Every year, utility linemen are killed or seriously injured by backfed generators. The scenario is always the same: a homeowner or farmer loses power, plugs a generator into a wall outlet or dryer receptacle with a double-male cord (called a suicide cord for good reason), and starts generating electricity. The generator powers the house through the outlet, but it also sends voltage backward through the main breaker, out the meter, up the service drop, through the transformer, and onto the distribution line at 7,200 to 14,400 volts. A lineman working on that line, believing it is de-energized because the utility switched it off at the substation, touches the wire and is electrocuted.
This is not a theoretical risk. It happens every storm season. Backfeeding is illegal in every jurisdiction, violates the National Electrical Code, and is a felony in some states because it constitutes reckless endangerment. But people still do it because they do not understand the physics, because a transfer switch costs money, and because a double-male cord costs $10 at the hardware store. This guide explains exactly how backfeeding works, why it kills, and what the legal and safe alternatives are.
How a Generator Backfeeds the Grid
Your electrical service works like a one-way street under normal conditions. Utility power flows from the substation, through the distribution lines, through the transformer on the pole, down the service drop to your meter, through the main breaker, and into your panel. Every circuit in your house branches off from the panel. The flow is always from the grid to the load.
When you plug a generator into a wall outlet using a double-male cord, you reverse that flow. The generator pushes voltage into the outlet, which feeds back through the branch circuit breaker into the panel. From the panel, the voltage reaches the main breaker. If the main breaker is closed (which it almost always is, because most people do not think to open it), the generator voltage passes through the main breaker, out to the meter, and up the service drop to the transformer.
The transformer is the critical piece. Your service transformer steps down 7,200 volts (or higher) to 240/120 volts for your house. But transformers work in both directions. A generator pushing 240 volts into the low side of the transformer produces 7,200 volts on the high side. That 7,200 volts is now on the distribution line. It does not matter that the utility disconnected the line at the substation. The generator is energizing the line from the other end.
A lineman working on that line assumes it is dead because the utility opened the disconnect at the substation. He may test the line at the substation end and confirm it is de-energized there. But the backfed voltage is coming from the other direction, from your generator through your transformer. If he does not test at his work location (and the backfed voltage may be intermittent, making testing unreliable), he contacts a line carrying 7,200 volts or more. At that voltage, the current flows through his body and the result is almost always fatal.
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Check if your generator setup is safe from backfeed risk. This decision-tree tool evaluates your transfer switch, connection method, and safety equipment against NEC Article 702 requirements and flags dangerous configurations.
The Suicide Cord: Why It Has That Name
A double-male cord (also called a suicide cord, cheater cord, or backfeed cord) has male plugs on both ends. One end plugs into the generator's outlet. The other end plugs into a wall outlet or dryer receptacle. When the generator is running, one end of the cord has exposed live prongs. If the cord is unplugged from the wall while the generator is running, or if it is plugged into the generator before the wall, the exposed prongs carry 120 or 240 volts. Touching them causes electrocution.
The cord itself is also a fire hazard. Most wall outlets are wired with 14 or 12 gauge wire on 15 or 20 amp breakers. A generator pushing 30 or 40 amps through a 15-amp outlet overloads the wiring in the wall. The breaker should trip, but if the breaker is the one connecting to the generator (and many people use the breaker as a switch), it is intentionally left on or oversized. The 14-gauge wire in the wall heats up, the insulation softens, and a fire starts inside the wall where you cannot see it.
Another risk is the lack of overload protection in the backfeed direction. Circuit breakers protect against current flowing in the normal direction. When current flows backward through the panel, the breaker still provides overcurrent protection, but the coordination between generator output and breaker ratings is uncontrolled. A 5,000-watt generator can push 42 amps at 120 volts through a single 15-amp branch circuit if all other breakers are off and the load is on that one circuit. The branch wiring sees nearly three times its rated current.
Double-male cords are illegal to sell in many jurisdictions, but they are still widely available online and in hardware stores. Some stores sell them labeled "for generator use" with no warning about the lethal risks. Owning or using one in a backfeed configuration violates the NEC, voids your homeowner's insurance, and creates criminal liability if someone is injured or killed. There is no legitimate use for a double-male cord. Period.
Transfer Switches: The Legal and Safe Solution
A transfer switch is a device that physically disconnects your house from the utility grid before connecting it to the generator. It makes backfeeding impossible because the generator and the utility cannot be connected to the panel at the same time. There are two types: manual and automatic.
A manual transfer switch is a panel with 6 to 10 circuit positions that you select as your priority circuits (furnace, refrigerator, well pump, lights). It installs next to your main panel and connects to a generator inlet box on the outside of the house. When power goes out, you plug the generator into the inlet box, start the generator, and flip the transfer switch handle from "Line" to "Generator." This physically opens the utility connection and closes the generator connection. There is no position where both are connected simultaneously. Manual transfer switches cost $200 to $400 for the switch plus $300 to $600 for professional installation. Total: $500 to $1,000.
An automatic transfer switch (ATS) monitors utility power continuously. When it detects an outage, it starts the generator automatically, waits for the generator to stabilize, and then switches the load from utility to generator. When utility power returns, the ATS switches back and shuts down the generator. An ATS is more expensive ($500 to $2,000 for the switch, plus installation), but it provides automatic backup without requiring anyone to be home to start the generator and flip the switch.
For a shop or outbuilding, a simpler option is an interlock kit. An interlock is a mechanical device that mounts on the main panel and physically prevents the main breaker and the generator breaker from being on at the same time. When you slide the interlock to the generator position, it forces the main breaker off, disconnecting from the grid. Interlock kits cost $50 to $150 and can be installed by an electrician in about an hour. They are code-compliant in most jurisdictions and are the least expensive way to safely connect a generator to an existing panel.
Legal Consequences of Backfeeding
Backfeeding without a transfer switch violates Article 702 of the National Electrical Code, which requires a transfer switch for all legally connected standby power systems. It also violates your utility's interconnection rules, which prohibit customer-owned generation from energizing the distribution system without an approved interconnection agreement and protective relaying.
If a backfed generator injures or kills a utility worker, the generator owner faces both criminal and civil liability. Criminal charges can include involuntary manslaughter, reckless endangerment, or negligent homicide depending on the jurisdiction. Civil liability for wrongful death of a utility worker can run into millions of dollars. Homeowner's insurance policies universally exclude coverage for injuries caused by illegal electrical connections, meaning the liability falls entirely on the homeowner.
Even without an injury, backfeeding can result in fines from the utility, disconnection of service, and code violation penalties from the local building department. Some utilities actively look for backfed generators during outages by checking for energized lines in areas that should be de-energized. When they find one, they disconnect the service, and restoring it requires a full electrical inspection and code compliance, which may mean upgrading the entire service panel.
Insurance implications extend beyond liability. If a fire caused by a backfed generator destroys your home or shop, the insurance company can deny the claim based on the illegal electrical connection. You are not only uninsured for the fire damage, but you are also liable for any damage to neighboring properties. The $500 to $1,000 cost of a transfer switch or interlock kit is insignificant compared to the financial exposure of backfeeding.
Sizing and Connecting a Generator the Right Way
Once you have a transfer switch or interlock, sizing the generator is straightforward. List the circuits you need during an outage: furnace blower, well pump, refrigerator, freezer, lights, and a few outlets. Add up the running wattage of each load and the starting wattage of the largest motor (well pump or furnace blower, whichever is bigger). The generator must handle the combined running load plus the single largest starting surge.
For a typical rural home with a well pump (1 HP = 2,000 watts running, 6,000 watts starting), furnace blower (800 watts running, 2,400 watts starting), refrigerator (150 watts running, 600 watts starting), and lights and outlets (500 watts), the running load is about 3,450 watts and the largest starting surge adds 4,000 watts. A 7,500-watt generator handles this comfortably. A 5,000-watt generator can do it if loads are managed (do not start the well pump and furnace at the same time).
The generator connects to the house through a power inlet box, which is a weatherproof box mounted on the exterior wall with a twist-lock receptacle rated for the generator's output amperage. A heavy-duty cord (typically 10/4 or 8/4 SOOW) runs from the generator to the inlet box. From the inlet box, permanent wiring goes to the transfer switch or interlock breaker inside the panel. All connections use properly rated cord, plugs, and receptacles. No double-male cords. No extension cords plugged into outlets.
For outbuildings, the connection is the same: an inlet box on the building, a cord from the generator, and either an interlock on the subpanel or a transfer switch. If the outbuilding has its own meter and service, it needs its own transfer switch independent of the house. The generator can be portable and moved between buildings, but each building needs its own inlet box and switching device.
Generator Backfeed Safety Checker
Check if your generator setup is safe from backfeed risk. This decision-tree tool evaluates your transfer switch, connection method, and safety equipment against NEC Article 702 requirements and flags dangerous configurations.