Complete Distinction Of UL94 Flame Retardant Grades For Plastic Fasteners, Fire Selection Specification For PA66 / PC Cable Clips & Standoffs
Complete Distinction Of UL94 Flame Retardant Grades For plastic fasteners, Fire Selection Specification For PA66 / PC Cable Clips & Standoffs
plastic fasteners including nylon cable clips, insulating standoffs and cable clamps are widely adopted inside energy storage PACK, DC charging piles and industrial electrical cabinets. Short-circuit sparks may trigger continuous combustion of low-grade flame retardant plastics and generate ignitable molten droplets to spread fire. Many project audits require specified UL94 grades. Purchasers often confuse the application limits of V0/V1/V2/HB, leading to test failure and mass rework.
1. Core Index Comparison Table Of Four UL94 Flame Grades
| UL94 Grade | Single flame burning time | Total secondary combustion time | Molten drip characteristic | Typical raw material | Recommended application |
| V0 | ≤10s | ≤50s | No ignitable drips | Halogen-free flame retardant PA66, flame retardant PC | Sealed high-voltage energy storage cabin, charging pile high voltage module |
| V1 | ≤30s | ≤250s | Drips cannot ignite cotton | Modified flame retardant PA6 | Ventilated low voltage control cabinet, charging pile low voltage zone |
| V2 | ≤30s | ≤250s | Drips can ignite cotton | Conventional halogen-containing flame retardant nylon | Indoor ventilated low voltage non-core components only |
| HB (Horizontal Burn) | Slow continuous burning | No mandatory self-extinguish requirement | Continuous burning debris | Standard unmodified nylon, PP | Decorative outer parts without fire risk, forbidden inside high voltage cabins |
2. Mandatory Grade Selection Specification For New Energy plastic fasteners
1. Sealed high-voltage energy storage PACK cabin and charging pile high voltage accessories: UL94 V0 halogen-free plastic parts are mandatory; 2. Outdoor ventilated low voltage cabinets and charging pile low voltage cable clips: UL94 V1 plastic clips are acceptable; 3. Indoor ventilated weak current cabinets and non-safety circuit fittings: UL94 V2 can be adopted for cost control, forbidden in sealed high voltage environment; 4. HB plastic parts are limited to external decorative parts with zero fire spread risk, internal cabinet installation is prohibited.
3. Rectification Solutions For Common Flame Retardant Defects
1. Flame grade degradation after damp heat aging: Adopt hydrolysis-resistant modified flame retardant material; standard flame retardant nylon loses performance under long-term high temperature condensation; 2. Failed flame test: Confirm parts are produced with original modified flame retardant masterbatch; simple post-blending of ordinary nylon is not acceptable; 3. Wall thickness influence: Products thinner than 1.2mm easily fail flame test even with qualified raw material, reasonable thickness should be reserved during design; 4. Halogen-free requirement: European & American energy storage export projects require halogen-free material; halogen-containing V2 parts cannot satisfy IEC 61249 environmental standard.