What Size Whole-Home Generator Do I Need? A NJ Guide
Most New Jersey homes are well covered by a 22–26 kW whole-home standby generator, while a smaller 10–18 kW unit paired with smart load management can run just your essentials for less. The right size depends on what you want to keep running when the power goes out.
Whole-home vs. essential circuits
There are two ways to size a standby generator:
- Whole-home coverage. The generator runs practically everything — central AC, heat, well pump, kitchen, and outlets — as if the grid never went down. For most NJ homes that means roughly 22–26 kW.
- Essentials only. A smaller unit (10–18 kW), often with smart load management, powers the critical stuff — heat, refrigerator, well pump, sump pump, and some lights and outlets. It costs less and still keeps your home safe and livable.
How generators are sized
Sizing comes down to the largest loads that will run at once. The heavy hitters in most homes are central air conditioning, electric heat or a heat pump, a well pump, an electric range, and — increasingly — EV charging. A well pump and an AC compressor also need extra “surge” power to start. Rather than guess, we do a proper load calculation at your home so you’re not paying for more generator than you need — or ending up with too little.
Standby vs. portable
A portable generator is cheaper up front but has to be rolled out, refueled, and connected manually every outage, and it only powers a few things. A standby generator is permanently installed, runs on natural gas or propane, and starts automatically within seconds of an outage — you don’t even have to be home. For NJ homeowners who lose power in storms, standby is the set-and-forget option.
What does a whole-home generator cost?
Most whole-home standby installations in New Jersey run about $8,000 to $15,000 installed, depending on the size of the unit, the transfer switch, the gas hookup, and the electrical work involved. As always, we give you the exact price up front. If your electrical panel is older or undersized, it may need attention as part of the job.
What’s involved in the install
A standby install includes setting the unit on a pad, running the gas line, wiring the automatic transfer switch to your panel, permitting, and startup and testing. We pull the permit and handle the inspection, and we’re an authorized Generac installer.
Frequently asked questions
What size whole-home generator do I need?
It depends entirely on whether you want the whole service backed up or only the circuits that matter. Backing up heat, the refrigerator, the sump pump, a well pump, some lighting and outlets is a far smaller and cheaper unit than one sized to carry central air conditioning and an electric range at the same time. We walk the panel with you and price both rather than selling you the biggest one.
How are standby generators sized?
By adding up the running load of the circuits you want covered, then accounting for the starting surge of the largest motor, which is usually the air conditioning compressor or a well pump. Motors draw several times their running current for the first moment. Sizing on running load alone is the most common mistake and produces a generator that stalls when the AC kicks in.
How much does a whole-home generator cost in NJ?
The install is quoted, not billed as a service call. The number is driven by the size of the unit, the distance from the pad to the panel and to the gas supply, the transfer switch, the pad itself, permits and inspection. You get a written figure before anything is ordered.
Do I need natural gas or propane for a standby generator?
Either works. Natural gas is simpler where a line is already at the house, since there is nothing to refill. Propane means a tank on the property, which is the answer in areas without gas service, and it needs sizing so the tank can supply the generator’s demand as well as anything else it feeds. We check the gas supply capacity before specifying the unit.
Where does a standby generator have to be installed?
On a level pad outside, at the manufacturer’s required clearances from the house, windows, doors and vents, and clear of the gas meter. Local setback requirements and noise considerations also come into it. The location is often what decides the fuel and electrical run lengths, so we look at it before quoting rather than after.
Do I need a permit for a generator in New Jersey?
Yes, an electrical permit and usually a gas permit, filed with your township construction office, with an inspection on completion. We file both, meet the inspector and hand you the signed approval. Unpermitted generator work is a problem at closing and can affect the manufacturer warranty.
Serving Central New Jersey
Spartan Home Pros is a licensed, insured NJ electrical & HVAC contractor with our own crews — no subcontractors. We install and service whole-home generators across Hazlet, Holmdel, Matawan, Middletown and Monmouth County, plus Bridgewater and Somerset County. Call (732) 585-6560 for an upfront quote, or learn more about generator installation.