How to Wire Back Up Generator to Home | The Safe Hookup

Wire a back up generator to your home only through approved transfer equipment, never by plugging it into a wall outlet.

One wrong connection can send electricity back through the utility lines and kill a lineman blocks away. The safe way to hook a portable generator into your home’s wiring is a transfer switch or an interlock-equipped panel, installed by a qualified electrician and fed through an outdoor inlet box. Skip the extension-cord chaos and the dangerous “dryer outlet” tricks — here is the setup that meets US electrical code and actually protects your family.

Why a Generator Can’t Just Plug Into a Wall Outlet

Backfeed is the killer. When you connect a generator directly to a wall outlet or breaker, power flows backward through your panel, out the utility meter, and onto the grid. Utility workers repairing lines expect them dead; your generator can electrocute them. It can also overload your wiring and start a fire when the grid comes back.

That is why the National Electrical Code requires transfer equipment for fixed or portable optional standby systems. The only exceptions involve written safety procedures and physical isolation of the normal supply — not something a homeowner does by flipping a breaker.

The Safe Wiring Setup, Step by Step

Every code-compliant residential setup follows the same path: generator → outdoor inlet box → transfer switch or interlock → your home’s circuits. Here is how the pieces fit together.

1. Set the generator up outside, at least 10 feet from the house. Generators produce carbon monoxide, and placement against a wall or under a window can be deadly.

2. Have an electrician install the inlet box and transfer equipment.

This is not a DIY afternoon. The inlet box mounts on an exterior wall, and the transfer switch or interlock goes in or beside your main panel. The electrician also handles the grounding and bonding details that vary with your setup — specifically whether the generator is a separately derived or nonseparately derived system — because getting that wrong can create a shock hazard even when the wiring looks right.

3. Run a generator cord between the generator and inlet box. The cord must match the receptacle on your generator and the inlet on the house. The whole point of the inlet box is that the generator cord connects there — never into a dryer outlet or wall socket.

4. Start the generator, then switch over. With a manual transfer switch or interlock, you first switch off the utility main so the grid is isolated, then energize the circuits you want powered. An automatic transfer switch, by contrast, monitors both utility and generator voltage and shifts your loads to the generator on its own when the power drops.

5. When utility power returns, reverse the process. Shut down the generator, return the transfer equipment to utility power, then bring your circuits back one by one.

Transfer Switch vs. Interlock: What’s Allowed Where

Both are legitimate, but they are not the same device, and local rules differ.

But codes and utility rules vary by jurisdiction, and some local inspectors require a listed transfer switch while others accept an interlock. Check with your local building department before you commit to either.

Common Mistakes That Endanger Homes and Crews

The worst errors are the ones that look convenient. Plugging a generator into a dryer outlet or wall outlet is the classic backfeed hazard. Failing to isolate the utility supply puts linemen at risk even when the generator runs fine. Skipping the grounding and bonding check can leave your own panel at a dangerous potential. And running the generator indoors or too close to the house turns a power outage into a carbon monoxide emergency.

If you are comparing generators before you plan the hookup, our tested picks for home backup generators cover the models worth the money. Whichever unit you choose, budget for the transfer equipment and the electrician’s labor — the wiring is what makes it safe.