Machined Arc Chutes
Arc chutes are the most demanding machined thermoset components in low- and medium-voltage switchgear: they must withstand the violent thermal and mechanical shock of fault-current arcing while maintaining their geometry precisely enough to direct and extinguish the arc safely. Material selection, dimensional accuracy, and surface condition all directly affect the performance and UL/ANSI listing of the assembly they go into.
Federal Materials machines arc chute components and arc barriers to customer prints in the thermoset grades specified by the major switchgear OEMs: G10, FR4, canvas phenolic (CE), and GPO-3. We hold complex profiles — vented sections, angled baffles, interlocking tabs — to the tight tolerances that switchgear design demands. Every arc chute order ships with material certification and is available with dielectric testing.
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- Arc chute side plates — profiled, slotted, and vented plates in pairs or assemblies
- Arc runners and arc horns — contoured guides for arc elongation
- Baffles and deionizing plates — interlocking or stacked configurations
- Interphase barriers — phase separation in three-phase assemblies
- Arc chute housings — complex milled profiles with multiple features
- Circuit breaker arc barriers — molded-profile complements machined from laminate
- Contactor arc guards — small-form factor, tight tolerance
- MCC (motor control center) arc barriers — IEC and NEMA configurations
- Custom prototype arc components — from print or sample, fast turnaround
Material Selection for Arc Chutes
| Material | Key arc property | Notes |
|---|---|---|
| G10 (Epoxy-Glass) | High tracking resistance, structurally stiff | Standard for general MV switchgear |
| FR4 (Epoxy-Glass, FR) | UL94 V-0 flame rating | Required when flammability listing is specified |
| CE Phenolic | Good arc resistance, economical | Paper and canvas phenolic used in legacy designs |
| GPO-3 | Superior arc resistance, FR polyester | Arc-track resistant by design; MIL-I-24768 Type GPO-3 |
G10 vs. FR4 for arc chutes: FR4 adds the UL94 V-0 brominated flame retardant; G10 does not. For new switchgear designs requiring UL listing, FR4 is typically specified. G10 is used in non-UL and legacy designs. Never substitute one for the other without engineering approval.
Typical Tolerances
| Dimension type | Production tolerance |
|---|---|
| Profile dimensions (CNC milled) | ±0.005" |
| Critical slot and tab features | ±0.003" |
| Plate flatness | ±0.005" per 12" |
| Thickness | ±0.003" |
| Hole location | ±0.003" |
Arc chute components often have complex profiled features — angled slots, relief pockets, interlocking tabs — that require 3- and 4-axis CNC milling. All features are programmed from DXF/DWG or STEP files. Submit your CAD file with your RFQ for fastest response.
Finish Options
| Finish | Description |
|---|---|
| As-machined | Standard for G10 and FR4 arc chutes — clean, deburred, edges broken |
| Hot oil dip | Standard for phenolic arc chutes — seals surfaces, protects from tracking initiation |
| Edge chamfering | Profiles chamfered or radiused per drawing — reduces field-intensification at sharp edges |
| No coating | Do not apply adhesives, paints, or coatings to arc-chute surfaces without engineering approval |
Standard Turnaround
| Stage | Lead time |
|---|---|
| Quote response | Same business day (standard RFQs with CAD file) |
| Prototype / first article (1–5 pcs) | 5–10 business days |
| Short run (5–50 sets) | 10–15 business days |
| Production run (50+ sets) | 15–25 business days |
Arc chute components often involve complex programs and multi-step setups. Submit your CAD file (STEP/DWG/DXF) at time of RFQ for the fastest turnaround.
Materials We Stock (Arc Chute Stock Shapes)
| Material | Form | Sizes | Notes |
|---|---|---|---|
| G10 | Sheet, plate | 0.062" – 2.000" thick; up to 48" × 96" | NEMA GP03 |
| FR4 | Sheet, plate | 0.062" – 2.000" thick; up to 48" × 96" | NEMA FR4, UL94 V-0 |
| CE Phenolic | Sheet, plate | 0.062" – 3.000" thick | NEMA LI-1 CE |
| GPO-3 | Sheet, plate | 0.125" – 1.000" thick | MIL-I-24768, arc-track resistant |
GPO-3 is a glass mat-reinforced polyester with purpose-designed arc-track resistance and flame retardancy — distinct from the epoxy-based fiberglass grades. Call for current GPO-3 availability.
Quality & Inspection
- Dimensional inspection — full profile inspection to drawing; CMM or vision system for complex profiles
- Dielectric withstand testing — hipot and tracking resistance testing available (specify test voltage and method)
- Material certification — NEMA grade, UL file reference (FR4), or MIL-I-24768 (GPO-3)
- Visual inspection — edge condition, slot and tab condition, delamination check
- Hot oil dip log — phenolic parts: oil temperature and immersion time per batch
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