Editorial Correction
A reader recently wrote in with a question about the April 2008 issue “Code Quandaries” department, pointing out a possible error in the calculations for sizing the 90°C conductor ampacity. Per the author, there was an inadvertent error in the text. Right above “Step 4” on page 46, the number 420A in the calculation should have been 475A. This error did not affect the final answer.