Both are fabric-backed electrical tapes with a black cloth look, and they are routinely confused. They are not interchangeable: Acetate Cloth Tape is an insulation tape for windings, while PET cloth tape is an abrasion and bundling tape for harnesses.
Where they differ
| Property | Acetate Cloth Tape | PET cloth tape |
|---|---|---|
| Primary purpose | Electrical insulation | Abrasion protection and bundling |
| Surface | Smooth, thin, conformable | Textured woven fabric, tougher |
| Typical use | Coils, transformers, motors | Wiring harness, conduit wrapping |
| Key strength | Dielectric strength, moisture and mildew resistance | Abrasion class, noise damping, hand-tear options |
| Typical thickness | Thin, for fitting between winding layers | Around 0.25 mm for standard harness grade |
Specify acetate cloth tape when
The tape is part of the insulation system. Layer insulation in a transformer, coil wrapping in a motor, and end-turn insulation all rely on dielectric strength that stays stable when humidity rises. Acetate cloth also conforms to curved coil ends without lifting, which matters when a winding is built by hand.
Specify PET cloth tape when
The tape has to survive mechanical abuse. Harness tape is judged on abrasion class, temperature and — inside a vehicle — noise damping. PET polyester fabric carries a class D abrasion rating in the standard 0.25 mm harness grade, and the range includes both non-tearable versions for maximum protection and hand-tearable versions for speed.
The overlap, and how to resolve it
There is one genuine grey area: bundling leads inside a motor or a transformer. Here both tapes can work. The question to ask is whether the tape is providing insulation between conductors, or just holding them together. If it is between conductors, use acetate cloth tape and specify the dielectric requirement. If it is holding a bundle together inside a housing, a PET cloth tape is usually cheaper and more resistant to abrasion.
Do not mix them up in a drawing
Because both are black cloth tapes, a bill of materials that says only “black cloth tape” is an open invitation to substitute the wrong one. Write the base material (polyester acetate cloth or PET polyester fabric), the thickness and the performance requirement into the drawing.
Tapes mentioned in this guide: C8020 acetate cloth tape · B1300 / B1600 PET cloth tape
