Correction:
The answer to the second question in Code Quandaries on page 60 of the August 2004 issue incorrectly applied an ampacity taken from the 75°C column (65A) of Table 310.16 for the 6 AWG THHN conductor in question. It should have been taken from the 90°C column (75A), which would have changed the rating as follows:
(75A×0.80=60A)