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. Joe, who has a knack for finding shoddy electrical work, did the dirty work and found this mess. Now it's your turn to identify the violation.
For starters, the cable clamps in this junction box are designed for metallic cable assemblies, not NM type cables. This is a misuse of the listing of this product. In addition, take a look at bare grounding conductors. Notice anything wrong? You should have said the grounding conductors from each cable are not properly secured, and violate the requirements of 250.148, Continuity and Attachment of Equipment Grounding Conductors to Boxes.
The rule states, "Where circuit conductors are spliced within a box, or terminated on equipment within or supported by a box, any equipment grounding conductor(s) associated with those circuit conductors shall be connected within the box or to the box with devices suitable for the use in accordance with 250.148(A) through (E)."
As per 250.148(A), "Connections and splices shall be made in accordance with 110.14(B) except that insulation shall not be required."
As per 250.148(B), "The arrangement of grounding connections shall be such that the disconnection or the removal of a receptacle, luminaire, or other device fed from the box does not interfere with or interrupt the grounding continuity."
As per 250.148(C), "A connection shall be made between the one or more equipment grounding conductors and a metal box by means of a grounding screw that shall be used for no other purpose, equipment listed for grounding, or a listed grounding device."
On a final note, we can see the installer had trouble with the twist-on wire connectors. It appears they either didn't screw the connectors on tight enough or stripped off too much wire insulation, which they then decided to "fix" by wrapping two of the connections in electrical tape.