Best Generator Interlock Device Kits for Safe Backfeeding in 2026
Answering the question, these interlock devices are designed to safely backfeed a generator into a home electrical panel, preventing simultaneous mains and generator power. They’re best for homeowners who want a code-compliant, reliable backup power solution during outages. The top picks below cover Siemens/Murray, Square D, Eaton/Cutler Hammer, GE, and Square D vertical main configurations. A quick summary table is provided to compare key details at a glance.
| Product | Panel Type | Spacing | Best For | Notes |
|---|---|---|---|---|
| Generator Interlock Kit Compatible with Siemens or Murray | Siemens/Murray 150-200A | 7/8″ – 1 1/4″ | Siemens/Murray users seeking a compact interlock | Includes 7/8″ to 1 1/4″ spacing; safety guaranteed |
| QYZZRS Interlock Kit for Square D QO/Homeline | Square D QO/Homeline 150-200A | 1 3/8″ | Square D panels needing precise spacing | Professional kit; installation guidance included |
Generator Interlock Kit Compatible with Siemens or Murray
Best for Siemens and Murray panels, this interlock kit ensures a 7/8″ to 1 1/4″ spacing between main and branch breakers. It prevents simultaneous mains and generator power, while directing generator energy to home circuits safely. Choose this if you have a Siemens or Murray panel and need a reliable, straightforward installation path. Limitation: verify model compatibility and spacing before purchase to avoid mismatches.
QYZZRS Interlock Kit for Square D QO or Homeline
Best for Square D QO/Homeline 150-200A panels, this interlock kit requires 1 3/8″ spacing between the main and generator breaker. It’s a solid choice when aligning components is critical during installation. Best for rebuilding or upgrading an existing Square D setup. Caution: follow the included screws and alignment test instructions to avoid misalignment.
Natupal Interlock Kit for Square D QO or Homeline
Best for Square D QO/Homeline 150-200A panels needing 1 3/8″ spacing, this professional interlock kit provides a robust, clear installation path. It aims to minimize outages by ensuring safe generator power distribution. Consider this if you’re upgrading older interlock hardware; inspect the spacing and alignment notes prior to installation.
QYZZRS Interlock Kit For Eaton Cutler Hammer
Best for Eaton Cutler Hammer 100-125A panels, this professional interlock kit supports safe backfeeding of a generator. It includes detailed installation notes and a complete hardware set for straightforward mounting. Better for users with 100A or 125A Eaton panels who need a compact, reliable interlock solution. Limitation: confirm that the kit matches your exact breaker arrangement and neutral requirements.
EXCELFU Interlock Kit for Eaton BR Series
Best for Eaton BR series 150-200A panels, this horizontal interlock kit uses a 1 1/4″ to 1 1/16″ spacing between the main and branch breakers. It’s a practical option for households seeking a cost-effective backfeed solution with proven horizontal mounting. Choose this if your BR panel mirrors the stated spacing; avoid if your panel uses a different neutral configuration.
EXCELFU Interlock Kit for GE 150/200A Panels
Best for General Electric GE 150-200A panels, this interlock kit features a 1 1/4″ spacing between main and branch breakers. It aims to safely direct generator power to selected circuits while preserving appliance operation during outages. Use this when GE panels match the 1 1/4″ spacing requirement; caution: verify compatibility with your GE model before purchasing.
XMK Interlock Kit for Siemens/Murray 100A
Best for Siemens/Murray 100A panels with plug-on neutral configurations, this kit provides a 7/8″ to 1 1/4″ spacing between main and branch breakers. It’s suitable for small-to-mid sized home systems and emphasizes safe, exclusive power routing to keep essential circuits alive during outages. Limitation: ensure correct spacing type for plug-on-neutral vs non plug-on-neutral panels.
Buying Guide
What should I check before buying an interlock kit?
Panel compatibility is the most important factor. Verify the panel brand, model, and amperage (100A, 150A, 200A) and the exact spacing required between main and generator or branch breakers. Some kits are designed specifically for plug-on neutral panels; others are for non plug-on neutral configurations. Ensure the kit includes the necessary mounting hardware and installation instructions for your panel model.
How does spacing affect installation?
Spacing determines whether the interlock plate will physically align with the breakers. Incorrect spacing can cause improper engagement or unsafe backfeeding. Common spacings include 7/8″ to 1 1/4″ and 1 3/8″ to 1 7/16″ for various panel lines. Choose a kit whose spacing matches your panel’s main-to-generator breaker layout.
Which kit is easiest to install?
Kits that provide complete hardware, clear installation bulletins, and test procedures tend to be easier. Look for packages that include screws, drill bits, labels, and step-by-step alignment guidance. Some products also emphasize pre-installation alignment checks to reduce errors during mounting.
Safety and compliance considerations
Interlock devices are designed to prevent backfeeding that could endanger utility workers or appliances. Ensure the kit is appropriate for your panel’s configuration and that installation follows local electrical codes. If in doubt, consult a licensed electrician to verify compatibility and perform the install.
Usage scenarios
Best candidates include homes in outage-prone areas, homes with critical loads, and users seeking a reliable generator backfeed that does not require manual switching at the main panel. Consider whether you need simple operation or advanced labeling and testing protocols to facilitate regular safe use.
FAQ
- What is a generator interlock kit? A device that prevents simultaneous connection of mains and generator power and directs generator power to selected circuits safely.
- Do I need a licensed electrician to install one? Installation can be DIY, but local codes may require professional installation for compliance and safety.
- Will this work with my exact panel model? Check the panel brand, amperage, and spacing requirements; match the kit’s specifications precisely.
- What spacing should I look for? Spacing options vary by panel line (common options include 7/8″ to 1 1/4″ and 1 3/8″).
- Can I use multiple interlock kits? Most setups use a single interlock per panel to control generator backfeed; verify with kit instructions.
- Is backfeeding dangerous? When installed correctly, interlock kits provide a safer alternative to backfeeding through outlets, reducing risk to personnel and appliances.