Cable Ampacity in a cable Tray

[bobby mercier]

In a cable tray, if i have more cable than table 392.22(A) allow, can i use table 310.15(B)(3)(a) to oversized my cable?

Per Canadian Electrical Code, the answer is Yes
Per NEC i can't find a relation between 392.8 Ampacitiy of Conductors in Cable Trays and the table 310.15(B)(3)(a).

 

[rbalex]

Except for multiconductor cables with more than 3 current carrying conductors, there is no direct relationship between cable tray conductor ampacities and 310.15 (B)(3)(a) in the NEC. All ampacities are computed in Section 392.80.

One of the subtile differences between the NEC and the CEC is cable trays are NOT raceways in the NEC; they are in the CEC.

BTW if you have more fill than Section 392.22(A) allows, you are in violation of the NEC.

 

[Canton]

Except for multiconductor cables with more than 3 current carrying conductors, there is no direct relationship between cable tray conductor ampacities and 310.15 (B)(3)(a) in the NEC. All ampacities are computed in Section 392.80.

One of the subtile differences between the NEC and the CEC is cable trays are NOT raceways in the NEC; they are in the CEC.

BTW if you have more fill than Section 392.22(A) allows, you are in violation of the NEC.

Find the minimum ampacity that you need for your cables, make sure that they will be installed per 392.22 and use table 310.15(B)(16) for multiconductor or single conductor use 310.15x(x) and so on....392.80 (2011) spells out ampacity for you. There are many variables and tables to use depending on how and what size of cable you are installing.

The Tables have already been adjusted for a higher ampacity, but will be derated to a certain percentage depending on how you do your installation.

Read carefully....cable tray calculation can have a lot of variables.

 

[bobby mercier]

Except for multiconductor cables with more than 3 current carrying conductors, there is no direct relationship between cable tray conductor ampacities and 310.15 (B)(3)(a) in the NEC. All ampacities are computed in Section 392.80.

One of the subtile differences between the NEC and the CEC is cable trays are NOT raceways in the NEC; they are in the CEC.

BTW if you have more fill than Section 392.22(A) allows, you are in violation of the NEC.

Per The Canadian Electrical Code, i can install as many 3 conductors cables as the load capacitiy of the cable tray allow me as long as i oversized my cable acording CEC table 5C (NEC table 310.15 (B)(3))
Per the NEC, it seem ther is no ''OVERSIZE factor'' for 3 conductors power cables in a cable tray. I have to not exceed max fill area of table 392.22 (A)

Am i Right ?

Sorry for my bad English writing........

 

[rbalex]

The ampacities in Section 392.80 are based on the fills permitted by 392.22 and are the only fills and ampacities permitted per the NEC. Basically, you aren't permitted to "overfill" a cable tray in the NEC. As I mentioned earlier, the CEC treats cable tray as a raceway and permits alternate means of adjustment.

Canton's post was also on point - choose the required ampacity first and work backwards.

Your English is fine.