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: Someone's got a few screws loose
An electrician discovered this pipe during a troubleshooting call. The overcurrent device protecting the circuit wires in this EMT never opened during a ground fault event. Luckily, someone noticed the pipe arcing/sparking and decided to call an electrician to check it out.
Section 250.118(4) permits EMT as an equipment grounding conductor, and 250.120(A) requires all connections, joints, and fittings be made tight using suitable tools. It appears the screws on this coupling were never tightened.
Section 250.4(A)(3) requires normally non-current-carrying conductive materials enclosing electrical conductors be connected together as well as to the electrical supply source in a manner to establish an effective ground-fault current path, which is defined in 250.2 as "an intentionally constructed, low-impedance electrically conductive path designed and intended to carry ground-fault current from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device." The loose screws on the EMT coupling created a high-impedance path for fault current, which resulted in severe arcing at the coupling.
Imagine if this pipe was located in an area that was not visible. If left unchecked, the heat generated by the arcing could have easily started a fire.