Generators

Homeowner Summary

A backup generator keeps your home powered when the utility grid goes down. Whether from severe storms, ice events, grid overload, or equipment failure, power outages can last from hours to weeks. For homes that depend on electricity for well pumps, medical equipment, sump pumps, or climate control (especially in extreme heat or cold), a generator is not a luxury -- it is a safety system.

There are two main categories. Portable generators ($500-$3,000) are wheeled units that run on gasoline and connect to your home through extension cords or a manual transfer switch. They can power selected circuits but require manual setup, refueling, and cannot run during certain weather conditions safely. Standby generators ($5,000-$15,000 installed) are permanent installations that connect directly to your electrical panel through an automatic transfer switch (ATS). When power goes out, a standby generator detects the outage, starts automatically within seconds, and powers your home until utility power returns -- all without any action on your part.

Sizing is critical. An undersized generator will overload and shut down when too many loads start simultaneously. An oversized generator wastes fuel and money. A qualified electrician can perform a load calculation to determine the right size for your needs, whether you want to power essential circuits only or your entire home.

How It Works

All generators work on the same basic principle: an internal combustion engine spins an alternator to produce electricity. The engine burns fuel (gasoline, natural gas, propane, or diesel), and the alternator converts that mechanical energy into electrical energy at 120/240 volts.

Portable generators produce power through standard outlets on the unit itself. You can plug in extension cords directly or, much better, connect through a manual transfer switch that is wired to selected circuits in your panel. A transfer switch prevents backfeeding -- sending generator power back into utility lines, which can electrocute utility workers and damage equipment.

Standby generators are permanently wired to your home through an automatic transfer switch (ATS) installed next to or integrated into your electrical panel. The ATS continuously monitors utility power. When it detects an outage, it sends a start signal to the generator. Within 10-30 seconds, the generator is running and the ATS switches your home's circuits from utility power to generator power. When utility power returns and stabilizes (typically after a 5-minute delay to confirm stability), the ATS switches back and the generator shuts down and returns to standby mode.

Load management is a feature on many modern standby systems. Instead of sizing the generator for all loads running simultaneously, a load management panel (or smart ATS) prioritizes circuits and cycles loads on and off. This allows a smaller generator to effectively power a larger home by ensuring that the heaviest loads (HVAC, water heater, dryer) don't all run at the same time.

Maintenance Guide

DIY (Homeowner)

• Run the generator under load for 15-30 minutes monthly (standby generators typically do this automatically via weekly exercise cycle)
• Check oil level before and after each run (or monthly for standby units)
• Inspect for visible leaks, corrosion, or pest intrusion (mice love generator enclosures)
• Keep the area around a standby generator clear of debris, vegetation, and snow (minimum 3 feet clearance)
• Store gasoline for portable generators in approved containers, treated with stabilizer, and rotate every 6 months
• Check the battery on standby generators quarterly (12V starting battery similar to automotive)
• Test the automatic transfer switch by simulating an outage (turn off main breaker and verify generator starts and loads transfer)
• Keep a maintenance log with dates, hours, and services performed

Professional

• Oil and filter change every 100-200 hours of operation or annually (whichever comes first)
• Spark plug replacement annually (or per manufacturer schedule)
• Air filter replacement annually
• Coolant check and replacement (liquid-cooled units) per manufacturer schedule
• Battery load test and replacement every 3-4 years
• Transfer switch inspection: contact condition, timing, exercise cycle verification
• Load bank test every 2-3 years (runs generator at full rated load to verify capacity)
• Fuel system inspection: gas line connections (natural gas/propane), fuel quality, regulator function
• Exhaust system inspection for leaks or corrosion
• Firmware updates on smart generators and ATS units
• Full service per manufacturer maintenance schedule (typically every 200-500 hours)

Warning Signs

• Generator starts but won't accept load or shuts down under load (overloaded or governor issue)
• Unusual noises: knocking, rattling, or grinding
• Excessive vibration during operation
• Black or blue exhaust smoke (fuel or oil problem)
• Generator runs but produces no power (alternator or AVR failure)
• Automatic transfer switch fails to operate during a test
• Battery warning light on standby generator control panel
• Oil pressure or temperature warning lights
• Generator does not start during weekly exercise cycle
• Fuel consumption noticeably higher than normal
• Visible coolant or oil leaks
• Rust or corrosion on the enclosure or base

When to Replace vs Repair

Replace when:

• Generator is more than 20 years old and requiring frequent repairs
• Engine has more than 10,000 hours (air-cooled) or 15,000-20,000 hours (liquid-cooled)
• Major component failure (engine block, alternator winding) where repair exceeds 50% of replacement
• Current generator is undersized for added loads (EV charger, heat pump, addition)
• Technology upgrade desired (load management, smart monitoring, quieter operation)
• Fuel type change needed (gasoline to natural gas, for example)

Repair is appropriate when:

• Routine component failures: battery, voltage regulator, starter motor, control board
• Generator is under 15 years old and has low hours
• Transfer switch needs service but generator is sound
• Minor issues: fuel line leak, corroded connections, sensor failure

50% rule: If a single repair exceeds 50% of the cost of a new equivalent unit, replace. For generators under 10 years old, the threshold can be stretched to 60%.

Pro Detail

Specifications & Sizing

Load calculation method (simplified):

1. List all circuits/loads you want powered during an outage
2. Record running watts and starting watts for each load

| Load | Running Watts | Starting Watts | |---|---|---| | Central AC (3 ton) | 3,500 | 7,000 | | Central AC (5 ton) | 5,000 | 10,000 | | Refrigerator | 200 | 600 | | Sump pump (1/2 HP) | 800 | 1,300 | | Well pump (1 HP) | 1,500 | 3,000 | | Furnace blower | 800 | 1,600 | | Lights (20 LED bulbs) | 200 | 200 | | Garage door opener | 600 | 1,400 | | Electric water heater | 4,500 | 4,500 | | EV charger (Level 2, 32A) | 7,680 | 7,680 | | Electric range/oven | 5,000 | 5,000 |

3. Sum running watts for all loads: this is your minimum continuous rating
4. Add the highest single starting watts value: this is your minimum surge rating
5. Add 20% safety margin
6. With load management, you can reduce the sizing by 30-40% since heavy loads are cycled

Generator sizing guide:

| Size (kW) | Type | Powers | Best For | |---|---|---|---| | 3-5 kW | Portable | Essentials: fridge, lights, sump, phone charging | Short outages, apartments, budget option | | 7.5-10 kW | Portable or small standby | Essentials + well pump + furnace blower | Moderate loads, no AC | | 14-20 kW | Standby (air-cooled) | Most of home including AC | Typical single-family home | | 22-26 kW | Standby (air-cooled/liquid-cooled) | Whole house including large AC + EV | Larger homes, all-electric homes | | 30-48 kW | Standby (liquid-cooled) | Entire large home, all loads simultaneously | Estate homes, multiple HVAC systems |

Fuel type comparison:

| Fuel | Pros | Cons | BTU/unit | |---|---|---|---| | Natural gas (piped) | Unlimited supply, no storage, clean burning | Lower energy density, requires gas service | 1,030 BTU/cu ft | | Propane (LP) | Stores indefinitely, higher energy density than NG | Requires tank (250-1,000 gal), delivery needed | 91,500 BTU/gal | | Gasoline | Widely available, portable units | Goes stale (6 months), fire hazard, manual refueling | 120,000 BTU/gal | | Diesel | Highest energy density, efficient engines | Fuel gels in cold, louder, emissions | 139,000 BTU/gal | | Dual fuel (NG + LP) | Flexibility, redundancy | Higher equipment cost | Varies by fuel |

Common Failure Modes

| Failure | Cause | Frequency | |---|---|---| | Battery failure | Age, charging system fault, cold weather | Very common (leading cause of no-start) | | Stale fuel (portable) | Gasoline left untreated for months | Very common | | Control board failure | Power surges, moisture, age | Moderate | | AVR (automatic voltage regulator) failure | Surge, overload, age | Moderate | | Starter motor failure | Age, corrosion, excessive cranking | Less common | | Coolant leak (liquid-cooled) | Hose degradation, freeze damage, corrosion | Moderate for liquid-cooled units | | Transfer switch failure | Contact welding, coil failure, control board | Moderate | | Low oil shutdown | Consumption between services, leak | Common if maintenance is neglected | | Block heater failure | Element burnout, thermostat failure | Moderate in cold climates |

Diagnostic Procedures

1. No-start diagnosis: Check battery voltage (should be 12.6V or higher). Check oil level (low oil safety switch prevents start). Verify fuel supply (gas valve open, propane tank not empty). Check for error codes on the controller.
2. Starts but won't accept load: Check the ATS contacts and wiring. Verify voltage output at the generator (should be 240V +/- 5%). Check the AVR. Inspect the governor for proper frequency (60Hz +/- 0.5Hz).
3. Runs rough or surges: Check spark plugs. Inspect air filter. Verify fuel pressure (natural gas: 5-7" WC, propane: 11" WC at the regulator). Check governor linkage for binding.
4. Overload shutdown: Compare actual load to generator capacity. Check for motor starting surges. Verify load management system is functioning (if equipped).
5. Transfer switch testing: Simulate outage by opening main breaker. Time the sequence: detection (1-3 seconds), generator start (5-10 seconds), warm-up (10-15 seconds), transfer (total 10-30 seconds). Simulate utility return: verify retransfer delay (3-5 minutes), cool-down, and shutdown.
6. Annual load bank test: Connect a load bank and run at 75% and 100% of rated capacity for 2 hours each. Monitor voltage, frequency, oil pressure, and coolant temperature. This is the most thorough test of generator health.

Code & Compliance

• NEC 702: Optional standby systems (residential generators). Defines requirements for transfer equipment, capacity, and wiring.
• NEC 702.5: Transfer equipment must prevent interconnection of normal and alternate power sources (anti-backfeed protection).
• NEC 445.18: Generator must be grounded per NEC 250. Separately derived systems (most standby generators) require their own grounding electrode.
• NEC 700/701/702: Distinctions between emergency, legally required standby, and optional standby systems. Residential is typically Article 702.
• NFPA 37: Installation and use of stationary combustion engines and gas turbines. Covers clearances, ventilation, and fuel storage.
• Setback requirements: Typically 5 feet from openings (windows, doors, vents), 18 inches from the building, 5 feet from property lines. Local codes vary -- some require 10-foot setbacks.
• EPA/CARB emissions: Portable generators must meet EPA Phase 3 or CARB Tier 3 emissions standards. Some jurisdictions have additional restrictions.
• Permits: Standby generator installation requires electrical and often mechanical/building permits. Natural gas connections require a gas permit. Inspection is mandatory.
• HOA restrictions: Many HOAs have rules about generator placement, noise levels, and enclosures. Check before installation.
• Sound ordinances: Standby generators typically produce 60-70 dB at 23 feet. Local noise ordinances may restrict operating hours or require sound attenuation.

Cost Guide

| Service | Typical Cost | Key Factors | |---|---|---| | Portable generator (3-7.5 kW) | $500-$2,000 | Brand, wattage, inverter vs conventional | | Manual transfer switch + install | $500-$1,000 | Number of circuits, panel type | | Standby generator (14-20 kW) installed | $5,000-$10,000 | Brand, fuel type, site prep, permits | | Standby generator (22-26 kW) installed | $8,000-$13,000 | Larger unit, possibly liquid-cooled | | Standby generator (30-48 kW) installed | $12,000-$25,000 | Liquid-cooled, larger pad, more complex install | | Concrete pad | $500-$1,000 | Size, site preparation, gravel base | | Propane tank (500 gal) | $1,500-$3,000 | Above vs underground, local regulations | | Natural gas line extension | $500-$2,000 | Distance, trenching, gas meter upgrade | | Annual maintenance contract | $200-$500 | Includes oil change, filters, battery, inspection | | Major service (1,000-hour) | $500-$1,500 | Spark plugs, valves, coolant, full inspection | | Transfer switch replacement | $800-$2,000 | Manual vs automatic, number of circuits | | Control board replacement | $500-$1,500 | Parts + programming |

Costs reflect national averages as of 2026. Installation costs vary significantly based on site conditions, fuel availability, and local permit requirements. Lead times for standby generators can be 4-12 weeks.

Energy Impact

Generators consume fuel to produce electricity, so efficiency matters for operating cost. Modern standby generators achieve 15-30% fuel efficiency (converting fuel energy to electrical energy), with liquid-cooled units being more efficient under sustained loads.

Approximate fuel consumption at 50% load:

| Generator Size | Natural Gas | Propane | Gasoline | |---|---|---|---| | 14 kW | 200 cu ft/hr | 1.5 gal/hr | -- | | 20 kW | 260 cu ft/hr | 2.0 gal/hr | -- | | 22 kW | 290 cu ft/hr | 2.2 gal/hr | -- | | 7 kW portable | -- | -- | 0.7 gal/hr |

Cost to operate (approximate, at 50% load):

• Natural gas: $1.50-$3.00/hour (depending on local gas rates)
• Propane: $4.00-$7.00/hour
• Gasoline: $3.00-$5.00/hour

Variable-speed generators (inverter technology) reduce fuel consumption at light loads by slowing the engine, saving 20-40% compared to fixed-speed units during typical residential usage where loads fluctuate.

Load management systems also reduce fuel consumption by preventing all heavy loads from running simultaneously, allowing a smaller (more fuel-efficient) generator to serve the home.

Shipshape Integration

Monitoring capabilities:

• Generator runtime tracking via smart generator controllers (Generac Mobile Link, Kohler OnCue, Briggs IntelliGEN)
• Maintenance hour tracking with automatic service reminders based on runtime
• Transfer switch operation logging (number of transfers, last test date)
• Fuel level monitoring (propane tank gauge integration)
• Remote start/stop and status via manufacturer apps (integrated into Shipshape dashboard)

SAM alerts:

• Generator Maintenance Due: Triggered by runtime hours or calendar interval. Includes specific service items due (oil change, spark plugs, annual inspection).
• Generator Fault Detected: Real-time alert for any fault code reported by the generator controller. Includes fault code translation and recommended action.
• Transfer Switch Test Reminder: Monthly reminder to verify ATS operation. Tracks completion status.
• Generator Runtime Alert: Notification when generator has been running for extended periods (12+ hours), with fuel consumption estimate and remaining fuel calculation for propane systems.

Home Health Score impact:

• Backup power capability is a positive Resilience factor in the Home Health Score
• Generator maintenance status (current vs overdue) affects the score
• Automatic transfer switch (vs manual or no transfer) earns a higher score
• Load management capability earns additional credit
• Missing generator in areas with frequent outages triggers a recommendation

Dealer actions:

• Assess backup power needs during initial home evaluation (critical loads, outage history)
• Coordinate generator sizing with electrical panel capacity and planned future loads (EV, heat pump)
• Perform or coordinate semi-annual generator maintenance
• Test transfer switch during every home visit
• Monitor runtime remotely and schedule proactive maintenance
• Recommend generator upgrades when home loads increase (EV charger, pool equipment, HVAC upgrade)