Gilles' Outlet

October 20, 2008

Repairing a dangerous electric junction box

Filed under: Electrical — Gilles @ 3:25 am

While removing a recessed medicine cabinet, a dangerous junction box is discovered. The dangerous box is removed, a new box is installed and re-wired.


Skill Level: 2~3 (Basic ~ Moderate)

Time Taken: About 1 hour

While remodeling houses, it is not uncommon to find work which was not properly done. Today’s article describes gross violations of the National Electric Code (NEC) resulting in a fire hazard. The junction box is replaced and re-wired to comply with appropriate building codes.

After pulling the medicine cabinet, I used my digital camera to take a picture of what was in the stud bay, just out of curiosity. Well, I was not disappointed. There was a metal junction box lurking in the wall. On this picture, you can see at least the following NEC violations:


  • 314.29 – Junction Boxes shall be accessible without damaging the building finish
    • –>This box is concealed behind drywall.
  • 312.5 – Use of proper fittings to ensure wires are secured properly
    • –> No clamps are used to secure wires.
  • 314.16 – Volume of junction boxes
    • –> This box is way to small for 8 14/2 wires. This is a fire hazard.


Left: I turned the power off at the main panel and verified that all wires were no longer energized. Remember that you sometimes must trip more than one breaker (up to six in fact) to completely de-energize the whole house. Always double check that the wires you intend to work on are no longer energized.


Right: I used a pry bar to loosen the top nail of the box. It was much more difficult that it looks like. I had to be gentle enough not to damage wires, yet apply enough force to remove the nail.

Eventually, the top nail gave way and I was able to pry the bottom nail. The box was freed from the framing.

Left: This is a 34 cu (cubic inches) remodel junction box. It can contain up to 17 conductor equivalent 14 gauge wires. NEC article 314.16 describe how to calculate minimal volume of a box.

In this situation, there are 8 14/2 wires in the box, no device and no internal clamp. So we have 2 (hot + neutral) * 8 (there are 8 NM wires in the box) + 1 (all ground wires in a box count for one conductor equivalent). The box needs to accommodate 17 conductor equivalent. For 14 gauge wires, a conductor equivalent requires 2 cubic inches. The box must be at least 2 * 17 = 34 cubic inches.

Right: I decided the location of the new box and marked the opening with a pencil.

Left: I progressively cut the drywall for the new box. This revealed more of the dangerous J-Box. It is obviously very crowded.

Right: Another detail of the J-Box. It is difficult to see on the picture, but there is another NEC violation:


  • 314.4 – All metal boxes shall be grounded
    • –> The box itself was not grounded.

Left: I finished cutting the hole with a drywall saw.


Right: Detail of wires entering the box. They are not clamped as required by code but the jacket of the top NM wire has been slightly damaged by the sharp edge of the box. This is a fire hazard. If the metal box cuts the insulation and reaches a wire, this can cause a spark and start a fire.

At this point, I marked all wires and made sure I recorded all connections on a piece of paper. I unwired all connections. Wires were not even twisted properly. This was another fire hazard.

I pulled wires in the new box and secured the remodel box to the wall. Plastic boxes like these have built-in clamps which secure wires at the box.

Damaged wires were replaced. It was now a matter of making the connections according to the notes I wrote in the previous step.

Making a connection is easy: twist wires with a Lineman’s pliers so both wires are twisted tight against each other and cap the twist with an appropriately sized nut (I used yellow nuts which handles two 14 gauge wires according to the manufacturer).

After finishing the wiring, I carefully pushed all wires in the box. I tired to arrange the as neatly as I could to facilitate identification of circuits. Later on, the box will be capped with a 2-gang blank wall plate to conceal wires yet allow for easy access if needed.


This work was clearly not performed by a licensed electrician, not permitted and not inspected. This "do it yourself specials" exposed occupants of this house to fire hazards. When doing any kind of work on any building, always consult your local building department, professional(s) and respect all local and national building codes.

DISCLAIMER: Procedures demonstrated in this article may or may not meet code in your area. Consider this article for entertainment purposes only. I cannot be held responsible for anything that may happen when trying to duplicate anything shown here. Before attempting to perform any work on any building, always consult a licensed professional.

Tools Used:

  • Hammer
  • Drywall Saw
  • Flat Screwdriver
  • Pry bar
  • Lineman’s pliers
  • Impact Driver

Materials Used:

  • 14/2 wire (to replace damaged wires) 
  • Yellow Wire Nut (accommodates two 14 gauge wires) 
  • 34 cubic inches remodel plastic junction box
  • Two-Gang blank wall plate (not show in article)


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