A generator interlock kit is the safe, affordable way to power your home’s circuits from a portable generator, mechanically preventing the dangerous condition of backfeeding the grid while the utility power is out. It is a fraction of the cost of a transfer switch and works with your existing breaker panel. The key is matching the kit to your exact panel brand and amperage. This guide compares the best interlock kits available now.
We compared the generator interlock kits homeowners rate most highly, weighing panel compatibility, build, and value. Here are five picks and the panel each one suits.
Safety note: interlock installation involves your main electrical panel and should be done by, or with, a licensed electrician and to local code.
Prime Generator Interlock Kit for Eaton Cutler Hammer 100A and 125A BR Series Panels,Interlock Kit for Eaton Cutler Hammer 100 Amp and 125 Amp for BR Series Panels with Adjacent Main and Branch Breakers
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Quick Comparison
| Interlock Kit | Rating | Reviews | Best For |
|---|---|---|---|
| Square D QO/Homeline 150-200A | 4.7/5 | 1,730+ | Square D large panels |
| Eaton Cutler Hammer BR 100-125A | 4.6/5 | 102+ | Eaton BR panels |
| Square D QO/Homeline 100-125A | 4.5/5 | 84+ | Smaller Square D panels |
| Joinfworld Square D/Homeline | 4.7/5 | 57+ | Budget Square D fit |
| Cutler Hammer/Eaton 100A | 4.4/5 | 50+ | Eaton 100A panels |
Top Picks Reviewed
Square D QO/Homeline 150-200A
The most-reviewed interlock kit, this option fits Square D QO and Homeline 150 or 200-amp panels, the most common in many homes. Its strong rating and broad fit make it the go-to for Square D owners.
Pros:
- Fits common Square D 150-200A panels
- Most-reviewed, trusted
- Inexpensive vs. transfer switch
Cons:
- Must match your exact panel
Best for: Square D 150-200A panels.
Eaton Cutler Hammer BR 100-125A
Designed for Eaton Cutler Hammer 100A and 125A BR-series panels, this kit brings safe interlock switching to those panels. It is the Eaton BR owner’s pick.
Pros:
- For Eaton BR 100-125A panels
- Affordable
- Prevents backfeed
Cons:
- Panel-specific
Best for: Eaton BR-series panels.
Square D QO/Homeline 100-125A
The smaller-panel version fits Square D QO and Homeline 100 or 125-amp panels, covering more compact services. It is the smaller Square D pick.
Pros:
- For 100-125A Square D panels
- Simple mechanical interlock
- Low cost
Cons:
- Amperage-specific
Best for: smaller Square D panels.
Joinfworld Square D/Homeline
A budget interlock kit for Square D QO and Homeline panels, the Joinfworld covers the basics at the lowest price with a strong rating. It is the value Square D pick.
Pros:
- Lowest price
- Strong rating
- Square D/Homeline fit
Cons:
- Confirm exact panel match
Best for: budget Square D installs.
Cutler Hammer/Eaton 100A
An interlock kit for Cutler Hammer and Eaton 100-amp panels, this option serves those specific services safely. It is the Eaton 100A pick.
Pros:
- For Eaton/Cutler Hammer 100A
- Prevents dangerous backfeed
- Cost-effective
Cons:
- Fewer reviews
Best for: Eaton 100A panels.
How to Choose
- Panel brand and model: interlock kits are specific to your panel brand (Square D, Eaton) and breaker series.
- Amperage: match the kit to your panel’s main breaker rating (100A, 125A, 150A, 200A).
- Breaker layout: confirm the kit fits your panel’s specific breaker positions.
- Code compliance: use a kit listed for your panel and follow local electrical code.
- Professional install: have a licensed electrician install or verify it for safety.
Frequently Asked Questions
What is a generator interlock kit?
It is a mechanical slide plate that prevents the main breaker and generator breaker from being on at the same time, safely allowing a portable generator to power home circuits without backfeeding the grid.
How do I choose the right interlock kit?
Match it exactly to your panel brand, breaker series, and amperage. A Square D QO kit will not fit an Eaton BR panel, for example.
Is an interlock kit safe?
Yes, when correctly matched and installed, it is a code-recognized method. Because it involves your main panel, installation should be done by or with a licensed electrician.
Interlock kit or transfer switch?
An interlock kit is cheaper and lets you power any circuit, but requires manual breaker management. A transfer switch is pricier but more automatic for selected circuits.
Our Verdict
Top Pick: the Square D QO/Homeline 150-200A, the most-reviewed kit for common Square D panels. Best Value: the Joinfworld Square D for the lowest price. Premium Pick: the Eaton Cutler Hammer BR for Eaton panel owners.
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