Insulation Material:
The fiber cover shall be a combination of polyester and glass fibers. The glass fibers shall be electrical grade continuous filament glass yarns. The polyester fibers shall be high grade yarns produced by the linear polymerization of ethylene glycol and terephthalic acid. The maximum polyester fiber content in the yarn shall not exceed 50% by weight.
Characteristic:
| Adhesion and flexibility: | Single or Dual Layer with Primer: No visible cracks in the film insulation after 20% elongation. Inspect with normal vision without removal of the polyester fiberglass cover. Dual Layer Unprimed Film: Minimum thickness of the polyester fiberglass cover on one side not less than 75 V/mil (2950 V/mm) Note: Minimum thickness of the polyester fiberglass cover is 35% of the maximum dimension incrementRectangle: Table 14 |
| Elongation | 32% or more for thicknesses 0.049 inches (1.25 mm) and above 30% or more for thicknesses less than 0.049 inches (1.25 mm) |
| Springback | Polyester fiberglass covered bare wire: not more than 5ºPolyester fiberglass covered thick film insulation: not more than 5.5º |
Dielectric breakdown
Dielectric Breakdown, Film-Insulated Rectangular and Square Magnet Wire
| Film Insulation | Minimum Breakdown Voltage | |
| Any Three of Four Values | Fourth Value | |
| Heavy | 1500 | 500 |
| Quad | 2500 | 900 |
Table 14
| Nominal Width of Conductor (inches) | Increase in Dimensions (Inches) | ||||||
| Polyester Glass Fiber Covering Over Rectangular Bare Copper Conductor | |||||||
| Single Coveringof Polyester Glass Fiber | Double Coveringof Polyester Glass Fiber | ||||||
| Over | Up To and Incl. | Min. | Nom. | Max. | Min. | Nom. | Max. |
| – | 0.114 | 0.0040 | 0.0045 | 0.0050 | 0.0080 | 0.0095 | 0.0110 |
| 0.115 | 0.144 | 0.0040 | 0.0045 | 0.0050 | 0.0080 | 0.0100 | 0.0120 |
| 0.144 | 0.182 | 0.0050 | 0.0055 | 0.0060 | 0.0090 | 0.0110 | 0.0130 |
| 0.183 | 0.229 | 0.0050 | 0.0060 | 0.0070 | 0.0100 | 0.0120 | 0.0140 |
| 0.230 | 0.289 | 0.0050 | 0.0060 | 0.0070 | 0.0110 | 0.0130 | 0.0150 |
| 0.290 | 0.517 | 0.0060 | 0.0070 | 0.0080 | 0.0110 | 0.0135 | 0.0160 |