Paper phenolic Grade XX is a thermoset laminate constructed from layers of kraft paper impregnated with phenolic resin and cured under heat and pressure into rigid phenolic sheet and rod stock. As the standard mid-tier grade in the paper phenolic family governed by NEMA LI-1, Grade XX is the most widely specified paper phenolic grade — chosen wherever consistent electrical insulation, dimensional stability, and excellent machinability are needed in switchboards, control panels, and general electrical systems.
Grade XX delivers 35,000 psi tensile strength, 34,000 psi flexural strength, and 17,000 psi compressive strength with a Rockwell M120 hardness and a water absorption of 2.00% over 24 hours. Maximum continuous operating temperature reaches 280°F (140°C). The paper phenolic laminate structure machines cleanly into terminal boards, transformer spacers, coil formers, panel inserts, and switchboard components, making xx grade the standard stock choice for electrical fabrication shops.
Standards. Grade XX is governed by NEMA LI-1. Flammability is rated 94HB per UL 94. Test methods follow ASTM D709 for laminated thermosetting materials. The XX designation is the most recognized standard-grade identifier in the paper phenolic family and appears on drawings and specs throughout the electrical industry.
Sister grades. Step down to Grade X — paper phenolic, entry-level grade when cost is the sole criterion and dielectric consistency is not critical. Step up to Grade XXX — paper phenolic, premium electrical grade when your application demands the lowest moisture absorption and highest dielectric strength in the paper phenolic family. For applications requiring mechanical toughness alongside insulation, see cotton phenolic grades.
