XXX High-Humidity Paper Phenolic (NEMA XXX) — Sheet

NEMA Grade XXX is the premium electrical paper phenolic laminate — a thermoset composite of high-quality kraft paper impregnated with phenolic resin. It delivers 35,000 psi tensile strength, the highest dielectric strength in the paper phenolic family, and the lowest moisture absorption at just 0.57% over 24 hours. Grade XXX is governed by NEMA LI-1 and is preferred for power distribution components, transformer spacers, switchgear parts, and other demanding electrical applications.

Grade XXX is the premium electrical tier; Grade XX is the standard tier. The critical differentiator is moisture absorption and dielectric performance: XXX absorbs only 0.57% moisture vs. 2.00% for XX, which directly translates to more stable and reliable dielectric performance in humid or electrically stressed environments. For switchboards and general control panels, XX is sufficient; for power distribution, transformers, and higher-demand electrical systems, XXX is the appropriate specification.

Ready Plastics stocks Grade XXX paper phenolic in sheet and rod form. XXX rod stock is popular for machined transformer components and electrical bushings. Cut-to-size is available on all paper phenolic sheet and rod SKUs — contact us or see the product page for current size inventory and minimum order details.

Yes. Grade XXX machines cleanly on conventional mill, lathe, drill press, and router equipment with standard carbide tooling. It holds good dimensional tolerances and accepts drilled and tapped features without chipping. Use sharp tooling, moderate feed rates, and dust extraction. As with all paper phenolic grades, XXX is more brittle than cotton phenolic and is not suitable for applications involving significant impact loading.

No. Grade XXX uses kraft paper as reinforcement; CE and LE use woven cotton fabric. Cotton fabric provides substantially higher impact strength and mechanical toughness — making CE and LE the right choice for components that experience shock or sustained mechanical load. Grade XXX is optimized for electrical insulation performance: lower moisture absorption and higher dielectric strength than any cotton phenolic grade. Choose XXX for demanding electrical insulation; choose CE or LE when you need precision machining with both electrical and mechanical performance.