Distribution boxes vary in size depending on type, series, and number of circuits, with typical dimensions ranging from 100–415 mm in length, 105–323 mm in width, and 75–140 mm in height.

Standard Dimensions by Series

• MB-ABC Series: Length 200–328 mm, Width 172–174 mm, Height 95 mm, suitable for modular AC circuits 220V/380V in residential and commercial buildings .
• HA, HK, LGD Series: Length 100–415 mm, Width 105–323 mm, Height 75–140 mm, made of flame-resistant ABS plastic .
• TOP Series (TOP-TS, TOP-TF, TOP-LS, TOP-PS, TOP-PF, TOP-S): Dimensions vary according to the number of ways (1–36 ways), with length, width, and height specified per model .
• Single-phase and multi-element boxes: Outer frame sizes range from 610×550×170 mm to 860×840×170 mm, with embedded wall sizes slightly smaller to accommodate installation .

Material and Construction

Most distribution boxes are made from ABS or polycarbonate, providing flame resistance, impact resistance, and insulation properties. Wall-mounted or embedded designs are common, with thicknesses typically between 4–6 mm .

Determining the Size

The size of a distribution box depends on:

1. Number of switches or circuit breakers: Each switch typically requires 18 mm of width; additional space is added for wiring and safety clearances .
2. Incoming line size: Larger cables require more depth to accommodate bending radius and terminal connections .
3. Installation type: Embedded boxes require slightly smaller dimensions than surface-mounted boxes to fit within walls .

Measurement Guidelines

• Length (L): Longest side of the box base.
• Width (W): Shorter side of the box base, perpendicular to length.
• Height (H): Vertical distance from the base to the top of the box .
• Proper sizing ensures safe installation, prevents overcrowding, and allows for future expansion. By considering the series, number of circuits, and installation requirements, you can select a distribution box with appropriate length, width, and height for your electrical setup.