Conductor sizing Table 310.16 in 2005 NEC

[Pacific]

I am preparing for C10 license exam and I am looking at Mike Holts Electrical NEC Exam Preparation book, 4th edition, in page 367.

There is an example to show what size of conductor to be selected for household oven.
Caculated Amp was 33Amp; then By Table 310.16, 8 AWG conductor was selected.
Isn't it supposed to be 10 AWG for upto 35 Amp accoding to Table 310.16?
It is confusing to pick which colum to use in Table 310.16 in general.
Should we use the first colum, upto 60C or the second, upto 75C in selecting a proper conductor size?
Thanks for your help.

 

[iwire]

I am preparing for C10 license exam and I am looking at Mike Holts Electrical NEC Exam Preparation book, 4th edition, in page 367.

There is an example to show what size of conductor to be selected for household oven.
Caculated Amp was 33Amp; then By Table 310.16, 8 AWG conductor was selected.
Isn't it supposed to be 10 AWG for upto 35 Amp accoding to Table 310.16?
It is confusing to pick which colum to use in Table 310.16 in general.
Should we use the first colum, upto 60C or the second, upto 75C in selecting a proper conductor size?
Thanks for your help.

In general for circuits under 100 amps or circuits wired with NM or SE you must use the 60 C column.

See 110.14 and 334.80

 

[LarryFine]

Lefty, welcome to the forum!

Isn't it supposed to be 10 AWG for upto 35 Amp accoding to Table 310.16?

It's never "supposed to be" the smallest conductor that's large enough, except where economy is concerned.

It's "permitted to be" as small as the applicable table column allows, at the smallest. It can always be bigger.

Check out 240.4(D), in addition to Bob's recommendations.