Generator Installation Guide for Wisconsin Homeowners

The Quick Answer

Whole-house generator installation in Wisconsin requires permits, professional installation, and a transfer switch that prevents dangerous back-feeding into utility lines. Generators must be properly sized for your home's electrical load, installed on a level concrete pad with appropriate clearances, and connected to a reliable fuel source (natural gas or propane). Wisconsin's cold winters make generator sizing and fuel considerations particularly important.

Types of Home Generators

Portable Generators

What they are: Gasoline-powered units that can be moved and stored.

Power output: Typically 3,000–10,000 watts

Best for: Emergency backup for essential items only (refrigerator, lights, sump pump)

Limitations:

Requires manual setup during each outage
Must be operated outdoors (carbon monoxide risk)
Limited fuel storage and runtime
Cannot power whole house or hardwired systems
Requires extension cords to individual appliances

Wisconsin consideration: In severe winter weather, going outside to start and refuel a portable generator can be difficult or dangerous.

Standby (Whole-House) Generators

What they are: Permanently installed units that automatically start when power goes out.

Power output: Typically 10,000–48,000+ watts (10–48+ kW)

Best for: Homeowners who want seamless backup power without manual intervention

Advantages:

Automatic operation (starts within seconds of outage)
Can power entire house or selected circuits
Runs on natural gas or propane (no refueling during outages)
Permanent installation means it's always ready
Self-testing keeps the unit maintained

Wisconsin consideration: Automatic operation is valuable when outages occur during dangerous cold. You don't need to go outside or be home for backup power to engage.

Wisconsin-Specific Requirements

Permits and Inspections

Generator installation in Wisconsin typically requires permits covering:

Electrical permit: For the transfer switch and connections to your electrical system

Mechanical permit: For the generator unit itself (varies by municipality)

Gas permit: If connecting to natural gas or installing propane lines (usually separate from electrical)

Zoning considerations: Setback requirements from property lines, placement restrictions, noise ordinances

Permit requirements vary by municipality. Your installer will know what's required for your location.

Transfer Switch Requirement

Wisconsin, like all states, requires a transfer switch for standby generator installations. This is a safety-critical component.

What it does: Isolates your home's electrical system from the utility grid when the generator is running.

Why it's required: Without a transfer switch, electricity from your generator can "back-feed" into power lines, creating lethal hazards for utility workers repairing outages.

Types:

Automatic Transfer Switch (ATS): Senses outage, starts generator, switches power automatically
Manual Transfer Switch: Requires you to physically switch power sources

Standby generators always use automatic transfer switches. The generator starts and transfers power without any action required from you.

Fuel Source Considerations

Natural Gas:

Unlimited fuel supply (no tank to refill)
Requires gas line connection to your meter
Slightly lower BTU than propane (may need larger generator)
Not available in all areas

Propane (LP):

Requires tank installation and periodic delivery
Higher BTU value (more power per unit)
Available anywhere (good for rural properties)
Tank must be sized for expected runtime
During widespread emergencies, propane delivery may be delayed

Wisconsin winter consideration: Both fuel types work in cold weather, but propane pressure can drop in extreme cold. Proper tank sizing and regulator selection are important.

Generator Sizing Fundamentals

Proper sizing is critical. An undersized generator will overload; an oversized generator wastes fuel and money.

What Affects Sizing

1. What you want to power:

Essential circuits only? (Heat, refrigeration, sump pump, lights)
Whole house?
Specific high-demand items? (AC, well pump, electric range)

2. Starting vs. running watts:

Many appliances (especially motors) require 2–3x more power to start than to run
A well pump may run at 1,000 watts but need 3,000 watts to start
The generator must handle the highest starting load

3. Wisconsin heating considerations:

Gas furnace: Needs electricity for blower and controls (typically 500–2,500 watts depending on size)
Electric heat: Very high electrical demand (may not be practical to back up fully)
Heat pump: Moderate demand, but check starting watts

4. Common load examples:

Item	Running Watts	Starting Watts
Refrigerator	100–400	1,200–2,000
Gas Furnace Blower	500–2,500	1,500–5,000
Sump Pump (1/2 HP)	800–1,050	2,000–3,000
Well Pump (1/2 HP)	1,000	2,000–3,000
Central AC (3 ton)	3,500	4,500–7,000
Electric Water Heater	4,000–5,500	4,000–5,500
Electric Range	2,000–5,000	2,000–5,000

These are general estimates. Actual values depend on specific equipment.

General Sizing Guidelines

Home Size	Essential Circuits	Whole House (no AC)	Whole House (with AC)
Small (<1,500 sq ft)	10–14 kW	14–18 kW	18–22 kW
Medium (1,500–2,500 sq ft)	14–18 kW	18–22 kW	22–26 kW
Large (2,500–3,500 sq ft)	18–22 kW	22–30 kW	30–38 kW
Very Large (3,500+ sq ft)	22+ kW	30+ kW	38+ kW

These are rough guidelines. Actual sizing requires a load calculation based on your specific equipment and usage patterns.

Installation Requirements

Site Preparation

Generator pad:

Level concrete, composite, or gravel pad
Must support the generator's weight (typically 300–500+ lbs)
Sized appropriately for the unit with room for service access

Clearances:

Distance from windows, doors, and vents (varies by manufacturer and code)
Distance from combustible materials
Distance from property lines (check local zoning)
Access for maintenance and fuel delivery

Drainage: Area should drain away from the generator pad

Electrical Work

Transfer switch installation:

Located at or near the main electrical panel
Wired to either the whole panel or selected circuits (depending on system type)
Includes load management if applicable

Generator connection:

Properly sized conductors from generator to transfer switch
Weather-resistant conduit for outdoor runs
Disconnect means as required by code

Grounding:

Generator grounding per NEC requirements
May need to coordinate with existing home grounding system

Fuel Connection

Natural gas:

Connection to existing gas meter (may require meter upgrade)
Properly sized gas line for generator BTU requirements
Shutoff valve at generator

Propane:

Tank sizing (typically 250–500+ gallon for whole-house generator)
Buried or above-ground tank (regulations vary)
Line sizing and pressure regulation
Setback requirements for tank placement

Maintenance Requirements

Standby generators require regular maintenance to ensure reliability:

Weekly (Automatic)

Self-test cycle (most generators run briefly each week automatically)

Annual (Professional Service)

Oil and filter change
Air filter inspection/replacement
Spark plug inspection/replacement
Battery testing
Transfer switch testing
Load bank testing (verifies full-load operation)
General inspection of all components

As Needed

Coolant service (liquid-cooled units)
Fuel system service
Software updates (if applicable)

Wisconsin consideration: Schedule annual maintenance before winter storm season, not during it.

Frequently Asked Questions

Q: How long can a standby generator run continuously?

Natural gas generators can run indefinitely as long as gas service is maintained. Propane generators are limited by tank size—a 500-gallon tank might provide 5–7 days of continuous operation depending on load and generator size. Both types need periodic rest and maintenance checks during extended outages.

Q: How loud are standby generators?

Modern standby generators typically operate at 60–70 decibels at 23 feet—roughly equivalent to a normal conversation or air conditioner. Older or larger units may be louder. Some municipalities have noise ordinances affecting generator placement.

Q: Do I need to be home for the generator to work?

No. Standby generators with automatic transfer switches start and switch power without any human intervention. If power goes out while you're at work or on vacation, the generator handles everything automatically.

Q: What happens when utility power comes back?

The automatic transfer switch senses that utility power has returned and is stable (typically waits a few minutes to confirm), then transfers your home back to utility power and shuts down the generator.

Q: Will a generator damage my electronics?

Quality standby generators produce clean, stable power similar to utility electricity. They typically include voltage regulation and are safe for sensitive electronics. Portable generators have more variable power quality, which is one reason standby units are preferred for whole-house backup.

Q: How much does it cost to run a generator?

Fuel consumption depends on generator size and load. A 20 kW generator at half load might use 1–2 gallons of propane or 150–250 cubic feet of natural gas per hour. During extended outages, fuel costs can be significant. This is another reason proper sizing matters—an oversized generator burns more fuel than necessary.

Why Generator Installation Isn't Simple

Generator installation involves multiple trades and requirements:

Electrical: Transfer switch, panel connections, grounding
Mechanical: Generator placement, pad construction
Plumbing/Gas: Fuel line installation and connections
Permits: Electrical, mechanical, gas, possibly zoning
Utility coordination: May need to notify electric and gas utilities
Sizing calculations: Requires understanding of your specific loads

This complexity is why reputable installers visit your home before providing a scope—there are too many variables to assess remotely.

Next Step

Generator installation starts with understanding your needs and evaluating your home's electrical and fuel capabilities.

[Schedule a Generator Consultation →]

We'll discuss your backup power goals, assess your home's requirements, and explain what installation involves for your specific situation.