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Grey Siemens three-pole bolt-on breaker 40 A 240 V AC toggle switch

SIEMENS

SIEMENS BQ3B040 circuit breaker 40 A 240 V AC 3-pole bolt-on

SKU CH-R5QM-CF0QQ

Three-pole bolt-on breaker rated 40 A at 240 V AC with 10 kA interrupting capacity for Siemens panelboards

  • 40 A three-pole protection for 240 V AC circuits
  • 10 kA interrupting rating handles high fault currents
  • Bolt-on mounting fits Siemens panelboards directly
  • Lug terminals accept 8 AWG to 4 AWG aluminium or 6 AWG copper
  • Operates up to 104 °F in a 125 A frame

Purpose and fit

The Siemens BQ3B040 is a three-pole miniature circuit breaker rated at 40 amps and 240 volts AC. It is designed for bolt-on installation in compatible Siemens panelboards and protects three-phase circuits in residential or light commercial settings.

Capacity and limits

The breaker carries a maximum AIR rating of 10 kA at 240 volts AC and fits a 125 amp frame size. It accepts copper wire from 8 AWG to 6 AWG and aluminium wire from 8 AWG to 4 AWG. Operation is rated up to 104 degrees Fahrenheit and it has no DC voltage rating.

Mounting and accessories

The unit uses a bolt-on mounting style with lug terminals for secure panelboard connection. No additional accessories or software are included in the package. The toggle actuator provides manual switching and trip indication.

How it compares

Measured against everything we stock in Breakers & Circuit Protection, at today’s prices. Recalculated every night.

Price $447.99
Pricier than about 90% of the 1,135 comparable items (median $54.99).

Specifications

Product
Brand nameSiemens
Model nameBQ3B040

Questions about this item

Will the BQ3B040 bolt-on breaker fit alongside older Siemens BQ-series breakers in the same panelboard?

Yes, the BQ3B040 uses the same bolt-on mounting style and BQ frame size 125A, so it installs directly into compatible Siemens panelboards that accept BQ-series breakers.

How can I verify the 40 A, 240 V AC, 3-pole breaker is operating correctly after installation?

Switch the toggle actuator to the on position and confirm the circuit carries load without tripping; the breaker should remain latched up to its 10 kA interrupting rating at 240 V AC.

Does the BQ3B040 come with terminal lugs, or must I purchase wire connectors separately?

The breaker includes a terminal connection lug that accepts 8 AWG to 4 AWG aluminium or 6 AWG copper wire, so no separate lugs are required for conductors within that range.

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