Standby generators are sold on the unit price, and the unit price is the part of the total that varies least. Two houses buying the identical generator can pay very different amounts to have it working, and the difference is decided before anyone opens a catalogue.
Four costs, not one
- The generator. Priced by output. The one number people compare, and rarely the one that separates two quotes.
- The electrical work. Transfer switch, connection to the service, any subpanel for selected circuits, commissioning. This is the electrical contractor’s scope and where most of the variation lives.
- The gas work and the base. Usually separate trades. Real money, and frequently the thing that sets the schedule.
- Permits, inspection and utility coordination. Set locally.
A quote covering only the first is not a quote for a working generator. Establishing which of the four each bidder has included is the whole job of comparing them.
Sizing is calculated, not guessed from square footage
Sizing comes from the loads the generator has to start and run — not from the size of the house. The distinction matters because motor loads behave badly at startup: an air conditioning compressor or a well pump can draw several times its running current for a moment as it kicks in, and that momentary peak is usually what sets the required size.
In this part of Oklahoma the air conditioning is normally the deciding load. A house that wants the AC running through an August outage needs a materially bigger unit than the same house willing to do without it.
Undersizing does not fail gracefully. The generator stalls or trips when the load it cannot start tries to come on, which tends to happen at the worst moment — so this is not a place to economise by rounding down.
Whole-house or selected circuits
This is the single largest lever you control, and it changes both the unit and the installation.
Whole-house carries everything. Simplest to live with, most expensive to buy and install.
Selected circuits feeds a subpanel with the circuits you have chosen — typically heating and cooling, refrigeration, a well pump if you have one, some lighting and outlets. Cheaper unit, cheaper install, and for most households genuinely the better value. The trade is that you decide in advance what matters.
There is a middle route worth asking about: load management. A device that sheds large loads automatically lets a smaller generator cover more of the house, because the AC and the range are never allowed to draw at once. It often costs less than the next generator size up.
The transfer switch
The component that decides which supply the house is connected to, and the one part of the installation that is not optional. It disconnects the house from the utility before connecting the generator — which is what stops the generator pushing power back onto the network.
Automatic switches detect the outage and change over on their own, including while you are away. Manual switches you operate yourself, and cost less. Whether the difference is worth it depends on whether anyone is reliably home, and whether anything in the house — a freezer, medical equipment, a sump pump — cannot wait for someone to flip it.
What the panel adds
The transfer switch has to be integrated with the existing service, and a selected-circuit installation means moving circuits into a subpanel. Both need somewhere to land.
A panel that is full, damaged, or an obsolete type is likely to need addressing first — which turns one project into two. This is the most common reason a generator quote comes back higher than expected, and it is much better discovered at the survey than on installation day. What panel work costs
If an EV charger is also on your list, scope both at once. The service work happens once rather than twice, and the saving is real. EV charger installation cost
Fuel supply and siting
Natural gas or propane, and the two are not equivalent on cost. Natural gas needs a supply of adequate capacity run to the unit — a longer or upsized run is gas-fitting work, not electrical. Propane needs a tank, which is either a purchase or a rental with an ongoing cost.
The generator also needs a level base and has to sit at a compliant distance from windows, doors and vents, with clearance for servicing. A straightforward side-of-house position is cheap. A position that needs the pad building up, a longer gas run, or a longer electrical run back to the service is not.
Permits, inspection and the utility
Work that ties into the service normally requires a permit and an inspection, and the contractor pulls it. Where the service arrangement is affected, the utility is involved and works to its own schedule rather than yours — which affects the timeline more than the cost. How permits work in Lawton
What it costs to own, not just to fit
Standby generators self-test on a schedule, which uses a little fuel every week and is the thing that tells you it will start when needed. Beyond that: the engine has a manufacturer servicing schedule, and the starting battery is a consumable — a flat battery is one of the most common reasons a generator does not come on.
Budget for servicing from the beginning. A generator that has not run in a year is a generator that may not run at all, which is an expensive way to discover a maintenance gap.
The portable alternative
A portable generator plus a properly installed inlet box and transfer switch costs a fraction of a standby installation and covers a handful of circuits. You have to be home, you have to start it, and you have to keep fuel — but for occasional outages it is a legitimate answer rather than a compromise.
The electrical work is the same principle at smaller scale: the inlet and transfer switch are what make it safe. That part is not where to save money.
Reading two quotes properly
- Same generator output? A quote for a smaller unit is not a cheaper quote for the same job.
- Whole-house or selected circuits — and if selected, which circuits?
- Automatic or manual transfer switch?
- Is a subpanel included where selected circuits require one?
- Is panel or service work included, or excluded and unmentioned?
- Who is doing the gas and the pad, and is it in this price or someone else’s?
- Permit, inspection and commissioning included?
- Is there a service plan, and is the first year in the price?
Two quotes that look far apart usually differ on the sizing or on who is doing the gas. Both are worth asking about directly before assuming one contractor is expensive.
Generator installation — what the work involves · How electrical pricing is structured