NEC Table 610.14(A)

[Orndbri45]

Upgrading an existing crane in a plant I am working on.

As part of this design the existing feeder is 250 MCM triplex aluminum. This is from a Motor Control Center to the exposed contact conductors.

I thought that a new cable would be required based on the ampacities in 310. It was brought up that possibly using table 610.14 would be acceptable to use smaller cables. I still felt a new cable would be required since the table does not cover aluminum.

I however also dont know when this table is applicable. Is it any time you are routing cables associated with cranes, or is it past the contact conductors. Do you use NEC 310 or 610 for sizing the initial cable from the MCC to the disconnect and the disconnect to the contact conductors.

Appreciate the help and clarification on this.

 

[tortuga]

I still felt a new cable would be required since the table does not cover aluminum.

The note at the bottom of the table seems to support your position:

Note: Other insulations shown in Table 310.104(A) and approved for the temperature and location shall be permitted to be substituted for those shown in Table 610.14(A).

I however also dont know when this table is applicable. Is it any time you are routing cables associated with cranes, or is it past the contact conductors. Do you use NEC 310 or 610 for sizing the initial cable from the MCC to the disconnect and the disconnect to the contact conductors.

My understanding is the table is used for the conductors described in 610.41 and 610.42. There is a fine print note in the code that says

Informational Note: For the ampacities of conductors between
controllers and resistors, see 430.23.