Best Interlock Device for Electrical Panels: Safe Generator Backfeed Solutions
In homes and small businesses, an interlock device is a crucial safety tool that prevents backfeeding when a portable generator is in use. This guide highlights five top interlock kits compatible with popular panel brands, explaining what to look for and how each kit supports safe, reliable power during outages. Each product section includes a direct link to the Amazon listing and a quick visual reference.
Overview Of Selected Interlock Kits
| Product | Brand | Panel Type | Spacing (Main to Generator) | Key Benefit |
|---|---|---|---|---|
| Generator Interlock Kit GE 150/200 Amp | EXCELFU | GE 150/200 Amp | 1 1/4″ | Safe transfer of power with no double supply |
| Generator Interlock Kit Eaton BR 150/200 | EXCELFU | Eaton/Cutler Hammer BR | 1 1/4″ – 1 7/16″ | Backfeeds safely to home circuits during outages |
| GE Vertical Main 150/200 Amp Interlock | QYZZRS | GE Vertical Main | 2 1/2″ – 3 1/2″ | Rigid spacing for safe switching |
| Square D QO/HomeLine 100/125 Amp Interlock | XMK | Square D QO/Homeline | 3/4″ – 7/8″ | Compact, reliable generator backfeed |
| Siemens/Murray 100 Amp Interlock | XMK | Siemens/Murray 100 | 7/8″ – 1 1/4″ | Flexible spacing for various panel configurations |
Note: This selection focuses on compatibility with common American panel brands and emphasizes safe, code-compliant backfeeding to support essential appliances during outages.
GE Interlock Kit For 150/200 Amp Panels
Brand: EXCELFU. Compatible with General Electric GE 150 or 200 Amp panels. The kit provides 1 1/4 inches spacing between the main breaker and branch breakers. It prevents both mains and generator power from feeding the panel simultaneously, directing generator power safely to selected circuits during outages. This ensures household appliances remain powered without risking backfeed to utility lines.
Eaton/Cutler Hammer BR Series Interlock Kit
Brand: EXCELFU. Designed for Eaton/Cutler Hammer BR Series panels (and CH series with plug-in neutral). Offers 1 1/4″ to 1 7/16″ spacing between main and branch breakers. The kit enables safe backfeeding from a portable generator and prevents simultaneous mains and generator supply, helping keep home circuits powered during outages safely and cost-effectively.
GE Vertical Main Interlock Kit (150/200 Amp)
Brand: QYZZRS. Spacing ranges from 2 1/2″ to 3 1/2″ between main and branch breakers. This professional interlock kit supports safe generator backfeed for GE vertical main panels, with emphasis on preventing concurrent energization of utility and generator sources during outages.
Square D QO/Homeline Interlock Kit (100/125 Amp)
Brand: XMK. Compatible with Square D QO or Homeline 100 and 125 Amp panels. Provides a 3/4″ to 7/8″ spacing between the main and branch breakers. Designed for safe, cost-effective backfeeding from a portable generator to essential home circuits during outages.
Siemens/Murray 100 Amp Interlock Kit
Brand: XMK. Compatible with Siemens/Murray 100 Amp panels. Offers flexible spacing options around 7/8″ to 1 1/4″ depending on panel configuration. Ensures safe generator backfeeding by mechanically interlocking the main breaker with the generator breaker, preventing simultaneous energization from both sources.
Buying Guide: Key Considerations For Interlock Kits
When choosing an interlock kit, consider panel compatibility, spacing requirements, and installation complexity. Confirm the kit matches your panel brand and model (GE, Eaton/Cutler Hammer, Siemens/Murray, Square D QO/Homeline, etc.). Measure the spacing needed between main and generator breakers to ensure proper fit. Look for corrosion-resistant materials, sturdy construction, and clear installation instructions or templates. Safety features such as mechanical interlocking to prevent backfeed, lockout capabilities, and regulatory compliance improve reliability during outages. Some kits require professional installation—factor this into overall cost and downtime. Compare kits based on the maximum amperage supported, ease of retrofitting, and whether plug-in neutrals are accommodated, as these affect compatibility with existing electrical systems.
From a reliability perspective, choose a kit with robust mounting hardware, a proven track record in preventing backfeed, and a straightforward testing procedure to verify correct alignment before use. For homeowners prioritizing convenience, look for compact designs with universal mounting options and precise spacing specs. For electricians or installers, evaluate ease of wiring, the availability of drilling templates, and whether the kit supports both indoor and outdoor installations. Finally, verify warranty terms and ensure the product adheres to local electrical codes and standards.