Q: Am I required to use a grounding screw when working with metal electrical boxes? And what about grounding when using plastic boxes?

A: David Herres, a licensed electrician in Clarkesville, N.H., responds: Using a metal grounding screw is a convenient—and arguably the most reliable—method of grounding a metal wall box or light-fixture enclosure, but it isn’t the only method. Certain metal raceways, such as the familiar electrical metallic tubing (EMT) that fastens to...

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