How well do you know the Code? Think you can spot violations the original installer either ignored or couldn't identify? Here's your chance to moonlight as an electrical inspector and second-guess someone else's work from the safety of your living room or office. It's your turn to identify the violation.
Hint: Near screw up (or down in this case)
Find the Answer
Whew! That was a close call for the conductors in this EMT. It was also a close call for the roofer sinking this screw into the metal decking! The workers who were making repairs to the roof almost sank a self-tapping sheet metal screw right through the pipe. This would have damaged the pipe and the wires inside the pipe, and could have even injured the roofer who was making the repairs.
This is exactly why Sec. 300.4(E) requires cables, raceways, and boxes to be installed so that there is a spacing of at least 1½ in. between the lowest portion of the metal-corrugated sheet roof decking material and the boxes, raceways, or cables. The Exception to 300.4(E) permits RMC and IMC to be installed without the 1½-inch spacing, since the wall thickness of these raceways is better able to protect the wiring inside them. Section 358.12(1) prohibits EMT from being used where it would be exposed to severe physical damage during or after installation. I would say that a self-tapping screw penetrating the EMT would constitute as severe physical damage.