Using 400.5(a)(2) allowable ampacity of flexible cables

[ghogg34]

I'm studying for an electrical exam and this question came up . Determine the ampacity of each THW conductor of an 8/3 awg multi conductor type w flexible cable used to supply fastened in place utilization equipment. Two of the conductors are current carrying conductors. I understand the general idea of the question my problem is how to decide which column to use 60c, 75c, 90c ? Any help would be appreciated!!

 

[Smart $]

Another misleading question. :weeping:

First off, Type W allowable ampacity is determined using Table 400.5...and the question does not provide the temperature rating of the cable.

Second, the question seems to steer you toward using perhaps Table 310.15(B)(16), and the column under THW (which is the 75°C column). Type W cable single conductors are usually listed as RHH/RHW-2, if they are listed at all as individual conductors. The individual conductor type only applies when the jacket is stripped off, and they are installed under a single conductor wiring method. No conditions of use are specified, so adjustment and correction is also unknown.

Inside the terminal enclosure, the only ampacity that applies is a coordination of the termination temperature limitation [110.14(C)), and without the terminal temperature rating specified, Code says we have to use the 60°C column of 310.15(B)(16). That said and given a size of 8/3 [copper], the circuit ampacity would be capped at 40A without any other information.