, except that such protection shall be
permitted to be omitted in each of the following cases:
This rule applies to protection, not ampacity.
If the section of the cable with the reduced ampacity is adequate for the load at the reduced ampacity and the concern is that the protective devices may not properly protect the short section, you have a good case to present to the inspector.
If the reduced ampacity is less than the calculated load on the cable you may be out of luck.

Thinking outside the box:
Is it feasible to run the cable into a buried junction box and exit the box with three single conductors?
The cables could be routed to the tray through rigid PVC conduit (Sceptre^tm exiting throug an aluminum plate.
Don't splice, but break-out the three conductors and continue without splice.
Encapsulate or "pot" the junction box.
Installation will be challenging but do-able.
That may put the section of cables on the tray into Table #1, free air rating.


Bill
--------------------
"Why not the best?"
Jimmy Carter