Transfer Switch vs Interlock in Fort Myers Homes | CoHarbor Electric

Transfer Switch vs Interlock in Fort Myers Homes

We’ve had this conversation more times than we can count — especially after a storm rolls through and knocks power out around Fort Myers. Homeowners call and ask, “Do I really need a transfer switch for my generator, or can I just use an interlock?”

It’s a fair question. Both systems connect a generator to your home’s electrical panel, and both can keep your lights on when the power goes out. But they’re not the same thing — not even close.

We’ve installed both setups all over Lee County — from newer homes in Gateway to older ranch-style houses near McGregor — and the right choice really depends on your home, your generator, and what you’re trying to power.

Let’s break it down in plain English: what a transfer switch does, what an interlock kit does, and which one makes more sense for Fort Myers homeowners who want safe, reliable backup power.

What an Interlock Kit Is (and Isn’t)

An interlock kit is basically a mechanical safety plate that sits on your electrical panel. It’s designed to keep the main breaker and the generator breaker from being on at the same time.

Here’s how it works:
When the power goes out, you turn off the main breaker, slide the interlock plate, and then turn on the breaker connected to your generator. That feeds power into your home’s circuits through the panel.

It’s a clever, simple solution. And for portable generators — the kind you roll out during outages — it’s a popular option.

Pros:

• It’s affordable — typically $400 to $800 installed.

• You can power almost any circuit in your panel, depending on your generator size.

• It keeps the setup neat — no extra panels or boxes on your wall.

Cons:

• It’s manual — you’ve got to be home to make the switch.

• You can’t use it with a standby (automatic) generator.

• It’s not a “plug-and-play” solution; it requires attention and understanding of your panel.

For smaller homes or anyone using a portable generator under 10,000 watts, an interlock can be a solid choice. But it’s not for everyone — and it’s not foolproof.

What a Transfer Switch Does

A transfer switch is the more advanced option — and the one most homeowners choose when they install a standby generator.

It’s an automatic control system that monitors your home’s power. The second the grid goes down, it cuts your house off from utility power and switches over to generator power — automatically.

No walking out in the rain, no flipping breakers, no risk of backfeeding the grid.

When the power returns, it senses the utility voltage, switches you back, and shuts the generator down. Smooth, safe, and seamless.

Pros:

• Fully automatic (hands-off operation).

• Required for whole-home standby systems.

• Safer for linemen and your equipment.

• Handles large loads (AC units, well pumps, pool systems).

• Cleaner power transition — no “flicker” or surge risk.

Cons:

• Higher cost — typically $1,800 to $3,000 installed.

• Requires proper load calculation and wiring.

• Needs permitting and inspection (which we handle).

A transfer switch isn’t just a fancy add-on — it’s what makes a standby generator automatic.

Safety Differences: The Big One

Here’s where we always get serious with homeowners: both setups can work, but safety comes first.

An interlock relies on you to follow the steps correctly every time. If you forget to shut off the main breaker before starting the generator, you can accidentally backfeed power into the utility grid. That puts lineworkers at risk and can damage your generator when power’s restored.

A transfer switch physically separates the two power sources. There’s no way to cross-connect them. That’s why it’s the only system approved for permanent standby generators.

We’ve seen a few “DIY interlock” setups go bad because someone skipped a step or used undersized wire. Not worth the risk when you’re talking about 240 volts at high amperage.

Code and Permitting in Fort Myers

Both systems need to meet the National Electrical Code (NEC), and Lee County inspectors enforce those standards strictly — especially after hurricane season, when everyone’s rushing to install generators.

• Interlock kits must be UL-listed for your exact panel model. Generic kits won’t pass inspection.

• Transfer switches must be installed by a licensed contractor (like us) and tied to a proper generator circuit.

We pull permits for both systems, handle the load calculations, and make sure every installation is up to Fort Myers standards — so when the inspector shows up, it’s an easy sign-off.

Real Job Example: Upgrading from Interlock to Transfer Switch

A homeowner off McGregor called us last year after Hurricane Idalia. They had a portable generator with an interlock setup we’d installed for them a few years earlier. It had worked fine, but they decided they were done rolling that heavy generator out every storm.

They upgraded to a 22kW whole-home Generac standby system, which meant it was time to move from interlock to transfer switch.

We installed a 200-amp automatic transfer switch, mounted cleanly beside the main panel, and ran new conduit to the generator pad out back. We tied it into their propane tank and tested the full load.

When the next outage hit a few months later, they didn’t have to do a thing — the power went out, the generator kicked on in about 10 seconds, and the house kept humming along like nothing happened.

The homeowner told us later, “I wish we’d done this years ago.”

Which System Is Right for You?

Here’s the honest breakdown:

If you want a simple, affordable way to power the basics during short outages — lights, fridge, fans — an interlock can get the job done.

If you want full-home, seamless, storm-proof power, a transfer switch paired with a standby generator is worth every penny.

What We Tell Fort Myers Homeowners

Both systems have their place, but if you live in Fort Myers — where storms can knock out power for days — you’ll appreciate the peace of mind that comes with automation.

We’ve seen interlocks work great for weekend cabins and smaller homes, but in Florida’s hurricane zones, most families prefer the reliability of a transfer switch.

We handle both types of installs, and we’re happy to talk you through which one fits your needs and your home’s layout best.

Wrapping It Up

Backup power isn’t a luxury anymore in Fort Myers — it’s a necessity. Whether you’re looking for a basic interlock setup for your portable generator or a full automatic standby system with a transfer switch, the key is doing it right.

Safe wiring, proper grounding, and code compliance aren’t optional — they’re what make sure your system works when you need it most.

👉 Call Coharbor Electric today to schedule a generator connection consultation. We’ll inspect your panel, explain your options clearly, and install the right setup — clean, safe, and ready for hurricane season.

We make backup power simple, reliable, and built for Florida’s toughest storms.