GE THQL vs THQB: Plug-In vs Bolt-On Comparison

GE manufactures two versions of their Q-Line residential/light commercial circuit breaker — the THQL (plug-in) and the THQB (bolt-on). Both have the same 10,000 AIC rating, same trip characteristics, and same amperage range. The ONLY difference is how they mount to the panel bus: THQL clips onto the bus (plug-in), while THQB bolts directly to the bus with screws. Your panel type determines which one you need.

GE THQL (Plug-In) vs GE THQB (Bolt-On) Comparison

Plug-In vs Bolt-On: What's the Difference?

The difference is purely mechanical — how the breaker attaches to the panel bus bar. A plug-in (THQL) clips onto the bus with a spring mechanism. You push it in and it snaps into place. A bolt-on (THQB) has threaded studs that bolt directly to the bus bar with nuts or screws. The electrical performance, trip characteristics, and safety ratings are identical. The mounting method is determined by your panel type.

When to Use THQL (Plug-In)

Use THQL when you have a GE residential loadcenter — PowerMark Gold, PowerMark Plus, or similar residential panels. These panels have bus bars designed for plug-in mounting. THQL is the standard residential breaker found in most GE-equipped homes. It's faster to install and remove, which is why it's preferred for residential applications where breakers may need to be swapped by homeowners or electricians.

When to Use THQB (Bolt-On)

Use THQB when you have a GE commercial panelboard — A-Series, AEF, AEU, or similar commercial panels. These panels have bus bars designed for bolt-on mounting. THQB is required in commercial applications because the bolted connection resists vibration and provides a more secure mechanical bond. It's also used in panels mounted on equipment that vibrates (HVAC units, elevator machine rooms, etc.).

Can You Use THQL in a THQB Panel (or Vice Versa)?

No. THQL breakers will NOT properly mount in a bolt-on panelboard, and THQB breakers will NOT fit in a plug-in loadcenter. The bus bar geometry is different. Attempting to force the wrong type is a code violation and creates a poor electrical connection that can arc and cause fires. Always match the breaker mounting type to your panel.

High-Interrupting Versions: THHQL and THHQB

Both THQL and THQB have high-interrupting counterparts: THHQL (22kAIC plug-in) and THHQB (22kAIC bolt-on). These are used in locations with available fault current between 10,000A and 22,000A — typically near utility transformers or in commercial buildings with large service entrances. The 'HH' in the catalog number indicates the higher AIC rating.

Verdict

THQL and THQB are the same breaker with different mounting methods. Your panel type makes the choice for you — residential loadcenters use THQL (plug-in), commercial panelboards use THQB (bolt-on). There's no quality or safety difference between them. If you're unsure which you need, look at your panel door label or check how existing breakers are mounted.

Frequently Asked Questions

Can I use a THQL in a bolt-on panel?

No. THQL plug-in breakers will not properly mount in a bolt-on panelboard. The bus bar geometry is different. Using the wrong type creates a poor connection that can arc and cause fires.

Is THQB better than THQL?

Neither is better — they serve different panel types. THQB has a more secure bolted connection (better for vibration), while THQL is faster to install/remove. The electrical performance is identical.

What's the difference between THQL and THHQL?

THHQL is the high-interrupting version with 22,000 AIC rating (vs 10,000 AIC for standard THQL). Use THHQL when available fault current exceeds 10,000A at your panel location.

How do I know if my panel takes plug-in or bolt-on?

Check the panel door label for the panel model number. PowerMark Gold/Plus = plug-in (THQL). A-Series, AEF, AEU = bolt-on (THQB). You can also look at existing breakers — if they have visible bolts/screws at the bus connection, it's bolt-on.