Attic cable run near the gable
What's wrong here?
- Two cables are spliced in the open with no junction box
- NM cable may not be installed in an attic
- Wire connectors must never be wrapped with electrical tape
- Nothing. This installation is compliant
Show the answer and the code reference
The answer
The two NM cables are spliced together out in the attic with no junction box around the splice.
Correct choice: 1. Two cables are spliced in the open with no junction box
Where the wiring method is NM or any other cable, 300.15 requires a box or conduit body at every conductor splice point. A box contains heat and arcing if a connection loosens, protects the splice from being kicked or pulled apart, and keeps the cable sheaths clamped so the connectors are not carrying strain. A taped splice lying loose in blown-in insulation gets none of that, and nobody will ever find it when the circuit starts acting up.
How to fix it
Install a junction box secured to framing, bring both cables into it through listed clamps or connectors with the sheath extending into the box, remake the splice inside, and install a blank cover. The box has to stay accessible (314.29), so put it where it can be reached and found later, not out of reach under the insulation. If the cables are too short to reach a box, replace the cable run instead of hiding the splice.
Code references
NEC 2023 300.15 — Boxes, Conduit Bodies, or Fittings — Where Required
Where the wiring method is conduit, tubing, or a cable such as Type NM, a box or conduit body must be installed at each conductor splice point, outlet, switch, junction, termination, or pull point, unless one of the specific exceptions in 300.15(A) through (L) applies.
Drills citing 300.15NEC 2023 314.29 — Boxes, Conduit Bodies, and Handhole Enclosures to Be Accessible
In buildings and other structures, boxes and conduit bodies must be installed so the wiring in them can be made accessible without removing any part of the building or structure.
Drills citing 314.29
2026 NEC:same rule and number. The 2026 NEC keeps 300.15 and the requirement for a box or conduit body at each conductor splice point; the reported 2026 revision only clarifies that a box is not required at raceway terminations or transitions, which does not affect a loose NM splice in an attic. Confidence: medium
Minnesota
Minnesota adopted the 2023 NEC without amendment as the Minnesota Electrical Code (Minn. Rules 1315.0200; Minn. Stat. 326B.35), effective July 1, 2023, so 300.15 and 314.29 apply as published. That edition governs permits filed through Aug. 16, 2026; permits filed on or after Aug. 17, 2026 fall under the 2026 NEC; see the 2026 NEC note on this drill for how the cited section fares there.
How Minnesota adopts the NECWhy the other choices are wrong
- NM cable may not be installed in an attic. NM cable is a permitted wiring method in one- and two-family dwellings, attics included (334.10). In an accessible attic it needs guard strips where it runs across the tops of joists, or across rafters or studs within 7 ft of the floor or joists; with no permanent stairs or ladder, that protection is required only within 6 ft of the scuttle opening (334.23, 320.23(A)).
- Wire connectors must never be wrapped with electrical tape. Tape over a listed connector is not itself a violation; the problem here is where the splice is, not how it is wrapped.
- Nothing. This installation is compliant. Every splice in a cable wiring method has to be made in a box or conduit body (300.15). A taped splice lying loose in attic insulation is a classic attic fire start.