Split Bolt vs C-Tap vs Insulated Multi-Tap (Polaris): Which Tap Connector to Use by Conductor, Location and Code
Sep 10, 2026
Summary: A split bolt is a reusable mechanical tap listed to UL 486A/B, for above-grade copper or aluminum taps that must be taped or covered; it is not permitted buried or encased. A C-tap is an irreversible compression tap listed to UL 486A and, for grounding, UL 467, used where the joint will never be opened and, in the grounding versions, where it is buried or in concrete. An insulated multi-tap (the Polaris type) is a pre-insulated set-screw block listed to UL 486C at 600 V, for gutter and box splices where a finished, touch-safe joint is required with no taping. Pick by whether the joint is buried, whether it will be opened again, and whether it must be insulated.
The three connectors
| Split bolt | C-tap (compression) | Insulated multi-tap | |
|---|---|---|---|
| Type | Mechanical, bolt and spacer, reusable | Irreversible compression, crimped with a die | Set-screw block in molded insulation, reusable |
| Listing | UL 486A/B (CU or AL9CU) | UL 486A/B; grounding types also UL 467 and IEEE 837 | UL 486C, 600 V, AL9CU |
| Insulation | None; tape or a listed cover required on power conductors | None; tape on power, none on grounding | Built in, touch-safe, 600 V, 90 C |
| Buried or in concrete | No | Yes, when marked UL 467 Direct Burial | No (some are listed for direct burial when marked; most are not) |
| Conductor | Copper or dual-rated; run and tap of different sizes | Copper; run and tap ranges per die | Copper or aluminum, per port range |
| Tool | Wrench | 12-ton crimper and matching die | Hex key or screwdriver, torque per marking |
| Can be reopened | Yes | No | Yes |
| Typical cost, 2/0 run | Low | Low to medium plus tooling | Medium |
Where the code puts each one
- Grounding electrode conductor splices, buried or in concrete: NEC 250.64(C) requires irreversible compression or exothermic welding. C-tap, marked 467 DB. Split bolts and multi-taps are not permitted.
- Grounding electrode conductor taps above grade, accessible: 250.64(D) allows listed connectors; a split bolt or a bronze C-tap both qualify; most inspectors prefer compression.
- Equipment grounding conductors in boxes and panels: 250.148 requires listed connectors; split bolt, C-tap or multi-tap all acceptable; multi-tap where several EGCs land in a gutter.
- Feeder and branch circuit splices and taps (power): 110.14(B) requires devices identified for the use and insulation equivalent to the conductors. A split bolt or bare C-tap needs tape or a listed cover to 600 V; an insulated multi-tap is complete as installed. In a gutter, wireway or a 240.21 tap, the multi-tap is the finished answer.
- Service entrance conductors in a meter base or CT cabinet: utility rules apply; many require compression or insulated multi-taps and prohibit split bolts.
- Aluminum conductors: any of the three if marked AL9CU; apply oxide inhibitor; never a copper-only split bolt on aluminum.
Selection by job
| Job | Use | Why |
|---|---|---|
| Tap a 4/0 copper service ground to a 6 AWG water pipe bond, in the panel | Split bolt 4/0 to 6, or C-tap | Accessible, grounding, no insulation needed |
| Splice a buried 4/0 GEC to a ground ring | C-tap UL 467 DB | 250.64(C), irreversible only |
| Tap a 3/0 feeder in a gutter for a subpanel | Insulated multi-tap, 2-port, 250 kcmil to 6 | Finished 600 V insulation, reopenable, 240.21 tap |
| Parallel three 500 kcmil feeders at a busway | Insulated multi-tap, 4-port, or two-hole compression lugs | Multiple conductors per phase, torque documented |
| Temporary power tap on a job site | Split bolt, taped | Comes apart at the end of the job |
| Solar array grounding from module clip to bar | C-tap or split bolt, bare | Grounding, above grade, no insulation |
| Generator transfer switch neutral splice | Insulated multi-tap | Inspector sees a listed insulated joint |
| Extending a cut 2 AWG copper in a wall, not accessible | Not permitted with any of these; splice must be in an accessible box (300.15) |
Installation notes
Split bolt: brush conductors, place the run and tap on opposite sides of the spacer, tighten to the marked torque (typically 60 to 300 lb-in by size), then insulate with rubber splicing tape followed by vinyl, or a listed split-bolt cover, to a thickness equal to the conductor insulation. Re-torque is not required; re-taping is if it is opened.
C-tap: match the die to the run and tap combination marked on the connector; the run sits in the deep groove, the tap in the shallow. Crimp once for standard C-taps, twice for long-body. For grounding, no insulation. For power, tape as for a split bolt.
Insulated multi-tap: strip to the port depth marked on the body, insert fully so no bare conductor shows at the port, torque each screw to the value on the label, replace the screw caps. Single-side and dual-side entry versions exist; dual-side lets the run pass through without cutting.
Quick answers
Can a split bolt be buried? No. Buried grounding connections require irreversible compression or exothermic weld per NEC 250.64(C); use a UL 467 DB C-tap.
Does a split bolt need to be taped? On power conductors, yes, to the insulation level of the conductors; on bare grounding conductors, no.
Is a Polaris connector the same as a multi-tap? Polaris is NSi's brand name for insulated multi-tap connectors; the generic term is insulated multi-tap or insulated splice block, listed to UL 486C.
Can I reuse a C-tap? No. It is an irreversible compression connector; cut it out and crimp a new one.
Conversions Tech stocks split bolts 10 AWG to 500 kcmil, UL 467 C-taps and Figure 6 and 8 connectors, and insulated multi-taps 14 AWG to 750 kcmil in 1 to 4 ports, all with cross-references to Burndy, Ilsco and Polaris part numbers. See the die chart for C-tap crimping and the torque chart for multi-tap screws.
