The most expensive generator mistake isn't buying too small. Call (201) 676-3099 or book a free estimate.
The most expensive generator mistake isn't buying too small. It's paying for a 26 kW unit when the house needed 18 — or buying the "whole-house" model and finding out during the first outage that the gas line can't feed it. Here's how we size a standby generator for a New Jersey home, with the real numbers.
Start with a list, not a kilowatt
Walk the house and write down what has to run when the power's out, and what would be nice. In a New Jersey winter, "has to run" is the furnace or boiler, the sump pump, the fridge and freezer, the well pump if you have one, a few lights and the Wi-Fi. In summer it's the same list plus the question that decides everything: do you want the central air on? Everything else — the dryer, the oven, the hot tub — goes on the nice-to-have list, and most of it stays there.
What common loads actually pull
Those are typical numbers, not your numbers. Your AC's nameplate and your well pump's horsepower are what we size from.
| Load | Running watts (approx.) | Worth knowing |
|---|---|---|
| Gas furnace or boiler (blower or circulator) | 600 – 1,200 | Must-run in winter; small load |
| Sump pump, 1/2 hp | 800 – 1,100 | Needs 2–3× that for a second to start |
| Refrigerator or freezer | 150 – 400 each | Starts at about 3× running |
| Well pump, 1 hp | 1,500 – 2,000 | Starts at 3×; common in Morris and Sussex |
| Lights, Wi-Fi, TV, phone chargers | 300 – 800 total | LEDs are almost free |
| Microwave | 1,000 – 1,500 | Short bursts |
| Electric water heater | 4,500 | The sneaky one — often left off the plan |
| Electric range or oven | 3,000 – 8,000 | Usually left off |
| Electric dryer | 5,000 – 6,000 | Usually left off |
| Central AC, 3 ton | 3,500 – 4,500 | Starts at 2–3× without a soft-start |
| Central AC, 5 ton | 5,500 – 7,000 | The reason units jump a size |
| Cold-climate heat pump | 3,000 – 6,000 | Strip heat stays off |
| Level 2 EV charger | 7,000 – 11,500 | Never on the generator plan |
The brackets, by what you want running
Installed, with the transfer switch, the gas line, the pad, permits and startup: a 14–18 kW essentials setup runs $9K – $12K in New Jersey in 2026, and a 22–26 kW whole-house unit runs $13K – $18K. A portable-generator inlet with a manual transfer switch or interlock is $900 – $2.2K if you'd rather start there.
| What has to run | Typical unit | Transfer switch |
|---|---|---|
| Essentials: heat, sump, fridge, well pump, lights, Wi-Fi | 10 – 14 kW | Essential-circuits sub-panel |
| Essentials plus one 3-ton central AC, with load management | 14 – 18 kW | Whole-house switch with a load-shed module |
| Most of a 200-amp house, one AC, gas appliances | 18 – 22 kW | 200-amp whole-house |
| Big house, two AC units, electric range or dryer, pool pump | 22 – 26 kW+ | 200-amp whole-house plus load modules |
| 5,000+ sq ft, two panels, everything on | 30 kW+ liquid-cooled | A different conversation |
Starting watts: why the AC decides the size
Motors need a jolt to start. A 3-ton air conditioner that runs on 4,000 watts can want 8,000 to 10,000 for the second its compressor kicks on. Add the sump pump and the fridge starting at the same moment and a 14 kW unit stalls. That's why the AC is the one line that jumps a house from an 18 to a 22.
There's a smarter way than a bigger engine. A load-management module in the transfer switch lets the AC start only when the generator has room, and a soft-start kit on the AC cuts the starting surge in half. Together they often let an 18 kW carry a house that a salesman would sell a 24 for. Two AC units get sequenced so they never start together.
The gas line nobody talks about
A 22 kW generator at full load burns roughly 250,000 to 300,000 BTU of natural gas an hour — more than your furnace and water heater put together. Tie it into a line that's already at capacity and the furnace starves on the coldest night of the outage. A lot of dealers rent a gas fitter for this and hope.
Our licensed master plumber sizes the whole house's gas load first, runs a new line at the right diameter, and pressure-tests it. If your meter can't deliver the flow, the utility upsizes it — we file that paperwork too. On propane, we size the tank for a few days of run time and set the regulator to the manufacturer's spec. Units make a bit less power on natural gas than on propane, so we size for the fuel you actually have.
Where it can sit
The unit has to be a set distance from windows, doors and fresh-air intakes, a set distance off the house, and clear of the property line — and some New Jersey towns want a zoning approval with a plot sketch before the building permit. Modern air-cooled units run about as loud as a central AC condenser during their weekly test, and we set that test for a civilized hour. On a tight Bergen County lot we'll show you where it can and can't legally go before you spend a dollar.
How we size it on the free visit
- The load list, room by room, written with you — must-run and nice-to-run in two columns
- Your panel and service size, and whether an essential-circuits sub-panel or a whole-house switch makes sense
- The AC nameplate, the well pump, the water heater — the loads that actually set the size
- The gas meter and the existing line, so the gas side is priced honestly from day one
- Where the unit can sit, and what your town will ask for
- Two or three options priced side by side: essentials, essentials plus AC with load management, and whole-house — so you pick with real numbers
Questions people ask next
Can a 22 kW generator run my whole house?
For most New Jersey homes on a 200-amp service with gas heat, gas cooking and one central AC — yes, with a load-management module so the big loads take turns. With two AC units, an electric range and an electric dryer all running at once, no. That's a 26 kW or a conversation about what stays off.
Will I need a bigger gas meter?
Often, yes, for anything over about 18 kW. A standard residential meter may not deliver enough flow for the generator plus the furnace and the water heater at the same time. The utility swaps the meter — usually at little or no cost — and we handle the request as part of the job.
Is a portable generator with an inlet good enough?
For a lot of families, yes. An outdoor inlet and a manual transfer switch or interlock — $900 – $2.2K installed — let you plug in one cord and flip one switch, with no extension cords through a window and no backfeeding the grid. The trade-off: someone has to be home, start it and keep fuel around. If you travel, have a finished basement or run medical equipment, go standby.
How long does the whole thing take?
Permits and zoning approval take two to four weeks in most towns. The install itself is one to two days: pad and unit, then gas, wiring and a real load test with the grid switched off. After a big storm, the units themselves go on backorder — order in a quiet month if you can.
Need generator installation near you?
If you searched “generator installation near me” anywhere in New Jersey, that's us. First Call Contracting is based in Paramus and sends its own licensed crew to all 21 counties — written price before work starts, no deposit, a real person on the phone 24/7.
Size it to your house, not the truck.
Free in-home load list and a fixed price for the unit, transfer switch, gas line and permits — from one crew with its own electricians and licensed plumbers.
Or call Alex direct: (201) 676-3099