Square D: keep QO and Homeline separate.

Quick answer

• Square D: "The Square D QO and Homeline load centers are UL tested, listed, and labeled to accept ONLY Square D circuit breakers." [Q1]
• Square D, on its own breakers in other panels: QO breakers "are only UL tested and approved for use in QO, NQO, NQOD, and NQ panelboards" [Q3]. "The Homeline branch breakers are NOT classified to be used in competitors load centers." [Q2]
• Eaton sells UL Classified Type CHQ for Square D QO loadcenters and Type CL for Square D HOMELINE loadcenters [E12 p.102, p.103].
• Siemens describes Type QD as "UL Classified for use in place of Square D Type QO circuit breakers in Square D load centers" [S4 p.1].
• ABB lists Type TQ as "3/4" UL Classified Circuit Breakers for use in *Square D **QO Load Centers." [G4 p.1-57]
• Square D's warranty bulletin states: "Schneider Electric disclaims all liability for damage, injury or non-performance caused by the use or failure of incompatible or UL® classified circuit breakers." [Q4 p.1]

Compare a printed dimension, not an installation permission. Equal width does not establish a listed or classified combination.

Eaton CH3/4 in. per poleE5 p.5

Eaton BR1 in. per poleE5 p.5

Eaton CL1 in. per poleE12 p.103

Eaton CHQ3/4 in. per poleE5 p.8

Square D QO3/4 in. per poleQ7 p.67

Square D Homeline1 in. per poleQ7 p.67

Siemens QP1 in. per poleS9 p.1

Siemens QD3/4 in. per poleS9 p.47

GE / ABB THQL1 in. per poleG1 p.1

GE / ABB THQP1/2 in. per poleG1 p.1

Original drawing and source annotations

The original drawing is schematic, not a product label, field measurement or installation instruction.

Open the original full-size SVG

"½" THQP"; ABB not accepting new orders as of October 2, 2024

Sources: E5 Eaton Residential Product Guide MZ00400002E p.5, p.8; K5 Eaton KB 000015509; E12 Eaton CA08100002E (2022) p.103; E1 Eaton IL00304001Y p.1; Q6 Square D 0730CT9801 p.3;

Q7 Square D 1100CT0501 pp.45, 67; S9 Siemens SPEEDFAX SF-17 pp.1, 47; S4 Siemens QD brochure p.1; G1 ABB THQP notice (June 28, 2024) p.1. The panel label governs.

QO and Homeline: how Square D describes them

Square D's 2026 catalog compares the two load center lines in its Table 51 [Q7 p.67]:

The row label beside the breaker descriptions reads "UL Listed Only for Square D Circuit Breakers" [Q7 p.67]. The Homeline section repeats it: "UL Listed Only for Square D Breakers: 1-in. format breakers trip to center position." [Q7 p.45]

QO and QOB breakers

• "QO (plug-on) and QOB (bolt-on) one-, two- and three-pole thermal-magnetic circuit breakers provide overcurrent protection and switching on ac and dc systems." [Q6 p.3]
• Where each type is used [Q6 p.3]:
  • "Plug-on QO circuit breakers are for use in QO load centers, NQ and NQOD panelboards, OEM mounting bases, and Speed-D® switchboard distribution panels." [Q6 p.3]
  • "Bolt-on QOB circuit breakers are for use in NQO and NQOD panelboards." [Q6 p.3]
• Standards: "QO and QOB circuit breakers are built to comply with UL Standard 489, CSA 22.2 No. 5, NOM/ANCE and NEMA Standard AB1". "QO circuit breakers are UL Listed under UL File E84967." [Q6 p.3]
• Voltage ratings listed: "120 Vac", "208/120 Vac", "120/240 Vac", "240 Vac" and "48 Vdc (10–70 A for 1 and 2 pole circuit breakers, 10–60 A for 3 pole circuit breakers)" [Q6 p.4].
• Trip indication: "When the circuit breaker has tripped, the handle assumes a center position and the red Visi-Trip indicator appears in a window in the circuit breaker case." [Q6 p.3]

Plug-on / bolt-on

Square D’s document names QO as plug-on and QOB as bolt-on. Q6 p.3

CTL / Non-CTL

The Eaton drawings distinguish a notched bus stab and rejection tab from an unnotched stab. The replacement conditions are in the document. E12 pp.78, 83

Simplified shapes for terminology only. No installation sequence or dimensional fit is shown.

Original drawing and source annotations

The original drawing is schematic, not a product label, field measurement or installation instruction.

Open the original full-size SVG

1968".

Sources: Q6 Square D 0730CT9801 (2008) p.3; Q3 Square D FAQ FA124299; E12 Eaton CA08100002E (Nov 2022) pp.78, 83; S9 Siemens SPEEDFAX SF-17 p.45. Schematic only; it does not show

how to install anything.

QO branch breakers by interrupting rating (Table 1)

Source: [Q7 p.8]. The table also lists QO-HID, QO-PL, QO-PLILC, QO-SWN, QO-VHGFI and QOB-VH [Q7 p.8].

Homeline branch breakers (Table 32, all 10,000 AIR)

Source: [Q7 p.47].

QOT: two descriptions in the same catalog

The 2026 catalog describes QOT tandems in two ways [Q7 pp.6–8]:

Square D's own statements on other makers' breakers

• "The use of any other manufacturers' breakers, will VOID the UL listing and warranty of the product." [Q1]
• "Square D disclaims all liability for damage, injury or non-performance caused by the use or failure of non-Square D circuit breakers." [Q1]
• "NO. The Homeline branch breakers are NOT classified to be used in competitors load centers. Also, the use of the branch breakers in competitors load centers is NOT authorized by Square D." [Q2]
• "No, the QO breakers are only UL tested and approved for use in QO, NQO, NQOD, and NQ panelboards." [Q3]
• The residential warranty bulletin disclaims "all liability for damage, injury or non-performance caused by the use or failure of incompatible or UL® classified circuit breakers" [Q4 p.1].

Other makers' UL Classified breakers for Square D panels (shown beside Square D's statements)

Eaton's list sets these conditions: "EATON Type CL, CL GFCI & CL AFCI circuit breakers have been Classified by UL® for use in place of UL listed circuit breakers in UL listed panelboards/meter centers." "CAUTION: If the application requires breakers to be handle-tied, both Classified breakers must be the same manufacturer and type." The supply system is "Single-Phase, 3-Wire, 120/240 V~ Max. Available Short Circuit Current 10 kAIC". [E1 p.1]

Square D recalls and counterfeit notices

• 2022: QO Plug-on-Neutral load centers "manufactured between February 2020 and January 2022, with date codes between 200561 and 220233" [C8].
• 2004: QO and Homeline AFCI breakers "manufactured after March 1, 2004" with "a blue test button" and red date codes CN–JN [C7].
• 2002: MA/MH breakers "manufactured between October 2000 and March 2002" [C12].
• 1988: Series 1 two-pole GFCI breakers with "a yellow 'Push-To-Test' button" [C11].
• 2006–2010: five distributor recalls of counterfeit "Square D" QO/QOB breakers [C5] [C6] [C14] [C15] [C16]. Genuine breakers have:
  • "the amp rating written on the handle in white paint on the front of the breaker" [C16];
  • "the Square D insignia molded onto the breaker side" [C16];
  • "a yellow chromate mounting clip with half of the top of the clip visible" [C16].
  • The same notice adds that "authentic Square D circuit breakers manufactured prior to 2003 did not have white paint on the amperage numbers" [C16].

Original outline drawing (not a photo, not to scale). Feature wording is quoted from CPSC recall notices for counterfeit "Square D" breakers.

Front1

Side2 · 3 · 4

1 Amp rating on the handle

"the amp rating written on the handle in white paint

on the front of the breaker" (C5, C14, C15, C16).

C16 adds: "authentic Square D circuit breakers

manufactured prior to 2003 did not have white paint

on the amperage numbers".

2 Molded insignia

"the Square D insignia molded onto the breaker side"

(C5, C14, C15, C16).

3 Mounting clip

"a yellow chromate mounting clip with half of the

top of the clip visible" (C14, C15, C16; C5 says

"yellow chromate clip").

4 Arc chute opening (one notice)

"on the side of the breaker, where wire terminal

screw is located, the arc shoot opening should have

squared corners with the bottom edge of the opening

angled up" (C6).

CPSC: "If your breaker does not match this description, it could be counterfeit." (C5) CPSC tip: "Look for a certification mark from an independent testing

organization, such as Underwriters Laboratories (UL), and the manufacturer's label." (C9)

These historical notice descriptions are not a standalone authenticity test. Keep the applicable notice and its product/date scope. C16

Original drawing and source annotations

The original drawing is schematic, not a product label, field measurement or installation instruction.

Open the original full-size SVG

Sources: CPSC recall notices C5 (Miami Breaker, Aug 2, 2010), C6 (Scott Electric, Nov 16, 2006), C14 (Connecticut Electric, Oct 30, 2007), C15 (North American Breaker

Co., Dec 27, 2007), C16 (Specialty Lamp International, May 27, 2008); C9 CPSC counterfeit warning (May 2007). C16 remedy: "Consumers should contact Specialty to

determine if the breaker they have is counterfeit".

What to bring to an electrician

• The load center catalog number and date code from inside the door [C8] [Q7 p.33].
• The breaker list on the wiring diagram: "Square D circuit breakers that may be used in this load center" [Q7 p.34, p.60].
• If a classified breaker is proposed: the matching IL00304001Y page and its conditions [E1 p.1] or the QD listing [S4 p.2], together with Square D's statements above [Q1] [Q4 p.1].

Sources

All documents fetched 2026-11-15 or 2026-11-16 and archived with SHA256 (see SOURCE-LIBRARY.csv). Kind: primary = issued by the manufacturer/agency; primary-mirror = manufacturer document hosted by a third party; primary (vendor) = issued by the maker of the replacement product described.

Related reference photographs