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Power flickers, the house goes dark, and the humidity in your Marietta home climbs fast. You hear your new generator start up, but within seconds lights dim, breakers trip, or nothing comes on at all. In the middle of a storm, that is a terrible time to discover that something about the installation is wrong.
At Lightning Bug Electric, we have spent more than 25 years working on residential and commercial electrical systems in Marietta and nearby communities, and we see the same avoidable generator installation mistakes over and over. Our licensed, EATON-certified electricians are called in to fix failed inspections, nuisance shutdowns, and unsafe DIY setups. In this guide, we break down the most common generator installation mistakes in Marietta, why they happen, and what you can do to avoid them.
Why Generator Installation Mistakes Are So Common in Marietta
Marietta homeowners have good reasons to think about backup power. Summer thunderstorms, remnants of tropical systems, and tree damage are all common causes of outages in Cobb County. Add in the strain of heavy air conditioning loads during high heat and humidity, and many homes are already operating close to the limits of their electrical systems before a generator is even added.
Because of that pressure, it is tempting to rush into a generator purchase after a bad storm or choose the first installer with an open spot on the schedule. We often see units that were bought based on a quick online calculator or a sale price, then installed by a handyman or non-electrical contractor who treats it like a large appliance. That approach ignores the fact that a generator ties directly into your main service, and it has to work with whatever panel, wiring, and grounding your home already has.
Older homes around Marietta, especially in established neighborhoods, bring another layer of complexity. Panels may have been expanded or modified over the years, sometimes with DIY or outdated work behind the cover. When a generator is added without a thorough evaluation of those conditions, problems show up later during real-world loads or during inspections. Our team has seen plenty of installations that looked neat on the outside but hid undersized conductors, missing bonding, or improvised connections that would not hold up during a significant outage.
Mistake 1: Choosing the Wrong Generator Size for Your Home
One of the most common generator installation mistakes in Marietta is choosing a unit that is the wrong size. Many homeowners pick a generator based on a rough wattage number they saw online, or they choose a model that fits a budget without understanding what it can realistically power. This is how people end up with a generator that runs a few lights and outlets but cannot handle the air conditioner or other major loads when the outage hits in July.
Every major appliance in your home draws a certain amount of power, and some draw more when they start than they do once they are running. Air conditioning compressors, heat strips, well pumps, and some refrigerators have high starting, or inrush, currents. A generator that looks fine on paper for running watts can still stumble or trip breakers if those large loads all try to start while other circuits are active. In Marietta, where a 3 to 4 ton air conditioner is common, this is not just a theoretical problem.
Oversizing can cause its own issues. A much larger unit than you need costs more upfront and uses more fuel. On natural gas systems, it can also expose weaknesses in the gas line if the piping is not sized for that higher demand, which leads to surging or stalling when the generator is loaded. Bigger is not automatically safer or more reliable. The right choice is a generator that matches your real needs, your existing panel, and your fuel system.
Mistake 2: Skipping a Proper Transfer Switch and Backfeeding the Grid
Another serious generator installation mistake in Marietta is trying to connect a generator without a proper transfer switch or approved interlock. We still see situations where a portable generator is plugged into a dryer outlet or an improvised inlet, with the expectation that it will somehow backfeed power through the house. This might seem like a shortcut, but it is dangerous and often outside code requirements.
Without a transfer switch or interlock, your generator can send power not only into your home but also back out onto the utility lines. This is called backfeeding. If line crews are working to restore power and they think a line is de-energized, backfed power from a generator can put them at risk. It can also create a severe conflict when the utility restores power to a line that is being fed by your generator, which can damage the generator and connected equipment.
A correctly installed transfer switch physically separates your home’s circuits from the grid before generator power is applied. Power flows from the generator, through the switch, and into the selected circuits, while the utility connection is mechanically and electrically disconnected. An interlock kit provides a similar function at the panel by making it impossible to turn on the main breaker and the generator breaker at the same time. In both cases, there is a clear, enforced path for current that keeps your home and the grid isolated from each other.
Mistake 3: Poor Generator Placement That Creates Safety & Code Problems
Placement is another area where generator installation mistakes in Marietta show up again and again. We see units installed in tight corners under windows, next to crawlspace vents, or directly beside bedroom walls. The goal might have been to hide the equipment or tuck it out of the way, but those choices can create serious carbon monoxide and heat issues.
Generators produce exhaust that contains carbon monoxide, which can pool or be drawn into the home if the unit is too close to doors, windows, or vents. It does not take a large opening for fumes to find their way into a living space, especially if the generator runs for hours during an extended outage. Manufacturer instructions and codes typically require clearances from these openings, as well as from combustible walls and structures, to reduce those risks.
Clearance is about more than exhaust. Generators also need airflow to cool the engine and alternator. Crowding equipment between walls, fences, or dense landscaping restricts that airflow and traps heat. In Marietta’s summer climate, with high temperatures and humidity, inadequate ventilation can shorten the life of the generator and increase the chance of nuisance shutdowns. It also makes maintenance and repair more difficult if there is not enough room to safely access panels and service points.
Mistake 4: Ignoring Fuel Supply, Ventilation, and Run-Time Limits
Fuel decisions are easy to overlook until an outage lasts longer than expected. Another common generator installation mistake in Marietta is choosing a fuel source based solely on convenience or initial cost, without thinking through how it will behave under load or during extended operation. This can lead to generators that starve for fuel, run irregularly, or rely on unsafe storage practices.
On natural gas and propane systems, the size and length of the gas line have a direct impact on performance. When a generator starts and accepts load, it needs a steady supply of fuel at the correct pressure. If the piping is too small or too long for the unit’s demand, the motor can surge, bog down, or stall, especially when a large load like an air conditioner kicks on. This often shows up only during real-world tests, not when the system is idle.
Portable generators present different challenges. Storing gasoline in garages or sheds near ignition sources, or placing the generator just inside a garage with the door cracked for ventilation, can allow exhaust to migrate into the home. Propping a unit under an overhang or too close to walls to keep it out of the rain can also trap fumes. In a dense neighborhood, poor placement and exhaust management can impact neighbors as well as the homeowner.
Reliable generator operation starts with a fuel plan that matches your installation. That might involve verifying that your gas meter and piping can support the generator’s peak demand, or planning safe storage and refueling practices for portable units. Our team at Lightning Bug Electric evaluates fuel supply during the design phase, coordinates with fuel providers where needed, and follows current guidance on safe operation. Our training, including EATON-related education and exposure to modern energy systems, helps us spot fuel and ventilation issues before they lead to failure during a storm.
Mistake 5: Overlooking Panel Condition, Grounding, and Surge Protection
Many homeowners focus on the generator itself and forget that it has to work with the panel and wiring that are already in place. In older Marietta homes, that existing infrastructure can be the weak link. Connecting a new generator to an aging or modified panel without a careful review is another generator installation mistake that can create safety gaps and equipment damage.
Grounding and bonding are key parts of any electrical system, especially when a second power source like a generator is added. Grounding provides a path for fault current to return safely, and bonding ties metallic parts together so they stay at the same potential. If these elements are missing or incorrect, a fault during generator operation can energize metal surfaces or leave protective devices less effective. This is not something you can see just by looking at the outside of the panel.
Modern homes also contain many sensitive electronics that do not handle voltage spikes well. The transition between utility power and generator power, as well as motor loads starting and stopping on generator power, can create brief surges or voltage fluctuations. Without appropriate surge protection at the panel or on specific circuits, those events can shorten the life of appliances, HVAC equipment, and electronics like televisions and computers.
Our team at Lightning Bug Electric handles generator projects with permitting and inspection in mind from the start. Over more than two decades in Marietta, we have built a reputation for safe, code-conscious work, reflected in recognition such as Angie’s List Super Service Award, Kudzu’s “Best of 2014,” and an A+ BBB rating. We view inspections as an important checkpoint, not an obstacle, and we structure our installations so they stand up to that review and serve your home reliably.