Does this arc fault breaker manage one or two circuits?

Question

I recently tested our breakers to see what was mapped to what. In the process of doing this, I noticed that our arc fault breaker is handling a LOT. Specifically:

• 4 bedrooms
• 2 bathrooms
• Family room
• Attic light
• Dining room ceiling light.

It's unclear to me whether or not it's managing a single circuit or two. I see two "15s" on the switch lever... so... so does that mean that there's actually two 15 amp circuits connected to it?

That would make more sense considering the load (still not ideal but certainly more reasonable than having EVERYTHING on a single 15 amp circuit).

Here's a picture:

Answer 1

That is a two-pole AFCI breaker. Two-pole breakers will disable both poles when a fault is detected. It is likely that they are connected in a "shared-neutral" configuration, which is considered a single circuit. Half of the loads (outlets, lights, etc) would be connected to L1 while the other half of the loads are connected to L2. Even though the two hot wires share only one neutral wire, they can safely handle the same amount of power as two 15 A circuits with two neutral wires. Shared neutrals reduce the overall amount of wiring used (especially useful for long runs), but slightly increases the complexity of the wiring in the house.