NEMA LE

NEMA LE is the electrical-grade linen phenolic — the same fine-weave linen reinforcement as NEMA L, but manufactured to tighter controls on resin purity and paper cleanliness to meet a minimum dielectric strength of ≥350 V/mil, making it the premium linen phenolic for applications that demand both electrical insulation and smooth machined surfaces.

TL;DR

Chemistry & Reinforcement

LE phenolic shares its construction with NEMA L — fine-weave linen fabric saturated with phenol-formaldehyde resin — but adds the same resin-purity step-up that differentiates XXX from XX and CE from C:

• Reinforcement: Fine-weave linen or linen/cotton blend fabric (tighter thread count than canvas)
• Resin: Phenol-formaldehyde, minimum ionic contamination formulation
• Color/finish: Tan to light brown; noticeably smoother cross-section surface than canvas-base grades (C, CE)
• Density: ~1.30–1.36 g/cc

The finer linen weave leaves fewer exposed fiber ends at machined surfaces than canvas, which means LE phenolic achieves better surface roughness (Ra) after turning, milling, or grinding. For precision coil bobbins, relay insulators, and instrument mounting parts where both surface quality and electrical isolation matter, LE is the preferred paper/fabric phenolic.

Key Properties

Typical Applications

LE phenolic is found in applications where the engineer demands fine surface finish plus electrical isolation — often in instrument, control, and low-voltage electrical contexts:

• Precision relay bases and insulator supports — the smooth LE surface allows relay spring contacts to seat cleanly on machined faces without abrasion from glass fiber or coarse canvas texture.
• Coil bobbin and form stock — LE phenolic rod and tube are the classic coil former material for transformers and inductors in the 60–600V range. The smooth bore reduces wire insulation damage during winding.
• Instrument panel backings — linen phenolic holds tight flatness tolerances after machining; the smooth face accepts labels, scales, and engraving without texture interference.
• Electrical spacers and standoffs in test equipment — LE provides clean, predictable dielectric isolation in high-impedance measurement circuits.
• Motor end-cap insulation disks — punched or turned disks that isolate armature leads from motor housings in fractional-horsepower motors.
• Precision gear with incidental electrical isolation — instrument gear assemblies where the gear must not create a conductive path between rotating and stationary parts.

Standard Sizes

Thin sheet (1/16 in. and 1/8 in.) and small-diameter rod (1/4 to 1 in.) are the most commonly stocked forms. Large rod and tube may require custom laminator runs.

Standards Reference

1. NEMA LI 1 — Grade LE minimum requirements: dielectric strength ≥350 V/mil (1/8 in., short-time), insulation resistance, and mechanical minimums. NEMA LI 1-2020 is current.
2. MIL-I-24768/6 — Military specification, Type CFE (Cotton-fabric Fine-weave, Electrical). QPL certification required for defense programs.
3. ASTM D709 — test method standard for all laminated thermosetting materials; dielectric strength test method per D149 is the basis of NEMA LI 1 values.

Comparison to Neighbor Grades

Choose LE when: you need electrical-grade insulation with the best available surface finish from a fabric-reinforced phenolic. Choose CE when toughness (impact resistance) takes priority over surface finish. Choose L for purely mechanical parts where dielectric strength is irrelevant. Choose G3 when operating temperature or dielectric requirements exceed LE's range.

More related guides

Linen phenolic grades

• NEMA L Linen Phenolic Mechanical Grade

Compare linen to other phenolic families

• Canvas Phenolic CE Electrical Grade
• Paper Phenolic XXX Electrical Grade
• Glass Phenolic G3 Low-Cost

All grades index

• NEMA Grades Directory