Class 105 Paper-Covered Bare Round Copper Wire is a type of electrical magnet wire that consists of a bare round copper conductor insulated with multiple layers of high-quality insulating paper.
Insulating Material:
The insulating material shall be rope paper, Kraft paper, or both. The paper covering shall be one or more tape layers wrapped firmly, closely, evenly, and continuously around the wire.
Thermal Class: 105 impregnated or in oil. The thermal class of fibrous-covered or paper tape–wrapped wire shall be based on experience.
For wire having two or three layers (N) and tape thickness of 0.051 or 0.076 mm.
Copper Conductor Diameter:
| AWG Size | Mandrel Size |
| 8-32 AWG | Min：0.201mm-3.231mm |
| Nominal: 0.203mm-3.264mm | |
| Max: 0.206mm-3.287mm |
Adherence And Flexibility:
No openings sufficient to expose the bare conductor when wound on the following mandrel:
| AWG Size | Mandrel Size |
| 8-13.5 | 5d |
| 14-22.5 | 4d |
| 23-32 | 3d |
No openings sufficient to expose the bare wire after elongation as follows:
| AWG Size | Elongation Method |
| 8-13.5 | 15% (+2, -0) |
| 14-22.5 | 10% (+2, -0) |
| 23-24 | 8% (+2, -0) |
Elongation: Not less than 24%
Springback: Not greater than 5º
Dielectric Breakdown: Paper-covered bare wire constructions: no requirement.
The class 105 paper-covered bare round copper wire is commonly used in transformers, motors, and other electrical devices where high-performance insulation and thermal resistance are required.