Your Generator Is Running but the House Has No Power

The engine is running. You can hear it. But the lights are out, the fridge is silent, and the well pump isn't moving. A running generator and a dark house means the electricity is being made — or not made — and then failing to reach your panel somewhere along the way. The break is almost always in one of a handful of places: a breaker or GFCI on the generator, a transfer switch that never engaged, a cord or inlet fault, an overload, or the generator's own internals. Work the checks in the order below — easiest and safest first — and stop the moment a check moves you past the panel cover.

The triage at a glance

The order is deliberate: it runs from the checks you can do in thirty seconds with no tools to the ones that belong to a dealer. It is not a ranking of what goes wrong most often — it is the order that wastes the least of your time in a dark house.

Is it just exercising?

Maybe nothing is broken at all. A standby generator runs a weekly self-test — usually about 20 minutes — and during that exercise it deliberately does not transfer power to the house. Generac's Guardian controllers with Evo 1 or Evo 2 controls do not power the home during an exercise, and Kohler's unloaded exercise is the same: the generator runs, the load stays on utility. If the power is out in the neighborhood and your standby is running but the house is dark, check the control panel first: if it says it is exercising, or if the run started at its usual weekly time on a day the grid is actually fine, wait it out. The test ends on its own in about 20 minutes.

The giveaway is context. An exercise happens on schedule, on a day when the utility is up. A real outage has the neighbors dark too, or the utility's outage map showing your address. If the grid is genuinely down and the generator has been running for more than a few minutes without transferring, it is not the exercise — move on to the next check.

Is the generator actually making power?

Before you blame the house wiring, find out whether power is leaving the generator at all. The test is different for the two generator types, and it takes about a minute.

Portable generator: unplug everything from it, then plug a single known-good load — a lamp, a radio — directly into one of the generator's own outlets, with no extension cord in between. If the lamp lights, the generator is making power and the problem is downstream: the cord, the inlet, or the switch. If the lamp stays dark on every outlet, the problem is at the generator itself — a breaker, a GFCI, or something internal. Generac's own troubleshooting guide starts exactly here: start the generator with no loads connected, then test the output.

Standby generator: check the Main Line Circuit Breaker (MLCB) on the generator itself. Generac's support documentation is blunt about this one: if the MLCB is in the OFF position while the generator is in AUTO mode, the generator will start — and the automatic transfer switch will not transfer, because it needs generator power to move to the standby position. Flip the MLCB to ON and give the switch its normal warm-up time. If the MLCB was already ON, or the switch still doesn't move after a few minutes, the transfer side is the problem, not the engine.

Did a breaker or GFCI trip?

A generator has two different things that can cut its output, and they trip for different reasons. A circuit breaker trips on overcurrent — you asked for more amps than the circuit can give. A GFCI receptacle trips on leakage — current escaping to ground through water, worn insulation, or a defective appliance. Both can leave the engine running with nothing coming out of the outlets.

Check the generator first. Look for its breaker(s) — usually push-button or toggle breakers on the control panel — and for GFCI outlets with TEST and RESET buttons. A GFCI that has tripped will have its RESET button popped out; press it once. Reset a tripped breaker or GFCI once. If it trips again immediately, stop. A breaker that will not stay reset is telling you there is a fault or an overload, and repeatedly resetting it is how equipment gets damaged and people get hurt.

Then check the house panel. A tripped breaker does not always look off — it often sits in a middle position, between ON and OFF. Push it fully to OFF, then firmly back to ON. If it trips again right away, leave it off and call an electrician: that is a short or an overload in that circuit, not a generator problem. Only check the panel if the area is dry and you are comfortable doing it — and never remove the panel's dead-front cover. The breakers are the homeowner's part; everything behind the cover is the electrician's.

Is the transfer switch actually in the GEN position?

This is the most common "nothing is broken" answer in the whole article, and the easiest to miss in the dark. The transfer equipment is the gate between the generator and the house, and if it never moved, nothing downstream can have power.

Manual transfer switch or interlock (portable generators): the switch has to be moved by hand, and it has to go all the way. A handle left partway between LINE and GEN can leave the house with no power at all — confirm it is fully in the GEN position with a firm click. With an interlock kit, the sequence matters: main breaker OFF, slide the plate, generator breaker ON. If the main is still on, the interlock physically blocks the generator breaker from closing, which is the safety mechanism working as designed — it just looks like a failure from the kitchen.

Automatic transfer switch (standby generators): the switch needs two things to move — voltage from the generator and voltage on its transfer circuit (Generac's 194/23 control wires). If the generator is running and the MLCB is on but the switch hasn't moved after its warm-up delay, the communication path is suspect. Generac's switches carry three fuses protecting those sensing and control wires, and a blown fuse — or a loose or corroded control-wire connection — breaks the conversation between the generator and the switch. Kohler's manuals describe the same failure mode from the other side: a "Failure to Transfer" warning when the transfer signal is sent and the switch never confirms the move. Fuses and control wiring are dealer work. Generac is explicit that the switch enclosure contains live wires and is dangerous, and that untrained owners should not attempt to service internal generator wiring. Your job is to identify that the switch is the suspect and call the dealer with that information — not to open the box.

One more possibility on the automatic side: the switch can be operated manually in an urgent outage, but only after reading the manual for your specific switch. It gets power to the house without fixing the underlying problem, and the procedure exists for exactly this situation. Do not improvise it.

Is the cord or inlet the problem?

If a lamp plugged directly into the generator lights up but the house stays dark, the break is in the connection between the two. Work the cord end to end.

First, confirm the cord is actually the right one. A house inlet is fed through a 4-wire 240V twist-lock — the L14-30 — with two hot legs, a neutral, and a ground. A plain 3-prong 120V cord plugged into the wrong place cannot feed a 240V inlet properly, and a cord rated for fewer amps than the generator's outlet limits how much power can reach the house at all. The cord, the inlet, and the breaker feeding the inlet all need to match the generator's largest outlet — 30 amps means a 30-amp cord and inlet, not a 20-amp one pressed into service.

Then check the physical connection. Twist-lock plugs have to be pushed in and turned until they lock; a plug that looks seated but never locked can vibrate loose under load. Inspect both ends for heat damage, melted plastic, bent prongs, or green corrosion, and check the cord itself for cuts or crushed sections. A cord that has been run over by a vehicle or pinched in a door is a suspect even if it looks intact. If you have a second cord, swap it in — a known-good cord eliminates the question in one move. Generac's troubleshooting guide lists a poor connection or defective cord set as a first-line cause of no output, and suggests testing the cord on a known power source to rule it out.

If the cord checks out and the house is still dark, the fault is inside the inlet box or the wiring between the inlet and the switch. That is electrician territory — the inlet is hardwired into the panel, and diagnosing it means working in live equipment.

Are you simply overloading it?

An overloaded generator does not always stall. Often it runs, sounds rough, and trips its breaker the moment a big load starts — or it bogs down under load while running perfectly with nothing plugged in. Generac's quick-reference guide names this exact symptom: engine runs well at no load, bogs when load is applied, cause is overload, solution is reduce the load.

The usual culprit in a rural house is the well pump. Its starting surge is several times its running watts, and it can trip a breaker before the steady-state numbers look excessive. A refrigerator compressor or a furnace blower starting at the same moment makes it worse. And the limit is per-outlet, not just total: a 120V, 20-amp receptacle is limited to 2,400 watts even if the generator can produce much more through all its outlets combined. Plug the pump's circuit into a 20-amp outlet and ask for more, and that outlet's breaker trips while the generator keeps running.

The fix is the isolation test. Shut the generator down, disconnect every load, restart it with nothing connected, and reset the breaker or GFCI once. Then plug in one known-good load directly — a lamp — and confirm it holds. Add loads back one at a time, in the order that matters: lights and fridge first, the well pump on its own, then the rest. The load that kills the power is the load that is too much, and now you know whether you need to shed something or whether the generator is simply too small for the job. If the breaker trips with nothing connected at all, stop — the breaker, the receptacle, the wiring, or the generator itself is faulty, and that is a service call. Our generator sizing guide and the generator size calculator walk through the wattage math so the next outage does not repeat this one.

Do some circuits work but the 240V loads don't?

This is a different symptom from a fully dark house, and it points at a different break. If some lights and 120V outlets work but the well pump, the electric water heater, the stove, or the dryer are all dead, one of the two 120V legs that make up your 240V service is missing. Residential 240V is two 120V legs together — the utility sensing wires in an automatic transfer switch are literally two 120V lines — so losing one leg kills every 240V load and half the 120V circuits while the other half looks fine.

The cause is usually a breaker with one pole open — Kohler technicians have traced exactly this to a generator breaker with an open phase — or a failed connection in the transfer switch or the inlet wiring. This is not a homeowner diagnosis beyond noticing the pattern. If half the house works and every 240V load is dead, note which circuits are out, write it down, and call an electrician or the generator dealer. The pattern is the diagnosis, and it saves the pro real time. The well pump is the load that makes this urgent at a rural house — it is a 240V load, so a missing leg means no water even while the lights are on. Our well-pump generator guide covers the 240V requirement that portable generators often miss.

Is it load management, not a fault?

Some circuits may be off on purpose. Automatic transfer switches with load management deliberately shed heavy loads when the generator approaches its limit — Generac's Smart AC Module, for example, manages up to four HVAC loads on priority levels so an air conditioner kicking in does not trip an undersized unit into overload. If your standby system has load management and some circuits are dark while others run, check whether the dark ones are the managed loads before assuming a failure. The switch is protecting the generator, not failing. The transfer switch guide explains how load management fits into the switch options.

What if the generator itself isn't making power?

You have checked the breakers, the GFCI, the switch position, the cord, and the load — and a lamp plugged straight into the generator still stays dark on every outlet. At that point the fault is inside the generator, and the remaining diagnosis is not a homeowner job.

The usual internal suspects are the automatic voltage regulator, the brushes and slip rings, or the stator and exciter windings. Overloading a generator can burn out a voltage regulator; a machine that has sat unused for a long time can lose the residual magnetism in its field, and worn brushes or dirty slip rings break the excitation circuit. Technicians test these with a multimeter — resistance across the slip rings, voltage at the brushes — and replace the regulator or brushes when the readings are out of range. Generac's own troubleshooting table ends this branch in one line: fault in the generator, contact an authorized dealer. Do not open the generator to test these parts, and do not attempt field-flashing procedures you found in a video. The parts are cheap; the testing requires the covers off and the engine running, and that combination is how people get hurt.

When to stop and call a professional

Stop and call an electrician or the generator dealer — whichever owns the piece that failed — when any of these are true:

• A breaker or GFCI trips a second time right after you reset it, or will not reset at all with no load connected.
• The breaker feels hot, you smell burning, or you see arcing or melted plastic anywhere — generator, cord, inlet, or panel.
• The automatic transfer switch has not moved and the MLCB is on. Fuses, control wiring, and the transfer mechanism are dealer work.
• Half the house works and every 240V load is dead. That is a missing leg, and the diagnosis is in the panel or the switch.
• A lamp plugged directly into the generator stays dark on every outlet. The fault is internal.
• Anything about the job requires opening a panel cover or a switch enclosure, or working on wiring you cannot see both ends of.

When you call, bring the pattern, not just the complaint: which generator, portable or standby; whether a lamp works directly in the generator's outlets; which breakers you reset and whether they held; whether the transfer switch moved; which circuits are out and which work. That is the difference between a diagnostic visit and a fishing expedition.

When a running generator won't help

A running generator is not a universal fix, and it is worth knowing where its limits are before the next outage.

• It won't fix the grid. If the outage is on the utility side and your switch never transfers, the generator can only feed the circuits wired through it. Extension cords to individual appliances are the fallback, and they cannot feed hardwired loads like a well pump or a furnace blower.
• It won't add watts. An undersized generator is still undersized behind a perfect switch. Load management only goes so far, and the honest fix is a bigger machine or fewer loads.
• It won't make fuel. An automatic transfer does not create propane or gasoline. Your runtime is still your tank, and a generator that runs out of fuel mid-outage is the same dark house with a different cause.
• It won't fix a dead battery on a standby. The weekly exercise exists partly to keep the starting battery charged. A standby that cranks weakly or not at all during an outage is usually a battery problem, not an engine problem — and that is a different article.
• It won't forgive a bad connection. A corroded inlet, a loose control wire, or a switch that has never been tested under load will fail exactly when you need it, regardless of how faithfully you changed the oil.

Keep it from happening again

The weekly exercise proves the engine starts. It does not prove the transfer switch will move, and it does not prove the generator can carry your house. The test that proves both is a load transfer test: once or twice a year, simulate an outage — turn off the main breaker, let the generator start and transfer, and run the house on generator power for 20 to 30 minutes under real load. If the switch hesitates, transfers only part of the load, or fails after ten minutes of heat, you have found the failure on a Saturday afternoon instead of during a storm. Our power outage playbook covers the first ten minutes of a real outage, and the transfer switch guide covers what the switch should be doing in the first place.