Size and Specifications of Level 3 Distribution Box

A Level 3 distribution box is typically fabricated from 2 mm GI sheet steel, with IP55 protection, slanted roof, and provisions for MCCBs, bus bars, and cable glands.

Construction and Material

• Body Material: 2 mm galvanized iron (GI) sheet steel with reinforced channels for structural integrity .
• Roof: Slightly slanting on both sides with a 50 mm overhang at front and back to prevent water ingress .
• Doors and Locking: Godrej Type 3-position locking system with concealed hinges; manual locking provision galvanized to prevent rust .
• Earthing: Two solid earthing points on either side .
• Protection Rating: IP55 for outdoor boxes, ensuring dust and water resistance .

Dimensions

• Illustrative Dimensions: Tolerances of ±10% are allowed; manufacturers may specify their own dimensions .
• Internal Layout: Provision for one bus bar arrangement with 4-pole MCCB and one outgoing feeder with 2 sets of 3-pole MCCBs for 100 kVA LT distribution .
• Bus Bars: Copper flat bars, typically 25x4 mm, with heat-shrinkable insulation tubing in red, yellow, blue, and black .

Electrical Components

• MCCBs: Conforming to IS:13947 with magnetic trip release and manual reset; neutral unbalance protection included .
• Cable Entry: Heavy-duty, double compression brass cable glands for incoming and outgoing cables; detachable plates for fixing .
• Bus Bar Clearance: Adequate spacing between phases and metallic/heat-resistant insulating barriers to prevent heat transfer during faults .

Additional Features

• Internal Lighting: Provision for lighting inside the cabinet .
• Identification: Purchaser's name, serial number, and non-detachable nameplate on sidewalls .
• Standards Compliance: IEC 60439-3 for low-voltage switchgear assemblies; type-tested at CPRI or government-approved labs .

Optional Specifications

• Outdoor vs Indoor: Outdoor boxes require IP55, while indoor boxes may have IP30 protection .
• Bus Bar Sizes for Higher Ratings: For 63/100 kVA, aluminium busbars 72x50x8 mm; for 160/315 kVA, 120x50x15 mm .
• Feeders and Droppers: Incoming and outgoing droppers sized according to KVA rating, with PVC insulating sleeves for phase identification . This configuration ensures mechanical durability, electrical safety, and compliance with relevant standards, making Level 3 distribution boxes suitable for residential, commercial, and industrial low-voltage applications.