NEMA CE

NEMA CE is the electrical-grade canvas phenolic — woven cotton canvas impregnated with phenolic resin and manufactured to tighter electrical-property controls than the mechanical NEMA C grade, delivering a laminate that combines the impact toughness of canvas reinforcement with meaningful electrical insulation performance.

TL;DR

Chemistry & Reinforcement

CE phenolic uses the same fundamental construction as NEMA C — woven cotton canvas impregnated with phenol-formaldehyde resin — but the resin formulation and paper-selection controls are tightened to minimize ionic contamination that reduces insulation resistance.

• Reinforcement: Plain-weave woven cotton canvas
• Resin: Phenol-formaldehyde, compounded for reduced ionic content (higher purity than Grade C)
• Color/finish: Dark brown; canvas weave visible on cross-section
• Density: ~1.30–1.35 g/cc

The cotton canvas weave provides the characteristic high impact toughness of the canvas family (roughly 2–4× paper phenolic), while the tighter resin controls push dielectric strength from the ~200–350 V/mil range of Grade C up to the ≥350 V/mil minimum of CE. This dual performance profile is the reason CE phenolic appears wherever a part must function simultaneously as a structural member and an electrical insulator.

Key Properties

Typical Applications

CE phenolic occupies a unique application space: parts that must provide electrical insulation while withstanding significant mechanical loads or impact:

• Structural insulation panels in switchgear — mounting frames and subpanels in medium-voltage switchgear where bus bars carry current across a structural member that must resist racking loads.
• Transformer coil form mandrels — the coil form must support winding tension (mechanical) while isolating primary from secondary (electrical).
• Motor brush holders — canvas phenolic is classic brush-holder stock: machinable, tough enough to retain the spring-loaded brush, and electrically isolated from the motor frame.
• Arc chute side walls (low-voltage) — in 600V-class circuit breakers and contactors where the side wall must withstand arc energy and also be a housing insulator.
• Machined insulating standoffs — standoffs that both fasten and isolate bus bars in transformer junction boxes.
• Control panel sub-panels with field-machined cutouts — where an electrician in the field cuts custom openings and the canvas construction machines cleanly without fragmenting.

Standard Sizes

CE phenolic sheet in 1/8–1/2 in. is the most commonly stocked range. Thicker sections (1 in. and above) are available but may require longer lead times from laminators due to longer press cycles.

Standards Reference

1. NEMA LI 1 — Grade CE is defined with specific minimums for dielectric strength (≥350 V/mil, 1/8 in., short-time) and insulation resistance, in addition to the mechanical minimums of Grade C. NEMA LI 1-2020 is the current edition.
2. MIL-I-24768/4 — Military specification Type CBE (Cotton-fabric-Base, Electrical). QPL certification required for defense procurement.
3. ASTM D709 — master test standard for laminated thermosetting materials; test methods for dielectric strength referenced in NEMA LI 1.

Comparison to Neighbor Grades

Choose CE when: you need canvas-level toughness plus a meaningful electrical insulation barrier — the most balanced canvas phenolic grade. Choose C when electrical properties are irrelevant and maximum machinability is the goal. Choose LE when finer surface finish (from finer linen weave) is required on machined faces. Choose G3 when temperature exceeds 250°F or much higher electrical strength is needed.

More related guides

Canvas phenolic grades

• NEMA C Canvas Phenolic Mechanical Grade

Compare canvas to other phenolic families

• Linen Phenolic L Grade
• Linen Phenolic LE Electrical Grade
• Paper Phenolic XXX Electrical Grade
• Glass Phenolic G3

All grades index

• NEMA Grades Directory