72-hour storm runbook

Updated October 6, 2026.

Type a running load. The button prints gasoline, propane volume, refuels, and engine hours for 24, 48, and 72 hours. The checklist under it is the pre-storm, during, and after list. Print both.

Running watts (sequenced, not naive)

Hours per day the set will run

Onboard tank (gal)

House / pad name

Oil schedule

Hour meter at the start of the outage

Before the storm

Pick the outdoor spot now. CPSC says never use a portable generator inside a home, garage, basement, crawlspace, shed, or other enclosed area, even if doors or windows are open. Operate it outdoors only, at least 20 feet from homes and buildings, exhaust directed away from windows, doors, and vents. Carbon monoxide is colorless and odorless and can kill within minutes.
OSHA says give the generator 3 to 4 feet of clear space on all sides and above it so it can ventilate, and do not place it where doors, windows, or vents could let CO into occupied rooms. That 3 to 4 feet is clearance around the machine. It is not a shorter substitute for CPSC’s 20 feet.
Ready.gov says install carbon monoxide detectors with battery backup on every level. Generators and fuel stay outdoors, at least 20 feet from windows, doors, and attached garages. Use heavy-duty extension cords. Keep the generator dry. Let it cool before refueling, because fuel spilled on hot engine parts can ignite.
FEMA says never plug a generator into a wall outlet or the main electrical panel. OSHA says never attach a generator to a structure’s electrical system unless a qualified electrician installs it with a transfer switch. Permanent installation takes a licensed electrician and a permit where local code requires one. A cord into a dryer outlet is a backfeed, not a plan.
Ready.gov’s food list: keep freezers and refrigerators closed. A refrigerator keeps food cold for about four hours. A full freezer keeps its temperature for about 48 hours. Use a thermometer. Throw food out at 40°F or higher. Have nonperishable food and water on hand. The longer first-hour sequence is on how to use a generator when the power goes out.
Fill fuel before the station is on generator power itself. The table from the button is this page’s gasoline rule, not a manufacturer’s tank test. More placement wording is on how to run a generator safely.

During the outage

Put the generator in the outdoor spot you already picked. Rain is not an exception to CPSC’s ban on garage use, including a garage with the door open.
Ready.gov: keep the refrigerator and freezer closed. Turn off or disconnect appliances and electronics so a surge when utility power returns does not damage them. Do not heat the house with a gas stove or oven.
Plug appliances with heavy-duty cords, outdoors. Do not backfeed the panel. If a transfer switch is already installed, use it the way the electrician left it. The card’s “let it settle 30 seconds” line is a step in this page’s script, not a time from CPSC, Ready.gov, FEMA, or OSHA.
Start one motor, then the next. The lanes for that order are on the load sequencer.

After

Ready.gov: when in doubt, throw it out. Throw away food that has been at 40°F or higher for two hours or more, or that has an unusual odor, color, or texture.
Ready.gov: if the power is out for more than a day, discard refrigerated medicine unless the drug’s label says otherwise. Ask a doctor or pharmacist for a new supply.
The Honda EU2200i owner’s manual says to let the engine and exhaust cool before touching them, and to operate outside, away from open windows or doors, because of carbon monoxide. Do not run the set indoors to dry it.

What the fuel button is doing

Use this after the watt class is chosen. The sequencer or the home calculator is the watt step. This form takes running watts, hours per day, and onboard tank gallons.

GS.galPerHour in assets/lab.js sets gasoline gallons per hour = running watts ÷ 7,000. Propane gallons per hour = that gasoline rate ÷ 0.75. For a window of 24, 48, or 72 hours, gallons = gallons per hour × hours per day × (window ÷ 24). Refuels = the gasoline gallons divided by the tank, rounded up. Engine hours printed on the card = hours per day × 3, which is the 72-hour window only.

The ÷ 7,000 rule is this site’s portable gasoline rule of thumb, applied here to the running watts you type. The home calculator applies the same 7,000 to its recommended watts instead. EIA lists 120,214 Btu per gallon of motor gasoline and 91,452 Btu per gallon of propane. 120,214 / 91,452 is about 1.31, so the same heat needs about 31% more propane volume. The script’s ÷ 0.75 makes propane volume 1.33 times the gasoline gallons. That is the script, not EIA’s ratio. The home calculator’s 1.37 factor, applied to recommended watts, is on how much propane a generator uses.

The oil line follows the manual you pick. The menu opens on the Honda EU2200i owner’s manual. Its quick reference says to change the engine oil at the first 20 hours, then follow the maintenance schedule. On that schedule the engine-oil “Change” marks are the first month or 20 hours, and every 6 months or 100 hours, whichever comes first. The every-3-months-or-50-hours column on that page is not an engine-oil change. Generac’s GP6500/GP8000E manual says to change oil every 100 hours or every year, and the footnote says to change oil after the first 30 hours, then every season. This card reads that season as the yearly half of the same row. A separate footnote says to change the oil and the oil filter every month under heavy load or in high temperatures. The card does not count that monthly footnote. A 72-hour window is shorter than one month, so the card counts the hour column only, from the hour meter you type (the box opens at 0). Later changes are every 100 hours after that first hour-column change.

The form opens at 16 hours per day. That is a typed default, not an agency rule. Ready.gov’s four closed-fridge hours are a reason some houses do not run a set all night. Medical equipment is a reason to type 24. Sixteen is not a Wisconsin requirement.

Worked clicks

Default inputs, which are what the form shows before you edit them: 2,210 running watts, 16 hours per day, 4 gallon tank. 2,210 is the always-on running sum stored on the sequencer’s well-ranch list (150 + 200 + 1,000 + 700 + 160). The 700 W furnace fan matches Honda’s 1/3 hp row. The 150 W fridge running figure sits inside Honda’s 132–192 W band. Honda’s start for that fridge row is 1,200 W, not the 600 W stored on the ranch list, and the well and the 160 W lights are not on that Honda chart. The fuel math does not use the starting watts.

Gasoline gal/h = 2,210 / 7,000 = 0.316. Propane gal/h = 0.316 / 0.75 = 0.421.
24-hour window: 5.1 gal gasoline, 6.7 gal propane, 2 refuels of the 4 gallon tank. 48-hour window: 10.1, 13.5, and 3. 72-hour window: 15.2, 20.2, and 4.
Engine hours on the card: 16 × 3 = 48. Hour meter 0. Honda EU2200i is the selected schedule. The card counts 1 oil change, at hour 20. The next hour mark, 120, is outside the window. Six months do not pass, so the calendar half of Honda’s schedule adds nothing here.

Second click: same 2,210 W and 4 gallon tank, hours per day set to 24, Honda still selected, meter still 0. Gasoline becomes 7.6 / 15.2 / 22.7 gallons across 24 / 48 / 72 hours. Propane becomes 10.1 / 20.2 / 30.3. Refuels are 2, 4, and 6. Engine hours in the 72-hour window are 72. That is still 1 oil change, at hour 20. Hour 120 is still outside.

Third click: switch the oil schedule to Generac GP6500 / GP8000E, set hours per day back to 16, and leave the meter at 0. The card counts 1 oil change, at hour 30. The next hour mark is 130. At 24 hours per day the engine hours are 72, which is still that one change at hour 30.

Limits and a common mistake

Typing the home calculator’s recommended watts into this running-watts box overstates the cans. The food-truck page’s recommendation is 3,500 W from a 1,792 W running total. This script would treat 3,500 as running watts: 3,500 / 7,000 = 0.5 gal/h, and 0.5 × 16 h/day × 3 days = 24.0 gallons of gasoline for 72 hours. Typing the 1,792 W running total instead is 1,792 / 7,000 × 16 × 3 = 12.3 gallons. The button cannot tell those two inputs apart.

The gallons are not a Generac or Honda fuel test. Generac’s GP6500/GP8000E manual prints 11.5 hours at 50% load on a 7.9 gallon tank for that engine section. That is a test of that machine. It is not 2,210 ÷ 7,000. How that 11.5-hour tank sits against the first oil change is on how long a generator can run.

Compiled with AI assistance from the sources below. Spot an error? Email [email protected].