UL 3135 — Silicone Wire Without the Covering Requirement
UL 3135 occupies a specific niche in the silicone wire family: same 200°C / 600V performance as UL 3071 and UL 3172, same 30 mils silicone wall thickness, but no covering specification required by the UL listing. For German engineers searching UL 3135 600V silicone enclosed wire Germany, this Style is the cost-effective choice when the application is totally enclosed and the equipment chassis itself provides the mechanical protection that would otherwise come from an SF-2 covering or glass braid.
UL 3135 vs Other 600V Silicone Styles
| UL Style | AWG Range | Covering | Best for Application |
|---|---|---|---|
| UL 3135 | 26-12 AWG | None specified | Totally enclosed appliances |
| UL 3071 | 18-13 AWG | SF-2 covering (UL 66) | Mechanical assembly access |
| UL 3172 | 26-18 AWG | Glass/aramid braid | Severe mechanical exposure |
The “no covering” specification reduces the wire’s per-meter cost by 15-25% compared to UL 3071 (which requires SF-2 covering). For applications where the wire is permanently installed inside a sealed equipment enclosure and won’t experience routine mechanical handling, UL 3135 provides equivalent thermal and electrical performance at lower cost.
UL 3135 in Totally Enclosed German Appliance Applications
Sealed Cooking Appliances — German manufacturers producing combi-steam ovens, espresso machines with integrated heating, and sealed steam-injection equipment for the US commercial kitchen market use UL 3135 for internal wiring inside fully sealed equipment housings. The wire is installed once at factory assembly and never accessed during service life — the sealed housing provides the mechanical protection.
Embedded Industrial Heaters — German manufacturers producing tank heaters, immersion heaters, and process heating elements for North American industrial customers use UL 3135 for the heater’s internal connection wiring. The heater body itself provides complete mechanical protection, making the covering specification unnecessary.
Hermetically Sealed Motor Equipment — German manufacturers producing hermetically sealed AC motors, compressor motors, and pump motors for US/Canadian refrigeration and HVAC equipment use UL 3135 for motor lead internal wiring. The motor’s hermetic seal provides mechanical and environmental protection for the wire throughout the motor’s service life.
UL 3135 Specifications
| Parameter | Value (per UL Subject 758) |
|---|---|
| UL Style | AWM 3135 |
| AWG Range | 26 AWG – 12 AWG, solid or stranded |
| Conductor Material | Bare or tinned copper |
| Voltage Rating | 600V AC |
| Temperature Rating | 200°C continuous |
| Insulation | Extruded silicone rubber (SR) |
| Insulation Wall | 30 mils (0.76 mm) min avg / 27 mils (0.69 mm) min at any point |
| Covering | None specified in UL listing |
| Flame Rating | Horizontal Flame per UL Subject 758 |
| Designated Use | Internal Wiring of Appliances |
| Compliance | UL Subject 758 (AWM), RoHS, REACH |
| Marking | CableApex · UL AWM 3135 · AWG · 600V · 200°C |
Engineering Notes from CableApex
- “Is UL 3135 safe to use without any covering?” Yes — within its intended application scope. The UL listing for UL 3135 was established with the understanding that totally enclosed appliance applications provide chassis-level mechanical protection. The silicone rubber itself provides electrical insulation and reasonable mechanical robustness for static internal wiring; what the covering provides in other Styles (SF-2, glass braid) is additional protection against handling, abrasion, or installation stress. For applications where the wire is installed once and remains stationary within a sealed enclosure, the silicone alone is sufficient.
- “When does UL 3135 fail to be appropriate?” Three application types should use a covered Style (UL 3071 or UL 3172) instead of UL 3135: (1) any application where the wire is routinely accessed during equipment service or maintenance, (2) wiring routed through cable carriers or articulating mechanisms where mechanical wear is expected, (3) installations with potential abrasion against chassis edges during the equipment’s vibration profile in service.
- “Cost difference vs UL 3071 at equivalent AWG?” UL 3135 typically costs 15-25% less than UL 3071 at equivalent AWG and color. The savings come from eliminating the SF-2 covering production step and material cost. For high-volume production of totally enclosed appliances, this savings is meaningful in BOM cost.
MOQ, Packaging & Shipping
MOQ varies by AWG, color combination, and production schedule. UL 3135’s wider AWG range (26-12 AWG) and simpler construction enable longer production runs and better economics than narrower-range silicone Styles. Standard packaging: spools or reels per customer specification. Export documentation: Commercial Invoice, Packing List, Certificate of Origin (CCPIT), Bill of Lading, UL Recognition reference letter, RoHS Declaration, REACH SVHC Declaration, MSDS. HS Code: 8544.49. CIF Hamburg or Rotterdam, transit time 25–30 days from Shanghai or Ningbo origin port.
Related UL Silicone Styles
UL 3135 buyers commonly cross-reference: UL 3071 (200°C / 600V silicone + SF-2 covering, 18-13 AWG — when SF-2 covering is required), UL 3122 (200°C / 300V silicone + lacquered braid, 26-16 AWG — lower voltage entry-level alternative), UL 3172 (200°C / 600V silicone + glass/aramid braid, 26-18 AWG — for severe mechanical exposure), and UL 1659 (250°C / 600V PTFE, 26-4/0 AWG — fluoropolymer alternative when temperature exceeds 200°C).
