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Views： 8 Author： Mark Zhang Publish Time： 2026-07-17 Origin： 本站
This article compares UL/ETL listed junction boxes in plastic and iron options from SINGI. It covers safety certifications, material properties, and choice criteria for industrial and commercial applications.
Note: All SINGI junction boxes carry valid UL and ETL markings. Always verify with local codes before installation.
Junction boxes house and protect electrical connections from environmental factors and physical damage. A UL/ETL listed junction box has been tested by Underwriters Laboratories (UL) or Intertek (ETL) to meet required safety standards for fire, shock, and mechanical robustness. In the US and Canada, these listings are widely accepted by authorities having jurisdiction (AHJ).
SINGI offers both plastic (polycarbonate, ABS) and iron (cast iron, sheet steel) junction boxes in sizes from 4"x4" to 12"x12" and larger. Each model undergoes rigorous testing per UL 50 (Enclosures for Electrical Equipment) and CSA C22.2 standards.
Uncertified junction boxes pose risks of arc faults, corrosion, and insufficient sealing. Using a UL/ETL listed junction box ensures:
For industries like solar, oil & gas, or manufacturing, insurance and liability mandate listed boxes.
Choose between plastic and iron based on these factors:
| Parameter | Plastic (Polycarbonate) | Iron (Cast/Sheet) |
|---|---|---|
| Corrosion resistance | Excellent | Moderate (coated) |
| Impact strength | Good | Excellent |
| EMI shielding | None | Good |
| Weight | Light | Heavy |
| Temperature range | -40°C to 120°C | -50°C to 150°C |
| Typical applications | Outdoor, wet, chemical | Indoor, high temp, EMI |
For outdoor solar farms, plastic boxes resist UV and salt spray. For industrial motor controls, iron boxes dissipate heat and block interference.
SINGI provides both plastic (SJB-P series) and iron (SJB-I series) junction boxes with UL/ETL listing. The plastic models are available in NEMA 4X and 6P ratings; iron models in NEMA 1, 3R, 4, and 12. Accessories include mounting brackets, cable glands, and pre-punched knockouts.
For volume procurement, contact SINGI at https://www.singi.com/Plastic-Iron-junction-box.html to request datasheets and project quotes.
Both indicate compliance with the same standards. ETL is accepted as equivalent to UL by most AHJs.
Only if rated for the specific class and division. SINGI’s plastic boxes are suitable for non-hazardous environments. For hazardous areas, use iron boxes with explosion-proof ratings.
Yes. Iron boxes must be bonded to the equipment grounding conductor per NEC Article 250.
For a complete UL/ETL listed junction box solution, explore SINGI’s range at https://www.singi.com/Plastic-Iron-junction-box.html. Request a sample or bulk pricing today.
References:
[1] IEC 60947-1. Low-volt-level switchgear and controlgear - Part 1: General rules [S]. 2020.
[2] IEC 61439-1. Low-volt-level switchgear and controlgear assemblies - Part 1: General rules [S]. 2020.
[3] GB/T 14048.1-2019. Low-volt-level switchgear and controlgear - Part 1: General rules [S]. 2019.
