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A home standby generator is a permanently installed unit that runs on natural gas or propane and kicks on automatically when the power goes out. The transfer switch senses the outage, starts the generator, and moves the house over to backup power, usually within about 30 seconds. And when utility power comes back, the system switches everything back over automatically.
That sounds pretty simple, and, once it’s installed, it is. The tricky part is figuring out what size generator you actually need, where it can go, what fuel makes sense, and which parts of your house you want running when the grid goes down.
Short answers
- Fuel: natural gas where distribution mains run, propane nearly everywhere else in the Black Hills.
- Sizing: driven by your 240 volt loads, above all the well pump, not by square footage.
- Heat: a propane or natural gas furnace still needs house power to run, so heat is usually the first load to cover.
- Placement: set by fuel distance, service distance, exhaust clearance, and where snow drifts.
- Timing: plan it before storm season, because demand spikes the week after every major outage.
Outages here are not brief. In December 2025, over twenty five thousand Black Hills Energy customers lost power in one night, with nearly eleven thousand still out the next afternoon, and the rural cooperative reported three quarters of its network down. Town tends to come back first. The farther you are from the main feeder, the longer you may be waiting. We handle standby generator installation throughout the region, and this is what the decision actually involves.
How the Transfer Switch Works, and Why It Matters
The transfer switch senses the outage, waits roughly thirty seconds, then starts the generator and moves the house over. The delay exists because power rarely fails cleanly in a storm, and you do not want an engine cycling through every flicker.
It is also a safety device. A properly installed transfer switch physically prevents your generator from backfeeding the utility lines, which protects the line crews working to restore them. That is why a generator is never connected through a cord into a receptacle, and why utilities repeat the warning about never running a portable unit indoors or in an attached garage.
Natural Gas or Propane
Your address has a lot of say in this. If natural gas lines already run to your property, it’s usually the simpler option. The supply is underground, so you don’t have to worry about keeping a tank topped up. However, if you’re outside the natural gas service area, propane is the practical alternative. In the Black Hills, that’s common, and many homes already have a propane tank supplying their furnace or water heater.
There is one important catch with propane: the tank is your fuel supply. A large generator can use more propane than you might expect when it’s working hard, and during a winter outage your furnace and water heater may be drawing from that same tank. In other words, tank size is something to figure out alongside the generator, not after you’ve bought one.
Sizing: Start With the Loads, Not the Generator
Picking the right size generator has less to do with how big your house is and more to do with what you want running when the power goes out.
A few big 240-volt loads can make a bigger difference than a handful of lights and outlets. Well pumps, air conditioning, electric ranges, dryers, and electric water heaters all need to be accounted for when you’re figuring out generator capacity.
For homes around the Black Hills, three loads tend to deserve particular attention:
- Heat. Even a gas or propane furnace needs electricity for the blower, igniter, and controls. No electricity means no furnace, regardless of how full the propane tank is.
- Water. If you’re on a private well, the pump needs electricity. Without it, you’ve got no running water, which can very quickly become a problem.
- Food. Your refrigerator and freezer may not be the biggest loads in the house, but keeping them running during a long outage is obviously useful.
Bigger is not better. An oversized generator costs more to install and can use more fuel than necessary. The goal is to match the generator to the loads you intend to run.
Your existing service is part of the answer. If the panel is full or the service is undersized for what the house already does, that gets handled first. Older homes in Deadwood, Lead and the established parts of Rapid City hit this often, since the service was sized for a house without a heat pump, a shop or a car charger on it. Sometimes the right first step is an electrical panel replacement, sometimes a service upgrade to 200 amp.
Where the Generator Can Go
Placement is set by four things, and it affects cost directly, since a longer run to the service means larger conductors under NEC ampacity rules.
- Distance to fuel. A short pipe run is simpler and cheaper than a long one.
- Distance to the electrical service. Longer runs mean larger conductors and more labor.
- Exhaust. A running engine produces carbon monoxide, so the unit cannot sit where exhaust can reach an operable window, a door, a dryer vent or a fresh air intake.
- Snow. A unit under a dumping roofline or on the drift side of the house gets buried in exactly the conditions you bought it for.
Maintenance
Standby units exercise themselves on a weekly schedule, running a short cycle of several minutes to circulate oil and prove the engine starts. Set that schedule for a time you are home, so you hear it. Beyond that, you’ll need oil and filter changes based on run hours, commonly around one hundred, along with the calendar-based maintenance schedule in the manual. Keep an eye on the starting battery, since cold weather is what finishes off a marginal one. It’s also worth checking the status lights every so often. A generator can only tell you there’s a problem if someone actually looks at it.
Storm season is also the right time to look at whole home surge protection, since restorations are hard on electronics.
Check Your Service Mast After a Wind Event
If the mast carrying utility conductors into your meter is damaged, you’ll need a licensed electrician to make the repair before the utility can safely restore service. After a serious wind event, walk outside and look at where the wires meet the house.
Why We Will Not Quote One Over the Phone
The price depends on what nobody can see from a desk: available fuel and its distance, what the existing service and panel can handle, which loads you want covered, where the unit can safely sit, and whether the well pump is in the plan. Two houses on the same road land in different places. We would rather look at it and give you a figure you can plan around.
Talk to us about backup power
We install and service whole home standby generators along with solar, EV and generator electrical systems, as electricians serving communities across the Black Hills and Rapid City.
Common Questions
How long does a standby generator take to start after the power goes out?
About thirty seconds. The transfer switch waits a short delay before calling for the generator, which keeps the unit from cycling during brownouts and brief flickers. The engine then runs a few seconds to reach full speed before the house transfers over.
Is propane or natural gas better for a home standby generator in the Black Hills?
If natural gas service is already available at your property, that’s usually the simpler option. Natural gas doesn’t need to be refilled, while propane gives you more control over your fuel supply but still makes tank size and important part of the decision. Propane is more energy rich per gallon, which is why units list a higher rating on it, but you own the supply, so tank size becomes part of the sizing decision.
What size standby generator do I need for my house?
It depends on which loads you want running, not on square footage. The heavy 240 volt loads drive the answer: well pumps, air conditioning, electric ranges, electric dryers and electric water heaters. A home on a private well almost always has to account for the pump, and a home with gas heat and gas cooking needs far less capacity than an all electric home of the same size.
Will a generator run my furnace if I heat with propane?
Your furnace needs electricity regardless of what it burns. The blower, igniter and control board all run on house power, so a gas furnace produces no heat during an outage without a source of electricity. That is why heat is usually the first load homeowners here want covered.
