Supplying reliable power distribution, this 125A Siemens MCCB is tailored for commercial facilities. It utilizes thermal-magnetic trip technology with fixed LI functions. The unit mount breaker installs into Siemens P1, P2, and P3 panelboards and meter centers. This legacy QJ series model is replaced by the QR23B125. Rated for 10kAIC at 240VAC, the three-pole device features a non-interchangeable trip and is reverse feed rated for versatile applications.
This bolt-on breaker is designed for installation in Siemens P1, P2, and P3 panelboards, as well as compatible switchboards and meter centers. Note that installation requires the correct breaker mounting kit, which varies depending on whether you have an Original or Revised generation panelboard.
Is the QJ23B125 obsolete or replaced by a newer frame?
The QJ frame is a legacy series that has been superseded by the Siemens QR frame. The direct replacement for this specific breaker is the QR23B125, which provides the same dimensions, mounting style, and electrical ratings.
Can the QJ23B125 be used in reverse-feed applications?
Yes. The breaker is constructed with a non-interchangeable trip unit, making it suitable and UL approved for reverse-feed installations.
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Reviews
Review summary
Customers rate this product 4.8 out of 5 based on 10 reviews.
Siemens QJ23B125 - 125A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
9/11/26
Breaker
Perfect
TN
Timothy N.
Verified Buyer
Reviewing
Siemens QJ23B200 - 200A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
7/27/26
10% off
Arrived on time, worked when turned on
WK
Willie K.
Verified Buyer
Reviewing
Siemens QJ23B150 - 150A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 4 out of 5 stars
7/22/26
Breaker
The Breaker arrive fast and in good condition however when I looked at the specs it was not the correct one.
PG
Phil G.
Verified Buyer
Reviewing
Siemens QJ23B200 - 200A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
3/3/26
Great Service
I was in a bind for this breaker that was for an elevator, and Nick got me all the components even though their blizzard! Will use them for all my specialty breakers.
VC
Vladimir C.
Verified Buyer
Reviewing
Siemens QJ22B200 - 200A 2 Pole Molded Case Circuit Breaker
I recommend this product
Rated 4 out of 5 stars
12/10/25
4 start
The breaker was it perfect match.,but it was missing the two top bolts.