Best Interlock Kit for Generator: Safe, Easy Backfeeder Solutions
The best interlock kit for a generator safely directs power from a portable unit to your home’s circuits, preventing backfeed and protecting both your generator and grid power. This guide highlights five top options ideal for common Square D QO/Homeline, Eaton/Cutler Hammer BR, and Siemens/Murray panels. Each pick targets different panel compatibility and spacing needs, helping you choose the right kit for your setup. These kits are best for homeowners seeking reliable backfeed safety, straightforward installation, and compatibility with standard 150–200 amp panels.
Top picks at a glance:
| Product | Brand | Panel Compatibility | Spacing | Best For |
|---|---|---|---|---|
| Natupal Interlock Kit (SD200A) | Natupal | Square D QO/Homeline 150/200 A | 1 3/8 in | Premium Square D compatibility, solid build |
| QYZZRS Interlock Kit | QYZZRS | Square D QO/Homeline 150/200 A | 1 3/8 in | Easy alignment guidance and clear notes |
| EXCELFU Interlock Kit for BR/CH | EXCELFU | Eaton Cutler Hammer BR/CH 150/200 A | 1 1/4–1 7/16 in | Safe backfeed for BR/CH series |
| XMK Interlock Kit for Siemens/Murray | XMK | Siemens/Murray 150/200 A | 7/8–1 1/4 in | Budget-friendly Siemens/Murray option |
| SPZOCE Interlock Kit for BR/Siemens/Murray | SPZOCE | Siemens/Murray 150/200 A | 1 1/4–1 7/16 in | Common spacing range, robust install kit |
Natupal Generator Interlock Kit for Square D QO or Homeline
Compatible Models: Square D QO or Homeline 150/200 amp panels. Spacing: 1 3/8 inches between the main and generator breaker. This safety interlock directs generator power to home circuits while preventing power from feeding back to the grid. Best for homes with Square D panels seeking a straightforward, factory-aligned interlock.
Who it’s best for: Homeowners with QO or Homeline panels who want a professionally aligned kit and clear installation steps. Why selected: Proven compatibility with popular Square D panels and a documented spacer requirement. Caution: Verify exact panel model and slot layout before installation to ensure correct alignment.
QYZZRS Interlock Kit for Square D QO/Homeline
Compatible Models: Square D QO and Homeline panels, 150/200 amp. Spacing: 1 3/8 inches between main and generator breaker. Notes emphasize proper initial screw placement and alignment to reduce installation errors. This kit is a solid choice for those who want a clear setup process with Square D systems.
Who it’s best for: Do-it-yourselfers who prefer explicit pre-installation steps. Why selected: Tight coupling with QO/Homeline layouts and explicit guidance for alignment. Caution: Follow the installation note precisely to avoid alignment mistakes that could affect operation.
SPZOCE Interlock Kit for Eaton Cutler Hammer BR/CH
Compatible Models: Eaton/Cutler Hammer BR/CH 150/200 amp panels. Spacing: 1 1/4–1 7/16 inches between main and branch breakers. Easy installation is supported by included drill bit and detailed manual. Safety: Directs generator power to circuits safely, reducing backfeed risk.
Who it’s best for: Homes using Eaton BR/CH panels seeking a robust installation and compatibility with plug-in neutral variants. Why selected: Clear spacing range and a focus on safe generator backing. Caution: Confirm the panel model matches BR or CH and that neutrals are compatible with your panel variant.
SPZOCE Square D/Interlock for QO/HomeLine (SD) 150/200 A
Compatible Models: Square D QO or Homeline 150/200 amp panels. Spacing: 1 3/8 inches between main and generator breakers. Easy installation features and a detailed manual. Safety: Prevents simultaneous mains and generator power, ensuring reliable operation of household circuits during outages.
Who it’s best for: Square D users who want a familiar mounting footprint and explicit spacing guidance. Why selected: Similar to other SD-ready options with a focus on safety and compatibility. Caution: Ensure the SD200A variant matches your panel’s exact model number and slot arrangement.
Generator Interlock Kit for Eaton BR 100/125 A
Compatible Models: Eaton/ Cutler Hammer BR 100/125 amp panels. Spacing: 1 1/4–1 7/16 inches between main and branch breakers. This interlock enables safe backfeeding for smaller BR panels and adjacent main/branch setup. Safety: Keeps home circuits usable during outages while avoiding backfeed hazards.
Who it’s best for: Homes with BR 100/125 A panels seeking a compact, cost-conscious option. Why selected: Covers smaller BR panels where space is tighter. Caution: Not ideal for 150/200 A BR panels where larger spacings are standard; confirm your panel rating before purchase.
Buying Guide
What panel type do you own?
Interlock kits are panel-specific. Square D QO/Homeline, Eaton BR/CH, Siemens/Murray, and similar families require corresponding interlock designs. Confirm your panel model and amperage (150/200 A) before choosing.
What spacing do you need?
Most kits list spacing between main and generator breakers. Common ranges include 1 3/8 inches, and between 7/8 and 1 1/4 inches. Match the spacing to your panel’s available breaker slots to ensure a secure fit.
Installation considerations
Look for kits that include installation hardware (drill bit, screws) and clear manuals. An easy-install kit reduces the risk of misalignment. If you’re not confident with panel work, consider professional installation.
Safety and backfeed awareness
Interlock kits prevent simultaneous connection of mains and generator power. They help ensure generator power feeds only designated circuits and never backfeeds into the grid. Always power down and follow safety procedures when installing or operating with a generator.
Compatibility versus price
Higher compatibility with your panel can offer a simpler install and better reliability. If two kits fit your panel, compare installation guides, included hardware, and the spacing to choose the more straightforward option, rather than selecting solely on price.
Summary and practical tips
For Square D QO/Homeline, Natupal and QYZZRS provide strong alignment with standard 1 3/8 in spacing. For Eaton BR/CH panels, EXCELFU and SPZOCE offer solid options with precise spacing ranges. For Siemens/Murray, XMK and SPZOCE cover common 150/200 A setups. Verify exact model numbers, panel type, and spacing before purchase to ensure a safe, compliant install.
FAQ
- What is an interlock kit for a generator?
An interlock kit is a device that allows you to backfeed a generator into selected circuits while ensuring the main power and generator power cannot feed each other at the same time.
- Do I need a separate transfer switch if I use an interlock kit?
No. An interlock kit replaces the need for a manual transfer switch by preventing backfeed and coordinating breaker positions. Some setups may still use a transfer switch for multiple circuits; consult a professional for your panel.
- Can I install an interlock kit myself?
Installation is possible for those comfortable with breaker panels. Follow the manufacturer’s manual closely and power down the service before starting. If unsure, hire a licensed electrician.
- Will an interlock kit work with any panel?
Interlock kits are panel-specific. Ensure the kit is listed for your exact panel brand, series, and amperage (e.g., 150/200 A).
- What spacing should I expect for my kit?
Spacing typically ranges from 7/8 inch to 1 3/8 inches, depending on the model and panel. Verify the measurement against your panel’s breaker arrangement.
- Are there safety cautions I should consider?
Yes. Backfeeding can be dangerous to utilities and equipment if misused. Always follow manufacturer instructions, never backfeed when the main breaker is on, and ensure the generator is properly grounded.