High-Temp Fiberglass Sleeving

Q: What does "Class H insulation" actually mean?
Class H is an electrical insulation rating for materials that can handle continuous exposure to 180°C, used across the cable, motor and transformer industry. This sleeving is Class H rated with a 250°C maximum, so it holds up in the hottest spots of an engine bay without breaking down.

Q: Can I use this to wrap exhaust headers or turbo piping?
No. This sleeving is rated to 200°C continuous (250°C maximum), well below exhaust manifold and turbo surface temperatures of 500°C or more. For exhaust wrap you need a purpose-built basalt or ceramic-fibre header wrap rated for that heat range. This product is for wiring and hose protection, not direct exhaust contact.

Q: What does UL 1441 (VW-1) actually mean?
UL 1441 is the safety standard covering flammability and electrical resistance of coated sleeving materials. VW-1 is the vertical flame-spread test this sleeving passes: the material self-extinguishes rather than carrying flame along its length, and it also meets UL 1441's volume resistivity requirement for electrical insulation.

Q: How flexible is it around a wiring harness?
Yes, it flexes tightly. The braided fiberglass construction bends around corners without kinking or cracking, which is why it's commonly run along wiring looms rather than just straight sections.

Q: What size do I need for my wiring bundle?
Match the internal diameter to the bundle you're covering. Undersized sleeving is a fight to pull over, oversized sleeving sits loose and protects less. Check the size guide above against your bundle's outer diameter, and round up if you're between sizes.

Q: Does it protect wiring exposed to engine oil?
It's tested for dielectric performance after oil exposure. Manufacturer data shows it retains around half of its original dielectric strength afterward, so it's not designed as a long-term oil-immersion barrier. Brief oil exposure is fine; it isn't sold as fuel-line protection, so keep it on the wiring side and use a dedicated fuel-rated line for fuel.

Q: How do I fit it and keep it in place?
Slide it over the wire or hose before you terminate the ends. It has to go on before connectors or fittings are crimped on. Once positioned, secure the ends with heat-resistant tape, cable ties or heat shrink so it doesn't ride back along the loom.

Q: Is it flame resistant on its own, or does it need extra fireproofing?
The silicone-coated fiberglass braid is self-extinguishing under the UL 1441 VW-1 test, so it won't carry a flame along the sleeve. It's a protective layer for the wiring underneath, not a substitute for correctly rated cable insulation.

Q: What's the minimum and maximum temperature it handles?
Continuous use is rated from -40°C to 200°C, covering everything from a cold start to sustained engine bay heat, with a maximum (short-term) rating of 250°C for hot spots.

Q: How is it sold, and can I order odd lengths?
Sold per metre in each diameter. Order the exact length you need for the run, cut to size.