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You spent real money on a standby generator. Maybe it was a Generac, a Kohler, or a Briggs & Stratton. You had it professionally installed, you’ve run the weekly exercise cycle, and when a storm finally rolls through Central Indiana, and the grid goes dark, you expect it to handle everything. Then it doesn’t. Half the house goes dark. Certain rooms have no power. Appliances that should be running are sitting silent.
So what’s actually going on?
This is one of the most common generator complaints we hear from homeowners across Indianapolis, Carmel, Fishers, Noblesville, and Greenwood. If you’re wondering why your generator isn’t powering your whole house, it usually comes down to one of three things: available output, wiring, or fuel supply. And most of the time, there’s a clear, fixable answer. A standby generator that can’t sustain power to the entire home is rarely broken outright. It usually points to something specific, and knowing where to look makes a real difference when you’re standing in a dark house during a storm.
The Generator Is Running, But Not Covering Everything
First, a whole-house generator losing power to certain circuits doesn’t always point to the generator itself. Several systems have to work together to provide backup power to every room, and any one of them can be the weak link, even when the generator is running fine. We see this regularly. And in most service calls, the generator itself is not the issue. We usually start with the transfer switch before we look at anything else.
Where do things go wrong? Here are the six most common culprits.
- The Transfer Switch Is Only Covering Part of Your Home
The automatic transfer switch (ATS) is the component that senses a power outage, disconnects the utility feed, and signals the generator to take over. But how your transfer switch is wired determines exactly which circuits receive backup power.
Some installations connect only a portion of the main electrical panel via the transfer switch. That’s sometimes a cost decision made at the time of installation, or the original job was scoped to cover only essential circuits. The generator itself might be perfectly capable of handling more load. Still, if the partial transfer switch installation leaves certain breakers off the backup circuit, those rooms go dark regardless of how well the generator performs.
Manual transfer switches have their own physical limitations, too. They often can’t provide full-panel coverage like an automatic transfer switch can. If the transfer switch isn’t set up to handle your home’s full circuit load, have a certified technician verify the wiring first. That step alone can save a lot of wasted troubleshooting.
- The Generator's Wattage Capacity Is Being Exceeded
Every standby generator system has a rated output capacity, measured in kilowatts. A 14kW unit, for example, can only supply so much power at any given time. If your home’s peak electrical demand during an outage pushes past that output, the system has to respond somehow. The generator will either shed load automatically, trip a breaker in the main electrical panel, or shut off entirely when the load spikes past what the unit can handle. This is different from load shedding, which we’ll cover next. Here, the generator isn’t deliberately managing demand. It has simply exhausted its available output.
Generator sizing is a more common issue than most homeowners expect. This one catches people off guard. A home that was sized for a 14kW generator a decade ago may have since added a heat pump, an EV charger, a hot tub, or other high-draw equipment. The electrical load calculation that justified the original size no longer reflects the house’s actual needs.
If your standby generator shuts off when demand rises, or trips when you run the AC and a few other things at once, the unit probably can’t keep up with what the house is pulling now.
- A Load Management System Is Prioritizing Circuits
Some whole-house generator systems include a load-shedding component or load management system that actively monitors power consumption and drops lower-priority circuits when demand exceeds capacity. Unlike a sizing problem, this is intentional. The system protects the generator from overload by temporarily cutting power to certain areas of the home while keeping critical circuits running. The generator isn’t failing. It’s making a decision.
If the backup power system isn’t reaching certain rooms during heavier usage, load shedding doing its job may be the explanation. The real question is whether the system is set up the way you actually want it today. Priority assignments made years ago often don’t reflect how a household runs now. A qualified technician can pull up the load distribution settings and make adjustments.
- Fuel Supply Is Limiting Generator Performance
A standby generator running on propane or natural gas depends on consistent fuel pressure and volume to produce its rated output. If the propane supply pressure drops, or if the natural gas supply line to the generator is undersized, the unit’s power generation starts to fall short under real conditions. It won’t always shut off completely. Sometimes it just starts losing ground.
This is more common with propane systems during cold Indiana winters, when fuel delivery can be delayed, and tank levels drop lower than they should. A generator that performs fine under moderate draw but starts fluctuating or dropping voltage as more circuits come online is often dealing with a fuel supply restriction rather than a mechanical failure.
If the generator holds steady early in an outage but starts struggling as more appliances kick on, check the fuel system first. It’s a step that’s often skipped, and it explains a lot of these partial-power situations.
- A Circuit Breaker Issue Is Preventing Full Coverage
Sometimes the problem isn’t the generator at all. A tripped breaker inside the main electrical panel, the generator’s breaker panel, or the transfer switch panel can cut power to a section of the home while everything else continues running normally.
After an outage begins, it’s always worth checking whether a breaker has tripped in any of these panels. A generator breaker tripping under load is common when demand spikes quickly, such as when air conditioners, refrigerators, and water heaters all cycle on at the same time. Resetting it may bring power back to that section of the house. But if it keeps tripping, something deeper is going on, and it’s time to call a technician.
- The Generator Has a Performance Issue That Needs Attention
If none of the above apply, the generator itself may have a developing performance problem. This is different from a sizing issue or load shedding. Unlike a capacity problem, this happens even when the generator was originally adequate for the home. The unit may have handled everything fine for years, but internal wear or skipped service has gradually pulled down what it can actually put out.
Units that go extended periods without routine maintenance can develop issues with the voltage regulator, carburetor, or fuel system, reducing actual power generation well below the nameplate rating. We check these components first on service calls where the generator runs, but the electrical output isn’t reaching all circuits. It narrows things down fast.
If a generator handled previous outages without trouble but now struggles, it’s telling you something. And honestly, this is where most people get stuck. Unusual noises during operation, fluctuating power, or fault codes on the display are worth taking seriously. These aren’t random. They’re the system telling you maintenance got skipped one too many times.
Regular oil changes, filter replacements, battery checks, and fuel system inspections set a generator apart from one that almost works when you need it. There’s a big difference between the two at 2 am during a January ice storm.
What a Whole House Generator Can Actually Run
People ask this a lot, and the answer is straightforward. A properly sized standby generator system, installed by a licensed electrician and connected to a full-automatic transfer switch, should power your entire home. HVAC, refrigerators, lighting, outlets, sump pumps, water heaters, and most standard appliances running at the same time. That’s what these systems are built for.
Where it gets more specific is size. A 22kW whole-home generator carries far more than a 10kW unit. A generator tied to a full-panel automatic transfer switch covers more than one circuit, whereas a generator tied to a selected-circuit automatic transfer switch covers only one circuit. And a system that gets serviced on schedule produces consistent output that a neglected one simply won’t.
For most Indiana homeowners who had their system sized and installed correctly and kept up with service, the generator handles everything without much drama. When it doesn’t, something in that chain is off.
How to Address a Generator Partial Power Problem
If you’re trying to figure out how to fix a generator that isn’t powering everything, start with the basics before assuming the unit itself has failed. Check whether any breakers have tripped in the main electrical panel or the transfer switch panel. Sometimes that’s all it is. From there, confirm that your transfer switch covers the entire home and not just a selected set of essential circuits. If you’re running propane, verify the tank level and check the regulator pressure before concluding the generator has a mechanical problem.
If none of that turns anything up, and the generator is still shutting off or leaving rooms dark, call a certified technician. Generator partial-power issues go in several directions depending on the root cause, and guessing wrong usually means spending money on the wrong fix. Someone who can look at the fuel supply, engine output, transfer switch wiring, and breaker panels together gets to the answer a lot faster.
This is the kind of problem we deal with regularly across Central Indiana. Whether it’s a Generac not covering all circuits, a Kohler system that trips under heavy load, or a Briggs and Stratton unit producing inconsistent output, our team knows where to look and how to fix it.
We cover generator repair, transfer switch service, load calculation assessments, and full system inspections across the Indianapolis area, including Carmel, Fishers, Noblesville, and Greenwood. Every job is done to code by technicians who work on these systems every day.
If your generator isn’t holding up during outages, that’s a problem worth solving now. Don’t wait until the next outage exposes the same issue. Call us at (317) 831-8677 or request an appointment online to get a diagnostic scheduled with one of our certified technicians.
FAQs
Why is my generator not powering my whole house?
Usually, it’s one of four things: the transfer switch only covers part of your electrical panel, the generator is undersized for what the house pulls now, a breaker has tripped somewhere in the system, or a fuel supply issue is cutting output. A technician can sort through those quickly once they see the full setup.
Is it normal for a generator to not power everything in the house?
Not if the system was set up to cover the whole home. Partial coverage usually means either the transfer switch wasn’t wired for the full panel, or the unit doesn’t have enough output for everything running at once. Either way, it’s not something you just live with.
What can a whole house generator actually run?
If it’s sized right and wired through a full-panel transfer switch, it should run everything, including HVAC, refrigerators, water heaters, sump pumps, lighting, and outlets. All at the same time. A licensed electrician can run a load calculation to confirm whether your current setup matches the required load.
Why does my generator only power part of my home?
Nine times out of ten, it’s the transfer switch. If only selected circuits run through it, only those circuits get backup power. The generator itself can be running fine while half the house stays dark. Worth having someone check the wiring before you assume anything is wrong with the unit.
How do I fix a generator that isn't powering everything?
Start simple. Check for tripped breakers in the main panel and transfer switch panel. If those are clear, you need a technician to review the load calculation, transfer switch coverage, and the fuel system together. Guessing at the cause usually means fixing the wrong thing.
Can a fuel issue cause my generator to lose power to some circuits?
Yes, and it’s one of the more common things that gets overlooked. Low propane pressure or a natural gas line that’s too small for the generator will restrict output once the load climbs. The unit runs fine at first, then starts dropping voltage or cutting out as more things come on. Check the tank and regulator pressure before calling it a mechanical problem.
How often should a standby generator be serviced?
Annually at minimum. Some systems need it twice a year, depending on run hours. Generators that miss service are consistently the ones that fail mid-outage. It’s not a coincidence.
Does Midwest Generator Solutions service all generator brands?
Yes. We work on Generac, Kohler, and Briggs & Stratton standby generators throughout Central Indiana, including Indianapolis, Carmel, Fishers, Noblesville, and Greenwood.