1. Material Codes (4 material standards)
| Material | Standard | Flame Retardancy | Application |
|---|---|---|---|
| ABS plastic | GB/T 12672 | V-2 | Indoor, dry |
| Flame-retardant PC | GB/T 14486 | V-0 | Indoor, damp |
| Painted steel | GB/T 7251.1 | Non-combustible | Indoor / Outdoor |
| Stainless steel | GB/T 4237 | Non-combustible | Outdoor / corrosive |
2. Ingress Protection Codes (GB/T 4208 IP code)
IP rating = IP + two digits, first digit for solids, second digit for liquids:
| IP | Solids | IP | Liquids |
|---|---|---|---|
| IP2X | ≥ 12mm solid objects | IPX4 | Splashing water |
| IP4X | ≥ 1mm solid objects | IPX5 | Water jets |
| IP5X | Dust protected | IPX6 | Powerful water jets |
| IP6X | Dust-tight | IPX8 | Continuous immersion |
3. Flame Retardancy Requirements (GB 8613)
GB 8613 Flame retardancy requirements for plastic junction boxes: ① Indoor use: rating ≥ V-2 (UL94); ② Recommended V-0 for public buildings / high-rises; ③ Glow-wire test: no ignition at 650°C. Steel / stainless steel junction boxes are inherently non-combustible and carry no flame retardancy requirement.
4. Environment Selection Comparison (5 environments)
| Environment | Material | IP rating | Flame retardant | Notes |
|---|---|---|---|---|
| Indoor, dry | ABS | IP20 | V-2 | Most economical |
| Indoor, damp | PC / steel | IP44 | V-0 | Gasket required |
| General outdoor | Painted steel | IP54 | Non-combustible | Rain hood |
| Outdoor rain exposure | Stainless steel 304 | IP65 | Non-combustible | Cable gland sealing |
| Coastal / chemical | Stainless steel 316 | IP66 | Non-combustible | 316 with molybdenum, corrosion resistant |
5. Junction Box Nameplate Requirements (8 mandatory items)
GB/T 7251.1 Junction box nameplates must show: ① Manufacturer name / trademark; ② Model; ③ Rated voltage; ④ Rated current; ⑤ Ingress protection (IP) rating; ⑥ Serial number; ⑦ Date of manufacture; ⑧ Applicable standard. Every junction box from Zhejiang Golden Unicorn ships with a complete nameplate.
FAQ FAQ
How do I read a junction box flame retardancy rating?
Check the UL94 standard: V-0 is the highest (self-extinguishing within 10s, no dripping), V-2 is next (self-extinguishing within 30s, dripping allowed but must not ignite cotton). V-2 is the minimum for indoor use; V-0 is recommended for public buildings.
What is the difference between IP65 and IP66?
IP65 protects against low-pressure water jets (6.3mm nozzle, 12.5L/min); IP66 protects against powerful water jets (12.5mm nozzle, 100L/min). Choose IP65 for general outdoor rain exposure; choose IP66 for heavy rain or coastal locations.
Can plastic junction boxes be used outdoors?
Yes, but choose flame-retardant PC material with a UV-stabilized formulation — standard ABS will age and become brittle outdoors. For outdoor use, steel or stainless steel is recommended.
Is a nameplate mandatory on a junction box?
Yes, it is requiredGB/T 7251.1 requires every junction box to ship with a nameplate showing 8 items including model / voltage / current / ingress protection (IP) rating.
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