10 Most Common Electrical Mistakes DIYers Make

Overfilling Electrical Boxes

Mistake: Box too small

This mistake refers to the use of an inadequate box size when accommodating multiple wires and devices. When there are too many wires stuffed into a small box, it can result in overheating, short-circuiting, and potential fire hazards. The National Electrical Code specifies minimum box sizes to minimize these risks.

Solution: Install a larger box

The suggested solution involves calculating the minimum box size required based on the number of wires and components present. To determine the minimum box size, the following items should be considered:

Each hot wire and a neutral wire entering the box count as 1.

All ground wires combined count as 1.

All cable clamps combined count as 1.

Each device (switch or outlet, excluding light fixtures) counts as 2.

The total is then multiplied by 2.00 for 14-gauge wire or by 2.25 for 12-gauge wire to determine the minimum box size required in cubic inches. It is essential to select a box with at least this much volume to accommodate the wiring safely.

Plastic boxes typically have the volume stamped inside, often located on the back. Steel box capacities are listed in the electrical code and may require measuring the height, width, and depth of the interior to calculate the volume accurately.