Compression Splices: Sizing, Installation & Burndy/Panduit Cross-Reference Guide
Apr 20, 2026
Every inline wire join in a NEC-compliant installation needs a splice — and the splice you choose determines the quality of that connection for the life of the installation. Compression splices create a permanent, gas-tight, low-resistance joint that won't loosen, corrode, or fail under load.
Compression Splices vs Mechanical Splices vs Wire Nuts
There are three ways to join two wires inline. Here's why compression wins for permanent installations:
- Compression splices: Cold-welded barrel creates a gas-tight seal. Zero resistance increase. Permanent. Rated for direct burial. Used in utility, industrial, and commercial installations where failure is not an option.
- Mechanical splices (split bolts): Reusable and field-adjustable. Good for temporary connections and situations where you need to disconnect later. Higher resistance than compression.
- Wire nuts: Fastest to install. Residential-grade. Not suitable for high-vibration, outdoor, or high-current applications. Can loosen over time.
When to Use Compression Splices
Compression splices are the right choice when you need a permanent, low-resistance inline connection. Common applications include:
- Service entrance and feeder splicing — joining conductors in pull boxes and junction boxes
- Underground and direct burial — splices rated for wet locations and soil contact
- Solar string extensions — joining PV wire runs between combiner boxes
- Panel board connections — extending conductors to reach terminals
- Motor and generator leads — high-vibration environments where mechanical connections can loosen
- Utility distribution — overhead and underground primary/secondary splicing
Sizing Your Splice
The splice barrel must match the conductor size on both ends. For same-size conductors, use a standard barrel splice. For different sizes (reducing splice), use a stepped barrel that accommodates both gauges. Common sizes we stock:
- #8 AWG through 4/0 AWG — standard copper compression splices
- 250 MCM through 750 MCM — large conductor splices
- Reducing splices for step-down connections (e.g., 2/0 to #2)
All our compression splices are tin-plated copper with color-coded die marks that match industry-standard crimping tools (Burndy, Panduit, Thomas & Betts die compatibility).
Insulated vs Bare Splices
Bare compression splices require separate insulation — typically heat-shrink tubing or rubber splicing tape. For faster installations, our insulated splices come pre-insulated with nylon or heat-shrink tubing that seals the connection in one step.
For underground or wet locations, always use heat-shrink splices with adhesive-lined tubing for a waterproof seal.
CT Splices vs Burndy and Panduit
Our compression splices are direct replacements for the Burndy YS series and Panduit SCS series. Same specifications, same UL listing, same die compatibility — at 70-85% lower cost.
| Size | CT Price | Burndy YS | Panduit SCS | You Save |
|---|---|---|---|---|
| #6 AWG | $1.85 | $8.50 | $9.25 | 78-80% |
| #2 AWG | $2.45 | $11.00 | $12.50 | 78-80% |
| 1/0 AWG | $3.14 | $14.50 | $15.75 | 78-80% |
| 4/0 AWG | $4.85 | $19.00 | $21.50 | 74-77% |
| 250 MCM | $6.50 | $25.00 | $28.00 | 74-77% |
Tools You Need
Compression splices require a hydraulic or mechanical crimping tool with the correct die set. Our ProCrimp 12-Ton hydraulic crimper ($328.90 vs $2,299 Greenlee) handles all standard compression splices from #8 AWG to 750 MCM. Color-coded crimping dies are available separately for $54.99 each.
Installation Best Practices
- Strip to the mark: Each splice barrel has a strip-length indicator. Strip exactly to that mark for a full-depth insertion.
- Center the conductor: The conductor should be visible through the inspection window (if present) or centered in the barrel.
- Match the die: Use the die index number stamped on the splice barrel. Using the wrong die creates an under-crimped or over-crimped connection.
- Crimp from center out: For long-barrel splices, crimp the center first, then work outward to each end.
- Insulate after crimping: For bare splices, apply heat-shrink tubing or rubber splicing tape rated for the installation voltage.
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