GPO-3 Glass Polyester Laminate (also known as Red Barrier Board or Glastic®) is a high-performance fiberglass-reinforced thermoset laminate. Manufactured by impregnating fiberglass mats with polyester resin and curing under heat and pressure, it delivers excellent arc resistance, UL 94 V-0 flame retardancy and reliable mechanical strength. Complying with NEMA GPO-3 standards, it is widely used for busbar insulation, switchgear parts and high-voltage system components. Available in sheets, rods, and custom machined parts for electrical insulation and structural support.
Excellent dielectric & electrical insulation
High arc, tracking and CTI resistance
UL 94 V-0 flame retardant performance
High heat resistance and mechanical stability
Outstanding dimensional stability & low moisture absorption
Great chemical and varnish resistance
Highly machinable, suitable for punching & custom parts
| Properties | Value | Unit |
| Mechanical properties | ||
| Density | 1.9 | g/cm³ |
| Flexural strength perpendicular | 130 | N/mm² |
| Flexural modulus of elasticity | 9000 | N/mm² |
| Compressive strength perpendicular | 250 | N/mm² |
| Tensile strength | 70 | N/mm² |
| Impact strength parallel tolaminations | 40 | kJ/m² |
| Water absorption | <0.2 | % |
| Thermal properties | ||
| Temperature endurance (Temperature index) | 155 | T.I |
| Working temperature class F | 155 | ℃ |
| Flame resistance | FVO>3mm | UL94 |
| Thermal conductivity | 0.3 | W/mK |
| Electrical properties | ||
| Dielectric strength at 90℃in oil perpendicular | 23 | kV/mm |
| Dielectric strength at 90℃ in oil parallel | 47 | kV/mm |
| Creep voltage strength | 600 | CTI |
| Insulation resistance after immersion in water | 5×10⁸ | Ω |
GPO-3 is widely used in electrical, industrial, and power distribution systems, thanks to its excellent arc resistance, dielectric strength, and flame-retardant properties. Typical applications include:
1. Busbar insulation barriers
2. Arc chutes and arc barriers
3. Switchgear insulation panels
4. Electrical panelboard backers
5. Terminal blocks and standoffs
6. Transformer coil supports
7. Motor control center panels
8. Mounting brackets and structural supports
9. Insulating spacers and washers
10. Arc flash isolation panels
Although GPO-3 and FR4 are both fiberglass laminates, they are engineered for different working conditions.
GPO-3 provides outstanding arc resistance, lower water absorption, better heat resistance and easier machining.
It is more suitable for high‑voltage switchgear and power distribution insulation, while FR4 is mainly used for general electronic insulation.
To select the suitable GPO-3 material for your project, please refer to the following points:
If you are unsure about the specification, feel free to contact us for professional recommendations.
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