Electrical Box Size Calculator

Formula

To calculate the Electrical Box Size (BS):

\[ BS = (N \times D) + A \]

Where:

\(BS\) is the Electrical Box Size in cubic inches
\(N\) is the Total Number of Conductors
\(D\) is the Volume Allowance per Conductor in cubic inches
\(A\) is the Volume Allowance for Devices or Fittings in cubic inches

What is Electrical Box Size?

Electrical Box Size refers to the physical dimensions of the box that houses electrical connections, such as switches, outlets, and light fixtures. The size of the box is determined by the number and size of the wires, devices, and fittings that will be contained within it. It is crucial to choose the correct size to ensure safety and adherence to electrical codes. The box size is typically measured in cubic inches and can vary depending on the specific electrical application.

Example Calculation 1

Let's assume the following values:

Total Number of Conductors (\(N\)) = 10
Volume Allowance per Conductor (\(D\)) = 2.25 cubic inches
Volume Allowance for Devices or Fittings (\(A\)) = 5.0 cubic inches

Using the formula:

\[ BS = (10 \times 2.25) + 5.0 = 27.5 \text{ cubic inches} \]

The Electrical Box Size is 27.5 cubic inches.

Example Calculation 2

Let's assume the following values:

Total Number of Conductors (\(N\)) = 8
Volume Allowance per Conductor (\(D\)) = 2.5 cubic inches
Volume Allowance for Devices or Fittings (\(A\)) = 4.0 cubic inches

Using the formula:

\[ BS = (8 \times 2.5) + 4.0 = 24.0 \text{ cubic inches} \]

The Electrical Box Size is 24.0 cubic inches.