Complete guide to the Leviton LB120-2T 20-Amp Combination AFCI Circuit Breaker
The Leviton LB120-2T is a 20-amp, single-pole Combination Arc Fault Circuit Interrupter (CAFCI) breaker designed to detect dangerous arcing conditions in branch circuit wiring before they ignite a fire. It meets National Electrical Code (NEC) requirements for AFCI protection in bedrooms, living rooms, hallways, and most other habitable areas of a home, making it a go-to choice for new construction, panel upgrades, and code-driven renovations.
Below we break down what the LB120-2T does, where it fits, how it installs, and how to evaluate it against alternatives so you can decide whether it belongs in your load center. For a hands-on evaluation, see our full Leviton LB120-2T review.
Quick verdict
A reliable, code-compliant AFCI for Leviton load centers
If you have a Leviton residential load center and need a 20-amp single-pole AFCI breaker, the LB120-2T is a straightforward, dependable pick. It combines parallel and series arc-fault detection with a self-test feature and a clear trip indicator, making troubleshooting and code inspections easier.
Key specifications
| Feature | Value |
|---|---|
| Model | Leviton LB120-2T |
| Type | Combination AFCI (CAFCI) |
| Amperage | 20 A |
| Poles | 1-pole |
| Voltage | 120 V AC |
| Interrupting rating | 10,000 AIC |
| Compatibility | Leviton load centers (plug-on) |
| Self-test | Yes, with status LED indicator |
| Trip indication | Visible trip flag / LED |
| Certifications | UL 1699 listed |
What a Combination AFCI actually protects against
Standard circuit breakers protect against overloads and short circuits, but they cannot detect the low-current arcing that often starts inside damaged cords, loose terminations, or stapled-through cables in walls. A Combination AFCI like the LB120-2T monitors current waveforms and trips when it identifies signatures of:
- Parallel arcing — arcs between hot and neutral or hot and ground.
- Series arcing — arcs along a single conductor, such as at a broken wire strand or loose screw terminal.
- Overloads and short circuits — traditional thermal-magnetic protection is still included.
Why "combination" matters: The word refers to the breaker's ability to detect both parallel and series arc faults, which is the level of protection currently required by the NEC for AFCI-protected circuits.
Where the LB120-2T fits in your panel
Compatibility
This breaker is designed specifically for Leviton residential load centers. It will not mechanically or electrically interchange with Square D, Eaton, Siemens, or GE panels. If you have a different panel, consider the Eaton BRCAF115 Combination AFCI or the Square D HOM115PCAFI Plug-On Neutral AFCI instead. Before ordering, confirm:
- Your panel is a Leviton load center (look for the Leviton branding inside the dead front).
- You have an open 1-inch breaker space on the bus.
- The circuit you are protecting is 20 A or less, 120 V single-phase.
Typical applications
- Bedroom receptacle and lighting circuits
- Living rooms, family rooms, dens, dining rooms
- Hallways, closets, and recreation rooms
- Kitchens and laundry areas where dual AFCI/GFCI is not required (use a dual-function breaker there instead)
Who should buy it
Required by NEC for most 15- and 20-amp, 120-V branch circuits in dwellings.
When replacing a Leviton load center or moving from standard to AFCI-protected circuits.
Extending or modifying existing branch circuits may trigger AFCI requirements per local code.
The LED indicator helps electricians quickly identify the cause of past trips.
Installation overview
Installation should be performed by a licensed electrician or a competent DIYer who is comfortable working inside an energized load center. Always follow the instructions packaged with the breaker and verify the panel is de-energized before working in it.
- Turn off the main breaker and verify no voltage at the bus with a non-contact tester and a meter.
- Remove the dead front cover.
- Connect the branch circuit hot conductor to the breaker's LOAD terminal.
- Connect the branch circuit neutral to the breaker's LOAD NEUTRAL terminal.
- Connect the breaker's pigtail (panel neutral) to the neutral bar in the load center.
- Snap the breaker onto the bus stab in an open slot.
- Reinstall the dead front, restore power, and press the TEST button to verify proper operation.
Shared neutrals: AFCI breakers require a dedicated neutral for each protected circuit. Multi-wire branch circuits sharing a neutral will cause nuisance tripping unless a two-pole AFCI is used.
Pros and cons
Strengths
- Meets current NEC CAFCI requirements
- Self-test feature simplifies code-mandated periodic testing
- LED trip indicator speeds diagnosis
- UL 1699 listed with 10,000 AIC interrupting rating
- Compact 1-inch footprint fits standard Leviton load centers
Limitations
- Only compatible with Leviton load centers
- Provides AFCI only — does not include GFCI protection
- More expensive than a standard 20 A breaker
- Can nuisance-trip with certain motor loads or shared neutrals
LB120-2T vs. similar options
| Feature | LB120-2T (AFCI) | Dual-Function AFCI/GFCI | Standard 20 A Breaker |
|---|---|---|---|
| Arc fault protection | Yes | Yes | No |
| Ground fault protection | No | Yes | No |
| Overload/short circuit | Yes | Yes | Yes |
| Typical use | Bedrooms, living areas | Kitchens, laundry, mixed areas | Garages (where permitted), legacy installs |
| Relative cost | Moderate | Higher | Lowest |
Tip: If a circuit needs both AFCI and GFCI protection (such as a dishwasher circuit in many jurisdictions), choose a dual-function breaker rather than the LB120-2T. For GFCI-only needs in a Siemens panel, the Siemens QF120 20-Amp GFCI breaker is a solid option.
Troubleshooting nuisance trips
If the LB120-2T trips repeatedly, work through these checks before assuming the breaker is faulty:
- Check for shared neutrals — each AFCI needs its own dedicated neutral conductor.
- Inspect terminations — loose backstabs and over-stripped wires create series arcs.
- Unplug everything and reset — then add loads one at a time to isolate the offending device.
- Look for damaged cables — staples driven too tight, drywall screws, or rodent damage in walls.
- Verify the LED indicator — the blink pattern after a trip indicates the type of fault detected; consult the Leviton documentation that ships with the breaker.
Frequently asked questions
Is the LB120-2T required by code?
The NEC requires Combination AFCI protection on most 15- and 20-amp, 120-volt branch circuits in dwelling units. The LB120-2T satisfies that requirement when installed in a compatible Leviton load center, but always check your local amendments.
Can I use it in a Square D, Eaton, or Siemens panel?
No. AFCI breakers are not interchangeable between manufacturers. The LB120-2T fits only Leviton load centers. Using it in another brand's panel is unsafe and not UL listed.
Does it also provide GFCI protection?
No. The LB120-2T is an AFCI-only breaker. For combined arc-fault and ground-fault protection, choose a dual-function (AFCI/GFCI) model from the Leviton lineup.
How often should I test it?
Manufacturers and the NEC recommend testing AFCI breakers monthly using the TEST button. The breaker should trip immediately; reset it by pushing the handle fully off, then back on.
Can I install it myself?
If you are comfortable working safely inside an energized panel and your jurisdiction allows homeowner electrical work, yes. Otherwise, hire a licensed electrician — mistakes inside a load center can be fatal.
Why does my AFCI trip when I plug in a vacuum or power tool?
Brushed motors and some switching power supplies can produce signatures similar to arcing. Try a different outlet on a different circuit; if the appliance trips multiple AFCIs, the device itself may need service.
Bottom line
The Leviton LB120-2T is a solid, no-frills Combination AFCI breaker for anyone running a Leviton load center. It checks the boxes that matter most: UL 1699 listing, a 10,000 AIC interrupting rating, a usable self-test feature, and clear trip diagnostics. If your application also needs ground-fault protection, step up to a dual-function model; otherwise, the LB120-2T delivers code-compliant arc-fault protection without unnecessary complexity.
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