A single-pole breaker is a type of circuit breaker that controls one energized (hot) wire and provides 120V protection to a single branch circuit in residential panels. It's commonly used for lighting and outlet circuits rated at 15 or 20 amps.

When wiring a standard single-pole AFCI (Arc Fault Circuit Interrupter) breaker, four key wires are involved, but only three connect directly to the breaker: hot, neutral from the circuit, and pigtail from the breaker. The fourth, a ground wire, connects to the panel’s ground bar, not the breaker.

Properly wiring an AFCI breaker enables the breaker’s arc fault detection function.

Why Wiring Matters for AFCI Protection

An AFCI breaker doesn’t just trip on short circuits or overloads. It actively monitors the current travelling through both the hot and neutral wires. If it detects an abnormal waveform, it immediately cuts power.

For this to work, the breaker needs:

• A hot wire delivering current to the load,

• A neutral wire returning that current through the breaker (not bypassing it),

• A connection to the panel’s neutral bus bar via its built-in pigtail to complete the internal monitoring circuit.

Wire Breakdown and Functions

1. Black (Hot/Load Wire)

• Connects to: Load terminal on the AFCI breaker

• Connects directly to the breaker

This wire delivers current from the panel to the devices (receptacles, lights) on the branch circuit. It’s the power source for everything downstream.

2. White (Neutral Wire from the Circuit)

• Connects to: Neutral terminal on the AFCI breaker

•Connects directly to the breaker

This conductor carries return current back through the breaker. It must not be landed on the panel’s neutral bar. Connecting it incorrectly disables the AFCI’s sensing loop and leaves the arc detection ineffective.

3. White Pigtail from the Breaker (Factory-Installed)

• Connects to: Neutral bus bar in the panel

• Pre-attached to the breaker; you connect the free end

This pigtail ties the breaker into the panel’s grounded system and powers its internal electronics. It must be secured to the neutral bus bar with an open terminal.

4. Bare or Green Ground Wire (from the Circuit)

• Connects to: Ground bus bar in the panel

• Does NOT connect to the breaker

This safety conductor provides a low-resistance path for fault current. It has no interaction with the breaker’s arc detection, but it’s still required for electrical code compliance.

What Cable Is Used to Wire AFCI Circuits?

In most residential applications, NM-B (non-metallic sheathed cable), commonly known as Romex, is used for AFCI-protected branch circuits. This cable type includes hot, neutral, and ground conductors bundled in a single sheath and is suitable for indoor use in dry locations. It has all the required conductors and is a NEC choice for indoor residential use.

Common sizes of cables for AFCI circuits are 14/2 for 15-amp AFCI breakers, 12/2 for 20-amp AFCI breakers, and 12/3 for shared-neutral setups with two AFCI breakers or a handle-tied tandem breaker in multi-wire branch circuits.