Is there a max ampacity derating factor

[JEFF MILLAR]

36 - 3 / C. xhhw. 460 V. Motor Feeders installed as follows.

1 - Concrete floor trench, in. substation , no cable supports provided. ( code violation , yes ) Cast iron cover in removable sections.
2 - Exit the concrete 10 inch wall through concrete sleeves into. underground trench. Cables installed touching ( 36 - 3 / C )
3 - Vertical rise out of the trench ( no conduit elbows ) up into ladder type cable trays, cables installed touching,
more than one layer. ( 50 Deg. C. ambient design temperature. )
4 - Exit the cable trays and run in individual conduit to the motor. load.

There must be more than one code violation here with this design.
I would like to know if there is one MAXIMUM AMPACITY DERATING FACTOR that would be applicable for this type of
industrial. installation.
If you would be kind and share your experience , would be appreciated

 

[Julius Right]

In my opinion it is about 36 three core cables of 10 awg XLPE [90oC] insulated.

The maximum ampacity according to Table 310.15(B)(16) for one cable is 40 A.

For concrete floor trench will be 40% derating as per Table 310.15(B)(3)(a)

For ladder of 6" width but 50oC ambient according toTable 310.15(B)(2)(a) 40%

For underground trench [filled] 40%

For 10 inches wall through = negligible.

For individual conduit [40oC ambient air] negligible

 

[JEFF MILLAR]

Great response, thank you