12.3 Splices, Taps & Terminations

12.3 Splices, Taps & Terminations

Quick Answer: All connections live under 110.14. Use devices listed for the conductors and environment; match copper vs aluminum ratings; apply 110.14(C) temperature limits when selecting ampacity columns; make splices with listed connectors inside boxes/enclosures; and torque terminations to the marked value. Loose, mixed-metal, or overheated terminations fail inspections and fail Prov stems.

On Arkansas Journeyman (Prov, NEC 2023, 60Q / 3 hr / 70%), Conductors questions often hide inside “which ampacity,” “may these be spliced,” or “aluminum feeder landing on a breaker.” Those are 110.14 questions first, cable-article questions second.

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What 110.14 covers

110.14 is the general rule for electrical connections:

• Terminals and splicing devices must provide a secure connection.
• Materials must be compatible with conductor material, insulation, and operating temperature.
• Connectors and terminals must be identified for the use (listed/labeled as required).
• Connections must be made by approved means—pressure connectors, soldering where permitted, welding, etc.—not by twisting bare copper and taping as a permanent power splice in modern practice.

Subsections you will actually open on exam day:

Exact lettering can shift by edition presentation—use your 2023 book’s headings and the index under “Connections, electrical.”

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Terminations — pressure connectors, lugs, and device screws

Listed for the conductor

Breakers, lugs, and switches are marked CU, AL, or CU/AL (or CO/ALR for certain devices). Landing aluminum on a copper-only terminal is a Code and listing violation even if the screw feels tight. For aluminum:

• Use connectors listed for aluminum.
• Follow anti-oxidant instructions when the listing/manufacturer requires them.
• Re-torque if the manufacturer specifies a practice for Al creep (field practice)—exam-wise, stress listing + torque.

One conductor per terminal (unless listed otherwise)

Most device terminals are listed for one conductor. Sticking two wires under a single breaker screw is wrong unless the terminal is identified for multiple conductors. Prov loves this workmanship trap.

Worked termination examples

Example A: 4/0 Al SER landing on a panel main lug marked CU/AL — permitted when torque and inhibitor instructions are followed.

Example B: Two 12 AWG copper wires under one receptacle screw not listed for two conductors — not permitted; use a pigtail.

Example C: Fine-strand flexible cord on a terminal listed only for building wire — may need a listed ferrule or different connector; do not force fine strand under a screw listed for Class B strand.

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Temperature limitations — 110.14(C)

This is the ampacity bridge between Article 310 and real terminations.

The default idea

Conductor ampacity used for sizing must not exceed the temperature rating of the termination. Many devices are marked 60°C or 75°C. Even if THHN insulation is rated 90°C, you often must select ampacity from the 60°C or 75°C column of Table 310.16 based on the termination rating.

NM cable interaction

Type NM-B conductors are 90°C-rated for adjustment/correction purposes inside the cable rules, but 334.80 / 110.14(C) practice typically requires ampacity to be selected from the 60°C column for NM. Exam habit: seeing “NM” + “ampacity” → think 60°C column, then apply adjustments if the stem demands them.

100 A and similar breakpoints

110.14(C) includes provisions distinguishing terminations rated for circuits 100 A or less / 14 AWG–1 AWG versus larger equipment, and when 75°C ratings may be used. Open the exact paragraphs—Prov may quote a breaker marked 75°C and ask which Table 310.16 column applies.

Example D: 3 AWG THHN copper on a 100 A breaker marked 75°C — use 75°C column ampacity (subject to other Code limits), not 90°C column for termination selection.

Example E: 12 AWG NM-B on a 20 A breaker — termination/NM rules push you to 60°C ampacity values even though the copper is THHN-type inside the cable.

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Splices — 110.14(B) and enclosure rules

Listed splice devices

Splices must use devices identified for the purpose: twist-on connectors, set-screw connectors, compression sleeves, irreversible compression taps, etc. The completed splice must be electrically and mechanically secure and insulated to a level at least equal to the conductor insulation (or enclosed so insulation is maintained).

Keep splices accessible in boxes

300.15 generally requires a box or conduit body at conductor splice points. You do not bury a wirenut in a wall cavity without an accessible box. Direct-burial listed underground splice kits are a different product category—use them only when listed for burial.

Taps vs splices on exam language

A splice joins conductors end-to-end (or in a pigtail). A tap is a conductor that taps a larger feeder/branch under Article 240 tap rules. This chapter’s installation mechanics still demand listed connectors and enclosures; the length and protection of feeder taps live in 240.21 (covered in the feeders/overcurrent chapter). If Prov asks “how long may the tap be,” leave 110.14 and open 240.21. If Prov asks “how must the connection be made,” stay in 110.14.

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Torque — 110.14 installation requirements

Where a tightening torque is marked on equipment or in instructions, terminate to that torque with a calibrated tool. Under-torque causes high resistance and heat; over-torque damages threads and conductors. Many modern stems and inspection practices treat torque as non-negotiable. Even when a numeric torque is not in the question stem, “follow manufacturer torque values” is the safe Code-aligned answer.

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Dissimilar metals and oxidation

Copper and aluminum expand differently and aluminum forms insulating oxide. 110.14 requires connectors suitable for the metals involved. Rules of thumb for stems:

• Cu-only lug + Al conductor = fail.
• Al conductor + Al/Cu-listed lug = pass when installed per listing.
• Cu pigtail + listed Al/Cu connector transitioning to Al feeder = common repair method when listed connectors are used.

Do not “solve” Al terminations by tinning with solder unless the Code and listing specifically allow that method for the device—modern pressure connectors are the expected answer.

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Common Prov traps

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Timed open-book tips

Tab 110.14, 110.14(C), 334.80 (for NM ampacity), and 300.15. Sequence for connection stems: (1) Materials compatible? (2) Device listed for Cu/Al and wire count? (3) Which temperature column does 110.14(C) force? (4) Is the splice in a proper enclosure? (5) Is the question actually a 240.21 tap-length question? That filter keeps Arkansas Prov termination items fast and accurate under the Conductors outline.