Circuit Breakers: Square D vs Eaton vs Siemens vs GE
Head-to-head comparison of residential (QO, BR, QP, THQL) and commercial (Powerpact, Series C, Sentron, Spectra) breaker lines — interrupting rating, arc-flash rating, panel compatibility, and where each brand actually wins.
Four brands own residential and commercial circuit-breaker distribution in North America: Square D, Eaton, Siemens, and GE. PES Distribution stocks all four in authorized-channel inventory — meaning the AIC label on the breaker matches the manufacturer's actual rating, warranty registration works, and tech support routes to the factory. This guide is a spec-out comparison across the residential 1-inch lines (QO, BR, QP, THQL) and the commercial molded-case lines (Powerpact, Series C, Sentron, Spectra) so a contractor pulling a takeoff can lock in the right brand for the panel, the utility, and the interrupting-rating requirement.
The residential 120/240 V single-phase 1-inch breaker market is a four-horse race. Each brand ships a value tier and a premium tier. What matters at spec time is (a) which load center you're feeding it into — breakers are not universally interchangeable across brands, and (b) whether the branch circuit needs standard, AFCI, GFCI, or combination dual-function (DFCI) protection under NEC 210.8 and 210.12.
| Brand | Line | Value / Premium tier | AIC (240 V) | AFCI / GFCI / DFCI catalog |
|---|---|---|---|---|
| Square D | QO | Premium (tighter tolerance, 1-inch) | 10 kAIC (22 kAIC on QOB) | QO120CAFI (AFCI), QO120GFI (GFCI), QO120DF (DFCI) |
| Square D | Homeline (HOM) | Value | 10 kAIC | HOM120CAFIC (AFCI), HOM120GFIC (GFCI), HOM120DFC (DFCI) |
| Eaton | BR | Value (1-inch) | 10 kAIC (22 kAIC on BJ) | BRLAF120 (AFCI), BRLGF120 (GFCI), BRLAFGF120 (DFCI) |
| Eaton | CH | Premium (3/4-inch — more spaces / inch) | 10 kAIC (22 kAIC on CHB) | CHFCAF120 (AFCI), CHFGFT120 (GFCI), CHFAFGF120 (DFCI) |
| Siemens | QP | Standard 1-inch | 10 kAIC (22 kAIC on BQD) | Q120AF (AFCI), Q120GFP (GFCI), QAF2020 (DFCI) |
| GE | THQL | Standard 1-inch | 10 kAIC (22 kAIC on THHQL) | THQL1120AF2 (AFCI), THQL1120GF (GFCI), THQL1120DF (DFCI) |
⚠ Panel compatibility is not universal — a QO breaker will not seat safely in a Homeline load center.
Square D QO and Homeline use different bus stab geometry. Same with Eaton BR vs CH, and Siemens QP vs QT. The only UL-listed cross-brand interchangeable line is Eaton BR interchangeable with GE THQL and Siemens QP in specific classified applications (UL 67 / UL 489, Eaton catalog series 'CL'). Do not assume interchangeability from a physical fit — verify the panelboard label and the UL classification card.
Ordering a residential AFCI/GFCI/DFCI panel — the shortcut PES contractors use
- Whole-panel bundle order — PES pre-bundles combination AFCI, GFCI, and DFCI breakers by load-center part number. Enter the Square D QO140M200PC main breaker load center, and the tool returns a bill of materials for the 40 branch circuits (AFCI kitchens/bedrooms, GFCI bathrooms/laundry, DFCI garage) at contractor pricing.
- Same tool for Eaton BR/CH, Siemens P4/QP, and GE PowerMark/THQL panelboards. Turnaround from click to PDF quote is under 60 seconds.
Above 100 A single-phase (or any 3-phase 480 V branch/feeder), residential-style 1-inch breakers stop being available and molded-case circuit breakers (MCCBs) take over. Each of the four majors sells a family segmented by frame size (physical envelope) and interrupting rating class (H = high, N = normal, S = super-high). Interrupting rating drives everything — a breaker rated 25 kAIC at 480 V will fail catastrophically on a system with 42 kA available fault current. Run a short-circuit study before specifying the frame.
| Brand | Family | Frame sizes (A) | Poles | AIC class @ 480 V | Typical application |
|---|---|---|---|---|---|
| Square D | Powerpact H-frame | 15–150 A | 1P/2P/3P | 25–65 kAIC | Feeder + branch in Powerpact I-Line panelboards |
| Square D | Powerpact J-frame | 150–250 A | 3P | 25–65 kAIC | Feeder in I-Line + NF panelboards |
| Square D | Powerpact L-frame | 250–600 A | 3P | 25–65 kAIC | Feeder / main |
| Square D | Powerpact M-frame | 800–1200 A | 3P | 35–65 kAIC | Service main |
| Eaton | Series C F-frame | 15–150 A | 1P/2P/3P | 25–65 kAIC | PRL panelboards, feeder + branch |
| Eaton | Series C K-frame | 70–400 A | 3P | 25–65 kAIC | Feeder in PRL2a/PRL3a |
| Eaton | Series C L-frame | 300–800 A | 3P | 25–100 kAIC | Feeder / main |
| Eaton | Series C N-frame | 300–1200 A | 3P | 65–100 kAIC | Service main |
| Siemens | Sentron ED | 15–125 A | 1P/2P/3P | 25–65 kAIC | P1/P2 panelboards |
| Siemens | Sentron FD | 70–250 A | 3P | 25–65 kAIC | P4 panelboards, feeder |
| Siemens | Sentron JD | 125–400 A | 3P | 35–65 kAIC | Feeder / main |
| Siemens | Sentron LD/HLD | 300–1200 A | 3P | 35–100 kAIC | Service main |
| GE | Spectra SF | 15–125 A | 1P/2P/3P | 25–65 kAIC | Spectra panelboards |
| GE | Spectra SG/SGH | 70–600 A | 3P | 25–100 kAIC | Feeder + main |
| GE | Spectra SK/SKH | 300–800 A | 3P | 35–100 kAIC | Service main |
| GE | Spectra SL | 400–1200 A | 3P | 35–100 kAIC | Service main |
⚠ AIC labels have to match the sticker — verify with the manufacturer, not the seller.
Grey-market and refurbished commercial MCCBs are a real hazard. A Powerpact H-frame labeled 65 kAIC that was actually manufactured in an unauthorized facility may only clear 25 kA — and on a 42 kA fault, the breaker will not open cleanly. Every PES-shipped commercial MCCB comes with a manufacturer serial and a warranty registration link; if a distributor cannot provide those, do not install the breaker.
Interrupting rating is the maximum fault current a breaker can safely clear at its rated voltage. Undersizing it is the most common cause of catastrophic breaker failure. The available fault current at any point in the system is set by the transformer size (kVA), the transformer impedance (Z%), and the wire size and distance from the transformer. Rule of thumb for a 480 V service:
| Utility transformer (kVA) | Impedance | Available fault at main (kA) | Minimum AIC needed at main | Downstream AIC (100 ft #4/0 feeder) |
|---|---|---|---|---|
| 150 kVA | 3 % | 6.0 kA | 10 kAIC | 10 kAIC |
| 300 kVA | 3.5 % | 10.3 kA | 22 kAIC | 22 kAIC |
| 500 kVA | 4 % | 15.0 kA | 22 kAIC | 22 kAIC |
| 750 kVA | 5 % | 18.0 kA | 25 kAIC | 22 kAIC |
| 1000 kVA | 5 % | 24.0 kA | 35 kAIC | 25 kAIC |
| 1500 kVA | 5.5 % | 32.7 kA | 42 kAIC | 35 kAIC |
| 2000 kVA | 5.75 % | 41.7 kA | 50 kAIC | 42 kAIC |
| 2500 kVA | 5.75 % | 52.2 kA | 65 kAIC | 50 kAIC |
For a rigorous number use the point-to-point short-circuit calculator on the PES contractor portal — enter the utility-provided available fault current at the transformer secondary, the wire size, and the distance to each panel, and the tool returns the fault current at every downstream panel plus the minimum AIC required for every breaker below it. Every commercial job over 200 A needs this study before order.
Two related topics contractors run into: series ratings (using an upstream high-AIC breaker to protect a downstream lower-AIC breaker under UL 489) and SCCR (short-circuit-current rating for industrial control panels under UL 508A). Series ratings save real money on large equipment but only if the specific upstream/downstream combination is UL-listed together — you cannot mix a Square D main with an Eaton downstream and claim a series rating. Every listed combination is published in the manufacturer's series-rating table.
Arc-flash energy (calories per cm²) at every panel is calculated per IEEE 1584-2018 and published on a warning label per NFPA 70E. Faster-clearing breakers (electronic trip units with instantaneous adjustable settings) reduce incident energy dramatically. All four majors sell electronic-trip retrofits: Square D MicroLogic, Eaton Digitrip, Siemens ETU, GE MicroVersaTrip. On new commercial work — anything above 400 A — spec the electronic trip; the arc-flash reduction routinely drops PPE requirements from Category 3 to Category 1.
Confirm the service transformer and available fault current
Ask the utility for the available fault current at the secondary of the serving transformer. For a 1000 kVA 480 V transformer at 5 % Z that's roughly 24 kA. Every breaker at the service and immediately downstream needs to be rated for that fault current or higher.
Size the breaker per NEC 215.3 and 240.4
Feeder overcurrent protection is set to protect the conductor. For a 400 A feeder, standard size is 400 A. Use 250 kcmil Cu THWN-2 (335 A base ampacity × 1.25 for 100 % continuous) or parallel 3/0 Cu (200 A × 2). Verify with NEC 310.16 at your ambient / conduit fill.
Pick the frame — L-frame (Square D / Eaton), JD / LD (Siemens), SG / SK (GE)
For 400 A 3P at 480 V: Square D Powerpact L-frame LDL36400, Eaton Series C LD3400F, Siemens Sentron JXD63B400, GE Spectra SGDA36AT0400. Pick the AIC class that matches or exceeds the calculated fault current — 35 kAIC minimum on this example.
Decide thermal-magnetic vs electronic trip
Thermal-magnetic is cheaper and fine for feeders. Electronic trip (Square D MicroLogic, Eaton Digitrip 310+, Siemens ETU, GE MicroVersaTrip) is required if the arc-flash study needs a faster clearing time to reduce PPE category — very common on service and generator main breakers.
Add ground-fault protection per NEC 230.95 if solidly-grounded >1000 A
Any 480 V wye service ≥ 1000 A solidly grounded needs ground-fault protection (GFP). At 400 A the code does not require GFP, but many owners spec it anyway for equipment protection.
Series rating vs full AIC — check the manufacturer table
If you want a lower-AIC downstream breaker in the feed-through, verify the specific upstream/downstream combination is UL-listed for series in the manufacturer's series-rating table. Mismatched brands cannot claim series rating.
Are Square D QO and Eaton CH breakers interchangeable in a Square D load center?
No. Square D load centers are UL-listed only for QO breakers (and QOB for the bolt-on version). Eaton CH will physically slide in but is not UL-listed for that panel; it voids the panelboard listing and the AHJ will flag it. For a UL-classified interchangeable breaker rated to seat in Square D QO panels, use the Eaton 'CL' classified series specifically — but check the panel label first.
What is the actual difference between Eaton BR and Eaton CH?
BR is a 1-inch value-tier breaker (10 kAIC); CH is a 3/4-inch premium-tier breaker (10 kAIC, 22 kAIC on CHB), tighter dimensional tolerance, and used with Eaton CH load centers. CH gets you more spaces in the same enclosure but at ~1.6× the per-breaker cost. Use CH when the panel needs more circuits than a BR panel can hold; use BR for value builds.
Do you carry Square D QO Plug-on Neutral (PON) load centers and matching breakers?
Yes. Plug-on-neutral eliminates the pigtail on every AFCI / GFCI / DFCI breaker — pin the breaker onto the bus and the neutral connects automatically. Square D QO Plug-on Neutral (QOP) panels are the mainstream 2023-NEC-compliant build; the AFCI/GFCI/DFCI breakers are marked with a '-PN' suffix.
What interrupting rating do I need on a 500 kVA 480 V service?
For a 500 kVA 480 V transformer at 4 % Z, available fault at the secondary is approximately 15 kA. Every breaker at the service main and immediately downstream needs at least 22 kAIC. Wire-length attenuation drops the downstream fault current with distance — run a point-to-point study to size downstream breakers precisely.
How do you handle 100 % rated breakers?
Standard breakers are rated 80 % continuous. A 100 %-rated breaker (available on Powerpact L/M, Series C L/N, Sentron LD, Spectra SG/SK/SL) can carry its full nameplate current continuously and is spec'd on service mains near their rating. The panelboard has to be listed for 100 % operation too — check the label.
Can I install a Homeline breaker in a QO panel to save money?
No. Homeline (HOM) breakers are only listed for Homeline load centers. The bus stab geometry is different and forcing a HOM breaker into a QO panel can create a poor contact that overheats. Kentucky and Ohio inspectors write this up routinely.
What is the arc-flash rating on a Square D Powerpact L-frame with MicroLogic trip?
Interrupting rating and arc-flash rating are different. AIC is 25/35/65/100 kA depending on the L-frame class. Arc-flash incident energy depends on the trip settings and clearing time — the MicroLogic electronic trip with the instantaneous set to minimum typically drops incident energy to under 8 cal/cm² at 18 inches on a 1000 A feeder, moving PPE from Category 3 to Category 2. Every job needs an IEEE 1584 study to publish the actual label.
Registered contractors — free calculators on the axis.pesdistribution.com portal
- Voltage Drop Calculator — NEC 210.19(A) informational note voltage-drop math for branch and feeder circuits, any conductor size.
- Load Balance Calculator — per-phase load balancing and neutral current on 3-phase 4-wire services.
- Conduit Fill Calculator — NEC Chapter 9 Table 1 fill percentages for EMT, RMC, PVC, and FMC in any trade size.
- Short Circuit / AIC Calculator — point-to-point available fault current at every panel and breaker AIC verification.
Register for the PES contractor portal → Free. Verified electrical contractors only.
Order Square D, Eaton, Siemens, and GE breakers at contractor pricing
Authorized-channel inventory — QO/BR/QP/THQL residential and Powerpact/Series C/Sentron/Spectra commercial molded-case. Warranty registers, AIC labels are manufacturer-verified, and same-day will-call from Louisville, KY.
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