In last month's “Code Basics” article, starting on page 56 of the September issue, we spent most of our time discussing Class 1 circuits. Now, it's time to switch gears and focus on Class 2 and 3.

The wiring inside a dwelling that you cannot see may be an arc fault waiting to happen, due to improper installation; corrosion; damage caused by rodents, insects, or other pests; penetration by ...