Standby Generator Cost — Installed, Line by Line

A whole-house air-cooled standby typically runs $8,000 to $15,000 installed, and the defaults here — a 22 kW set with a 200 A service-rated transfer switch, 40 ft of gas, a precast pad and 16 hours of labor — land at $10,990. Small essential-circuits systems start near $6,500; liquid-cooled sets above 26 kW pass $20,000 quickly. The single biggest driver after the machine is the transfer switch.

Because a standby is five trades in one job. The transfer switch is $700 to $3,200 depending on whether it is a small essential-circuits panel or a 400 A service-rated switch. The fuel run is plumbing at roughly $28 per foot for natural gas. There is a pad, a permit and usually two inspections, and a day or two of labour across electrical and gas. On a 10 kW set the installation is around 62% of the total, and the machine only becomes the majority of the invoice at 22 kW and above.

That is a load question, not a cost one, and it is usually decided by motor starting rather than running load — a house drawing 9.2 kW running can need a 20 kW set purely to start its air conditioner. Work it out first with the Generator Sizing Calculator, because moving one size down usually saves more than every other line item combined.

No, and this is the cheapest real decision on the job. A service-rated whole-house switch transfers everything and costs $1,600 to $3,200. An essential-circuits switch backs up eight or ten selected circuits for $700 to $900. Better still, NEC 702.4(B)(2) permits a generator that cannot carry the full load where automatic load management sheds the rest — which frequently lets a smaller machine and a cheaper switch do the same practical job.

Natural gas if the street has it. The run costs about the same per foot, but propane adds a buried tank at roughly $1,200 plus refills, and a generator on LP derates slightly against its natural-gas rating. Natural gas has no tank, no delivery, and no runtime limit — which matters most in exactly the multi-day outage a standby exists for. Propane wins only where there is no gas main.

Almost always two, and sometimes three: electrical, gas or plumbing, and in many jurisdictions a mechanical or zoning review for the set's placement. Placement rules are stricter than people expect — manufacturers require clearance from openable windows, doors, and combustible walls, and local ordinances may add property-line setbacks and noise limits. Confirm placement before quoting; discovering it at install is expensive.

Budget for annual service at $200 to $500 — oil, filters, plugs, valve check — plus the fuel the weekly self-test burns, typically 10 to 20 minutes running. Batteries last three to five years. None of that appears in an install quote, and over a fifteen-year life the maintenance total is a meaningful fraction of the original purchase.

Substantially — a quality portable plus an inlet box and a listed panel interlock kit is usually $1,500 to $3,000 installed against $11,000 for standby. The trade-offs are that someone has to be home to start it, refuel it every few hours, and it will not carry a whole house. What matters for safety is that the interlock is listed for that specific panel: a homemade one or a suicide cord backfeeds the utility line and can kill a lineman.