The Square D FA26040AB is a 2-pole, 40-amp molded case circuit breaker designed for commercial and industrial applications. Belonging to the legacy FA series, it provides reliable thermal-magnetic protection for electrical systems up to 600VAC. This F-Frame breaker installs into Square D I-Line panelboards and switchboards. It features an AB phase connection and serves as a replacement for older units. Rated at 18 kAIC at 480VAC, it includes a Visi-Trip indicator for quick fault identification.
What does the "AB" suffix mean in the FA26040AB part number?
The "AB" suffix indicates the specific phase connection for the breaker when installed in a Square D I-Line panelboard. This model connects to the A and B phases on the busbar. For other phase arrangements, you would need a breaker with an AC or BC suffix.
What type of panelboard accepts the FA26040AB circuit breaker?
This breaker is designed exclusively for Square D I-Line panelboards and switchboards. It utilizes an I-Line style plug-in connection on the line side, which mounts directly to the panelboard bus, and features standard lugs on the load side.
What is the difference between the FA26040AB, FA26040AC, and FA26040BC?
The final two letters in the catalog number dictate which phases the breaker connects to on an I-Line busbar. The FA26040AB connects to phases A and B, while the AC and BC variants connect to phases A and C, or B and C, respectively.
Can the trip settings be adjusted on the FA26040AB?
No, this breaker features a fixed thermal and fixed magnetic trip unit. While it provides both long-time and instantaneous (LI) protection functions, the trip points are factory set and cannot be adjusted in the field.
What does the LI trip function code mean on the FA26040AB?
The LI designation indicates that the thermal-magnetic trip unit provides Long-Time (L) and Instantaneous (I) protection. The long-time function protects against overloads, while the instantaneous function protects against short circuits.
Is the FA26040AB suitable for direct current (DC) systems?
Yes, in addition to its AC ratings, this thermal-magnetic breaker is rated for use in DC applications up to 250VDC, where it provides an interrupting capacity of 10kAIC.
What wire sizes are compatible with the load lugs on this breaker?
The load side lugs on the FA26040AB accept 14 AWG to 1/0 AWG copper conductors, or 12 AWG to 1/0 AWG aluminum conductors.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 70 reviews.
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Rated 5.0 out of 5 stars
Based on 70 reviews
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Reviews Summary
Generated by AI from 68 most recent customer reviews
Last updated 8/15/26
Customers say this circuit breaker matches its description, fits perfectly, and works as expected. Many reviews highlight fast shipping and quick delivery times, with several noting orders arrived within days. Users appreciate the product condition, describing refurbished units as appearing new without wear or marks. Common feedback addresses competitive pricing compared to local suppliers and the overall value proposition. Customers report straightforward ordering processes and reliable service, with repeat purchasers noting consistent positive experiences. The breaker installed easily and functioned properly in various applications.
Square D FA34030 - 30A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
9/14/26
Great company
Ordered on a Saturday evening, paid for two day shipping and it arrived on time and in perfect condition. Would 100 percent be using this company going forward, beat out pricing and shipping times for all my local supply houses. Plus the staff were great to deal with.
AH
Ann H.
Verified Buyer
Reviewing
Square D FA36100 - 100A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
8/22/26
Professional Service
So far, so good! The circuit breaker was installed along with a new compressor for our church AC, and everything is now working well.
The company has been professional, dependable, and reputable throughout the process. I had a question after the installation, and it was answered immediately. I also appreciated that they followed up and asked for feedback to make sure the new part was working properly and that we were satisfied with the service.
It’s refreshing to deal with a company that not only has quality products but also cares about its customers after the job is completed. I would definitely recommend them!
RE
rene e.
Verified Buyer
Reviewing
Square D FA34070 - 70A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
8/14/26
breaker
breaker was just as discribed
BE
Ballentine E.
Verified Buyer
Reviewing
Square D FA24060AC - 60A 2 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
7/15/26
Great
Accurate and on time.
EB
Edward B.
Verified Buyer
Reviewing
Square D FA32100 - 100A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
7/1/26
As good as new
The Square D FA32100 circuit breaker (refurbished) was as good as a new breaker, without exception. There was no wear and tear or any marks at all. It was basically new. It is an excellent choice and a great product without having to pay the cost of a new breaker.