Generator Interlock Kit for Square D QO Panels
Square D makes three QO generator interlock kits, and the one that fits depends on your load center's series number and whether it has a QOM1 or QOM2 main. If your QO series isn't on Schneider's list, or the panel has 60 spaces, there's no Square D kit for it.
Find the kit for your panel
Check the QO label
QO is Square D's premium residential line, and its breakers say QO on the handle. Inside the panel door, look for:
- The series code. Schneider says the correct kit depends on it.
- Indoor (NEMA Type 1) or outdoor (NEMA Type 3R).
- The main breaker frame, QOM1 or QOM2, and its amp rating.
- The number of spaces. No 60-space QO load center has a kit.
The kits are for single-phase, convertible QO main breaker load centers.
The three QO kits
| Kit | Series and enclosure | Main breaker | Generator breaker |
|---|---|---|---|
| QOCRBGK1C | Series G and S indoor; Series G, S1, S2 and S6 outdoor | QOM1, 100 to 125 A | Two-pole QO, 15 to 125 A, no bigger than the main |
| QOCGK2C | Series G and S indoor; Series G and S1 outdoor | QOM2, 150 to 225 A | Two-pole QO, 15 to 125 A |
| QORBGK2C | Series S2 and S6 outdoor | QOM2, 150 to 225 A | Two-pole QO, 15 to 125 A |
Every kit comes with a retaining kit for the back-fed breaker. The QOCGK2C doesn't apply to the QO160M200P or QO160M200PC. Check the full catalog number on your label, not just the first few characters.
How the QO interlock works
The bracket ties the utility main to a back-fed two-pole breaker that serves as the generator main, rated up to 125 A. A sliding arm moves between the two handles, so only one of them can be on. Switching over is quick: main off, slide the arm, generator breaker on, then turn on the circuits you need.
Main lug QO panels
A main lug panel has no main breaker to interlock against. Schneider says certain main lug QO units can be converted to main breaker units and then take a kit:
- Series G and S main lug units, with a QOM1 main, for the QOCRBGK1C.
- Series S main lug units, with a QOM2 main, for the QOCGK2C.
- Series S2 and S6 main lug units, with a QOM2 main, for the QORBGK2C.
The conversion changes how the service is protected, so leave it to the electrician.
If there's no kit for your panel
Older QO series and 60-space panels need another route. A manual transfer switch works with any panel. Some aftermarket interlocks are listed for panels Square D doesn't cover; Interlock Technologies says its kits are MET listed to UL standards. Make sure the listing names your panel before you buy, because inspectors check.
What else you'll need
The kit is just the lockout. Add the two-pole QO back-fed breaker, an outdoor inlet box and a cord rated for your generator's outlet. Interlock Technologies pairs a 30 amp back-feed breaker with generators up to 8,000 watts and a 50 amp setup with bigger ones. QO breakers only go in QO panels, so don't let anyone sell you a Homeline breaker for this.
Sources
- Schneider ElectricWhat are the generator interlock kits available for QO load centers? (opens in a new tab)
- Schneider ElectricHow does the QO / Homeline generator interlock kit work? (opens in a new tab)
- Interlock TechnologiesInterlock kit FAQs (opens in a new tab)