Bhutan Lighting Distribution Box Standard Model

The standard lighting distribution box in Bhutan is typically a ZBW-type prefabricated substation, designed for 10/0.4kV networks with rated frequency 50Hz, offering integrated high-voltage and low-voltage switchgear, transformers, and protection devices.

Overview and Usage

The ZBW□ type prefabricated substation is a complete distribution unit that combines high-voltage switchgear, distribution transformers, low-voltage switchgear, energy metering devices, and power factor compensation devices in one or multiple enclosures according to wiring schemes. It is widely used for urban high-rise buildings, residential communities, industrial sites, street lighting, hotels, airports, docks, and shopping malls in Bhutan, providing a compact, safe, and reliable solution for electricity distribution .

Technical Specifications

• Transformer Rated Capacity: 50–1600 kVA, depending on load requirements .
• Rated Frequency: 50 Hz.
• Protection Level: IP23D, suitable for outdoor installation with moderate environmental exposure .
• Environmental Conditions:
  • Altitude ≤ 1000 m
  • Ambient temperature: -25°C to 40°C
  • Relative humidity ≤ 90% (monthly average at 25°C)
  • Wind speed ≤ 34 m/s
  • Ice thickness ≤ 20 mm
  • Pollution level II or III
  • Ground slope ≤ 5°
• Structural Features: Base frame welded from channel steel for high strength; enclosure made of composite materials with strong radiation resistance to reduce solar heat gain .

Standardization and Certification

The Bhutan Standards Bureau (BSB) develops and publishes national standards for electrical equipment, including distribution boxes. Standards ensure uniformity, safety, quality, and compatibility. Digital access to these standards is available through the eStandards platform, allowing users to purchase and download specifications for lighting distribution boxes and related electrical equipment .

Installation and Safety Considerations

• Must be installed in locations free from fire, explosion, severe pollution, chemical corrosion, or intense vibration .
• Designed to withstand 20 tons of ground pressure.
• Deep integration into the load center reduces floor space and investment while improving operational safety.
• Harmonious appearance and color are considered for urban and residential environments .

Summary

In Bhutan, the ZBW-type prefabricated substation serves as the standard model for lighting distribution boxes, combining multiple electrical functions in a single unit. It is engineered for reliability, safety, and environmental adaptability, with capacities ranging from 50 kVA to 1600 kVA, and conforms to national standards accessible via the Bhutan Standards Bureau. This model is suitable for a wide range of applications, including street lighting, residential, and industrial power distribution .