Key Differences Explained

1. Temperature Rating — UL 3135 Has a 20°C Advantage

UL 3135 is rated 200°C continuous — 20°C higher than the 180°C rating of standard VDE H05SS-F and H07SS-F silicone wire. This 20°C margin is operationally significant in high-temperature appliance internal wiring where wire surface temperatures approach the insulation ceiling. For motor lead applications in Class H insulation motors (180°C maximum winding temperature), UL 3135 at 200°C provides a 20°C safety margin above the maximum winding temperature — a margin that VDE 180°C-rated silicone wire does not provide. In practice, this means UL 3135 can be specified for Class H motor lead applications without temperature derating, while VDE H07SS-F at 180°C is operating at its thermal ceiling in the same application.

2. Voltage Rating — UL 3135 Consolidates in One Rating

UL 3135 carries a single 600 Vac rating covering all conductor sizes from 26–12 AWG. VDE silicone wire splits into two designations by voltage: H05SS-F at 300/500V and H07SS-F at 450/750V — requiring the engineer to select the correct designation for the circuit voltage. For three-phase 480V motor lead applications, H07SS-F (450/750V) is the correct specification — H05SS-F at 300/500V does not provide adequate voltage rating margin. UL 3135 at 600V covers both single-phase and three-phase motor lead applications without this designation split.

3. “Totally Enclosed” Use Classification — Important for UL Compliance

UL 3135’s UL use classification specifies “internal wiring of appliances where totally enclosed” — meaning the wire must be protected within a sealed or enclosed appliance enclosure, not exposed to external mechanical damage or environmental contact. VDE H05SS-F and H07SS-F have a broader use classification covering general appliance and equipment internal wiring without the “totally enclosed” restriction. For UL product certification audits, the “totally enclosed” condition of UL 3135 must be satisfied — wire routed in open conduit or exposed positions inside partially open equipment enclosures may require a different UL Style such as UL 3071 with fiberglass braid outer covering.

4. Conductor Flexibility — VDE Specifies Finer Stranding

VDE H05SS-F and H07SS-F specify Class 5 flexible stranded conductor — fine individual strands for maximum flexibility. UL 3135 permits solid or stranded conductor without specifying maximum strand count, resulting in less fine stranding in practice. For motor lead applications where the wire must be routed through tight bend radii inside motor end shields and terminal boxes, VDE Class 5 conductor flexibility may be superior to standard UL 3135 stranded conductor at equivalent cross-section. For static appliance internal wiring where the wire is routed once and does not flex in service, this difference is not operationally significant.

5. Insulation Wall Thickness — Similar in Practice

UL 3135 specifies 30 mils (0.76mm) minimum average insulation wall. VDE H05SS-F and H07SS-F specify 0.6mm minimum. The UL 3135 wall is approximately 27% thicker than the VDE minimum — resulting in a slightly larger overall wire outer diameter at equivalent conductor cross-section. For applications where routing space is at a premium, VDE silicone wire’s thinner insulation wall produces a more compact wire profile. For UL AWM applications, the 30-mil wall is the certified standard and cannot be reduced.