Wire Harness Sleeving Selection Guide
A wire harness in an engine bay, a battery pack or a control cabinet faces a different set of killers: heat, oil and vibration in the bay; crush and abrasion in the pack; serviceability in the cabinet. There is no single sleeving that wins everywhere. This guide maps the options to the scenario.
1. Define the Real Requirements First
Before choosing a sleeving, write down four numbers and three constraints: the continuous temperature at the hot path, whether oil/chemicals/water are present, the mechanical duty (fixed vs flexing, edges, crush), and whether the harness can be serviced later. Also record one non-negotiable: EMI shielding required or not. Most failed selections come from skipping this list and jumping straight to a material.
2. The Options Compared
| Type | Heat shrink | PET braid | Self-wrapping | Zipper / woven textile |
|---|---|---|---|---|
| Install | Slide on, heat | Slide on | Wrap on | Lace / zip on |
| Seal / moisture | Yes (sealed) | No (open mesh) | No | Minimal |
| Serviceability | Cut to remove | Good | Best (rewrap) | Good |
| Abrasion | Good | Good | Good | Good-excellent |
| Flexibility | Stiff after set | Excellent | Excellent | Good |
| Temperature | Material-dependent | ~-60 to 155/180 °C | Material-dependent | To 260 °C (fiber) |
| Shielding | No (unless co-piloted) | No | No | Conductive textile only |
| Weight / space | Low | Low | Low | Medium |
3. Scenario-Based Selection
Engine bay / under-hood
Hot zones near the exhaust call for silicone-coated fiberglass or high-temperature textile. Everywhere else, oil and chafe favour a braided or self-wrapping layer. Use heat shrink only at connectors and splices where a seal matters.
Battery pack / EV
Crush, abrasion and restricted routing dominate. A flexible PET braid or self-wrapping sleeve protects the bundle; short heat-shrink seals protect connector backs. Confirm voltage creepage and dielectric if the sleeving is also an insulating barrier.
Control cabinet / panel
Serviceability is the deciding factor. Self-wrapping or zipper sleeving lets a technician open the bundle to add or trace a wire without stripping everything off. Heat shrink is used sparingly at termination points.
4. Combine Layers Rather Than Compromise
The best harnesses rarely use one sleeving. A common build is heat shrink at each connector back (seal and strain relief), a long run of PET braid or self-wrapping for chafe and bundling, and a short silicone-coated fiberglass piece in the hot zone. Deciding layer by layer beats forcing one product to do everything.
5. What to Send in Your Spec
- Harness bundle diameter and total routed length.
- Continuous and short-term temperature at the hot path.
- Fluids: oil, fuel, coolant, washdown chemistry.
- Mechanical duty: fixed, flexing, over edges, in contact with moving parts.
- Shielding requirement and how it is terminated/grounded.
- Service access needs: slide-on vs wrap-on.
Related: PET Braided Mesh Sleeve · Half-Rolling PET Braid · Self-Winding Textile Sleeve · PET Braid vs Textile Sleeving
Frequently asked questions
What is the difference between PET braided sleeving and self-wrapping sleeving?
PET braided sleeving is an open expandable mesh slid over the bundle. Self-wrapping sleeving has a slit and overlaps onto itself, so it wraps around an already-terminated harness. The choice is whether you can slide on or must wrap on.
When must I use heat shrink tubing instead of a braided sleeve?
Use heat shrink when you need a sealed, moisture-tight, mechanically tight barrier at a connector back, splice or pass-through. Use braided or woven sleeving for flexible, serviceable abrasion protection over a long bundle without needing a water seal.
How do I protect a harness against EMI / RFI?
Add a braided shielding layer (copper or tinned copper) grounded at one end; conductive textile behaves similarly. A non-conductive nylon or PET sleeve gives no shielding. State the shielding requirement separately from mechanical protection.
What sleeving is best for an engine bay under the hood?
Silicone-coated fiberglass or a high-temperature textile for hot zones near the exhaust, plus a braided or self-wrapping layer for chafe and oil. Confirm the continuous temperature at the routing path, not ambient air.
Building a harness and need the right sleeving mix?
Send the scenario, temperature, fluids and bundle OD. We return a layered protection recommendation.
Related: Browse applications · All guides