XX Phenolic Sheet — Thicknesses, Sizes & Stock Forms
XX phenolic sheet is flat laminate plate stock produced from NEMA Grade XX paper phenolic: layers of kraft paper saturated with phenolic resin and compression-molded into rigid thermoset sheet. Ready Plastics stocks XX phenolic sheet as the cost-effective choice for switchboards, control panel substrates, terminal boards, and general electrical insulation where lightweight construction, good machinability, and reliable dielectric properties are needed without the premium of glass-fabric or linen grades. NEMA LI-1 governs Grade XX.
At a glance:
- Thickness range: 0.020" to 4.0"
- Standard sheet size: 48" × 96" (4 ft × 8 ft); cut-to-size available
- Flatness tolerance: per NEMA LI-1; thickness tolerance ±10% standard
- Material: NEMA Grade XX — kraft-paper phenolic laminate (NEMA LI-1)
- Production method: Compression-molded thermoset laminate
- Color: Natural tan to light brown
Standard Thickness Table
XX phenolic sheet is stocked in the following standard thicknesses:
| Thickness | Sheet Size | Notes |
|---|---|---|
| 0.020"–0.062" | 48" × 96" | Thin sheet for gaskets and shim stock |
| 0.093" (3/32") | 48" × 96" | Light panel and barrier stock |
| 0.125" (1/8") | 48" × 96" | Standard switchboard panel stock |
| 0.250" (1/4") | 48" × 96" | Control panel and terminal board |
| 0.375" (3/8") | 48" × 96" | Structural insulating plate |
| 0.500" (1/2") | 48" × 96" | Heavy panel and bus support |
| 0.750" (3/4") | 48" × 96" | Thick insulating plate |
| 1.000"–4.000" | 48" × 96" | Thick plate for machined components |
Cut-to-size is available on all thicknesses; minimum order is one piece.
Mechanical & Electrical Properties
XX phenolic sheet carries the NEMA Grade XX property set per NEMA LI-1:
| Property | Value |
|---|---|
| Tensile strength | 35,000 psi (240 MPa) |
| Flexural strength (LW, 0.125") | 34,000 psi (230 MPa) |
| Compressive strength | 17,000 psi (115 MPa) |
| Shear strength | 11,500 psi (79 MPa) |
| Bond strength | 1,500 psi (10 MPa) |
| M-scale hardness | 120 |
| Izod impact strength at 49 °C (LW) | 0.80 ft·lb/in |
| Specific gravity | 1.35 |
| Water absorption (24 hr) | 2.00% |
| Flammability | UL 94HB |
| Max. operating temperature | 280 °F (140 °C) |
XX sheet's high flexural strength (34,000 psi) and high compressive strength (17,000 psi) are notable for a paper-based grade — the paper laminate is stiffer than cotton-reinforced grades in bending, making it well-suited for panel substrates under mechanical load. The maximum operating temperature of 280 °F (140 °C) exceeds cotton phenolic grades CE and LE.
Typical Applications
- Switchboard panels and backplanes — XX sheet has historically been the standard material for residential and commercial switchboard panel construction where cost-effective insulation is required
- Control panel substrates — Flat, dimensionally stable XX sheet accepts drilled and milled cutouts for switches, relays, and terminal blocks in industrial control cabinets
- Terminal boards and strips — XX sheet punches and drills cleanly to form precision terminal boards with consistent insulation resistance between conductors
- Bus-bar supports and spacers — High compressive strength (17,000 psi) resists bus-bar clamping loads without creep deformation
- Low-voltage transformer insulation — Layer-wound paper phenolic sheet provides inter-winding and turn-to-turn insulation in distribution transformers
- General electrical fixture panels — Cost-effective sheet stock for light fixtures, outlet boxes, and residential wiring device mounting plates
Machining XX Phenolic Sheet
XX phenolic sheet saws easily on circular saws, band saws, and CNC routers with standard carbide blades; the paper-base construction cuts cleanly with less fiber tear-out than woven-fabric grades. Use positive-hook carbide blades and a backer board on drill-through operations. The material routes and mills to clean edges suitable for panel cutouts and mounting slot patterns. High compressive strength (17,000 psi) means the sheet does not compress under drill point pressure, delivering accurate hole locations without pre-drilling. Phenolic dust is abrasive — use dust extraction and respiratory protection throughout.
Related
- XX Phenolic Grade Line Card
- XX Phenolic Rod — round bar stock for turned switchboard pins and insulator blanks
- XX Phenolic Tube — hollow section for insulating sleeves and conduit liners
- XXX Phenolic — higher-grade paper phenolic for elevated dielectric requirements