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ASME B107.37-2003 — Pliers: Wire Cutters/Strippers
✂️ ASME B107.37-2003 is a substandard of the ASME B107 family, Hand Tools and Accessories, that provides performance and safety requirements for wire strippers and for the cutting and stripping functions of multipurpose tools used on solid and stranded copper wire. It may be used as a guide by state authorities or regulatory bodies in formulating laws or regulations, and is intended for voluntary use by establishments that use or manufacture the covered tools — from electrical wiring and electronic assembly to telecommunications and appliance repair. The Standard references ASME B46.1 (surface texture), ASME B107.25 (Pliers — Performance Test Methods), and MIL-W-16878 (high-temperature insulated electrical wire).
💡 Stripping is essentially “cut the insulation without cutting the conductor”: the blade depth must match the insulation thickness. The Standard defines blade sizes and capacities around exactly that trade-off — reliable insulation cutting without damaging the copper core.
1. Scope and Classification 📌
The Standard provides performance and safety requirements for stripping and cutting on solid and stranded copper wire, classified as follows:
- Type I — Wire strippers, pivoting handles:
- Class 1 — general-purpose insulation: for ordinary PVC-type insulation.
- Class 2 — polytetrafluoroethylene (Teflon) insulation: for MIL-W-16878 Types E and EE wire.
- Type II — Wire cutters/strippers, flat jaws and handles:
- Class 1 — small frame, strippers forward of pivot, nonadjustable (spring and lock optional).
- Class 2 — large frame, strippers forward of pivot.
- Class 3 — large frame, strippers rear of pivot.
- Class 4 — small frame, strippers forward of pivot, adjustable size (spring and lock optional).
| Type / Class | Construction | Applicable Wire | Typical Applications |
|---|---|---|---|
| Type I, Class 1 (general insulation) | Pivoting handles, sized stripping holes | PVC and general insulation copper wire | Electrical wiring, general stripping |
| Type I, Class 2 (Teflon insulation) | Pivoting handles, hard-insulation profile | MIL-W-16878 Types E/EE Teflon wire | Aerospace, high-temperature cable |
| Type II, Class 1 (small frame, nonadjustable) | Flat jaws, strippers forward of pivot | Small-to-medium solid/stranded copper | Electronic assembly, appliance repair |
| Type II, Class 2/3 (large frame) | Flat jaws, strippers forward/rear of pivot | Larger copper gauges | Building wiring, distribution work |
| Type II, Class 4 (small frame, adjustable) | Flat jaws, adjustable stripping size | Multiple gauges | Mixed multi-gauge jobs |
2. Technical Requirements: Blade Sizes and Capacities 📏
The tables define blade sizes and capacities for each class:
- Type I, Class 1 blade sizes and capacities: the wire gauge range (AWG) for each stripping hole and the cutting capacity.
- Type I, Class 2 blade sizes and capacities: hole sizes and cut-in depth for hard insulations such as Teflon.
- Type II blade sizes and capacities: the cutting capacity (maximum copper wire gauge) of the flat-jaw tools and each stripping position.
In addition, handle load, jaw surface roughness (per ASME B46.1), and related characteristics are constrained so feel and cutting performance stay consistent.
⚠️ The stripping hole and wire gauge must match: an oversized hole fails to cut the insulation and forces a second operation; an undersized hole cuts into the copper core, nicking the conductor, which breaks easily under bending or vibration. Always verify the gauge (AWG or mm²) against the stripping hole before use.
3. Test Methods and Performance Verification 🔬
Section 6 defines the test procedures:
- Handle load test: apply the loads specified in Table 4 to the handles; the tool must not fail or sustain significant permanent deformation, and cutting/stripping functions must remain normal.
- Cutting test: cut solid and stranded copper wire of the specified gauges to verify cutting capacity and edge quality.
- Stripping test: strip specimens of the specified gauge and insulation type, verifying clean insulation cuts with no conductor damage.
- Dimensional and surface checks: verify blade-hole sizes against the tables and jaw/blade surface roughness per B46.1.
💡 For acceptance, do a “three strips, three cuts” spot check: strip the smallest and largest rated specimens and check for a clean insulation cut with no conductor nicks; after cutting, check for a square cut and intact edges.
4. Safety Requirements and Limitations of Use 🛠️
- 🔍 Electrical safety: strippers and cutters are often used on or near live cables; confirm the insulated handles are intact and meet the applicable electrical safety requirements, and never work on unidentified cables while energized.
- 🔧 Gauge matching: select the stripping hole/cutting position by wire size; never force heavy wire through small holes or cut above the rated capacity.
- 📊 Edge care: clean and protect edges after use; never cut steel wire, nails, or other hard objects with the cutting edges.
- 📋 Inspection and replacement: stop using and replace tools with chipped edges, loose pivots, or damaged insulated handles.
🚨 Multi-purpose cut-and-strip tools are safe only when each function is used correctly: using the stripping position as a cutter damages the edge, and using the jaw as a stripper nicks the conductor. Using the marked function positions correctly is the basic prerequisite for electrical work safety.
5. Frequently Asked Questions ❓
❓ Q: How do I choose between Type I and Type II tools?
A: Type I is a dedicated stripper with high stripping quality and a full range of holes — best when stripping dominates; Type II is a cut-and-strip combination — best for multi-purpose work needing frequent cutting and stripping.
A: Type I is a dedicated stripper with high stripping quality and a full range of holes — best when stripping dominates; Type II is a cut-and-strip combination — best for multi-purpose work needing frequent cutting and stripping.
❓ Q: Why is Class 2 specifically for Teflon insulation?
A: Teflon (PTFE) insulation is hard and springy; ordinary stripping holes cannot cut it cleanly and easily damage the conductor. The Standard therefore defines separate blade sizes and capacities for MIL-W-16878 Types E/EE wire to ensure reliable stripping.
A: Teflon (PTFE) insulation is hard and springy; ordinary stripping holes cannot cut it cleanly and easily damage the conductor. The Standard therefore defines separate blade sizes and capacities for MIL-W-16878 Types E/EE wire to ensure reliable stripping.
❓ Q: How does stripping stranded wire differ from solid wire?
A: Stranded wire is made of many thin filaments that are prone to broken strands or nicked filaments during stripping, making it more sensitive to hole size and cut-in depth. The Standard covers both, and you should verify capacity against the actual wire construction.
A: Stranded wire is made of many thin filaments that are prone to broken strands or nicked filaments during stripping, making it more sensitive to hole size and cut-in depth. The Standard covers both, and you should verify capacity against the actual wire construction.
🔍 Q: Why does the Standard emphasize “performance and safety” over detailed dimensions?
A: Following B107 practice, this edition is performance-based: as long as the handle load, cutting, and stripping functions pass the prescribed tests, the product conforms; the size tables mainly define capacity boundaries for each class rather than constraining design details.
A: Following B107 practice, this edition is performance-based: as long as the handle load, cutting, and stripping functions pass the prescribed tests, the product conforms; the size tables mainly define capacity boundaries for each class rather than constraining design details.
