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Preparedness

Power and lighting

Last reviewed: 10 November 2026

How a family of four in Charleston, Dorchester, or Berkeley County can size power banks and generators, with watt-hour and runtime examples and current carbon monoxide safety rules.

In the Lowcountry, a hurricane or severe thunderstorm can leave neighborhoods without electricity for hours or, after a major storm, for many days. Plan first for light and phone charging. Add larger power only if you can use it safely.

Light

  • Give each person a flashlight or, better, a headlamp, and keep one in the go-bag and one by the bed.
  • Store spare batteries in the sizes those lights actually take. Check them when you inspect the kit.
  • Chemical light sticks need no batteries and make no flame. They are useful for hallways and marking a path, not as a main light.
  • Electric lights are safer than candles or oil lamps. If you must use an open flame, never leave it unattended, keep it far from curtains, and have a fire extinguisher and a way out.

How to read capacity

Lithium-ion power banks are usually labeled in milliamp-hours (mAh) at a nominal cell voltage of 3.7 V. Convert to watt-hours so you can compare banks with loads:

Watt-hours (Wh) ≈ (mAh ÷ 1,000) × 3.7 V

Examples of rated energy, before losses:

Label on the bank Rated energy at 3.7 V
10,000 mAh 37 Wh
20,000 mAh 74 Wh
26,800 mAh about 99 Wh (near the usual 100 Wh airline limit for carry-on)

USB conversion, cable losses, and battery aging mean you will not get all of that energy out. In the worked examples below, usable energy is assumed to be 70% of the rated watt-hours for a USB power bank, and 85% inverter efficiency for a power station or generator supplying AC. Your devices will differ. Use the nameplate watts on each device when you can; the load table is illustrative.

Typical loads (illustrative — check the nameplate)

Device Typical running power Notes
Phone charger, while charging 5–15 W A modern phone battery is often about 12–16 Wh (for example, 4,000 mAh × 3.7 V ≈ 14.8 Wh)
LED bulb or lantern 5–12 W
USB fan 5–15 W A household box fan is often much higher, on the order of 40–80 W
Wi-Fi router or modem 10–20 W
CPAP Often about 30–60 W without a humidifier; higher with heated humidification Use the device label and talk to the clinician about an outage plan
Refrigerator Often 100–200 W while the compressor runs Cycles on and off; starting (surge) watts are often several times the running watts, commonly in the 600–1,200 W range
Chest freezer Often 100–200 W running, with a similar high surge A full freezer stays cold longer; see Food

Worked runtime examples

Example A — a 20,000 mAh power bank (74 Wh rated).
Assume 70% is usable: 74 × 0.70 ≈ 52 Wh.

  • Phones: if a full charge draws about 17 Wh (14.8 Wh battery ÷ 0.85 charging efficiency), the bank covers about 3 full charges.
  • A 5 W LED lantern: 52 ÷ 5 ≈ 10 hours.
  • A 10 W USB fan: 52 ÷ 10 ≈ 5 hours.
  • A 50 W CPAP or a refrigerator: this bank is not an appropriate supply. Those loads need a larger battery station or a generator.

For a household in which several people need a working phone, plan one bank in the 20,000 mAh (74 Wh) class per person, kept charged, rather than a single bank for the house.

Example B — a 500 Wh portable power station, used through an inverter.
Assume 85% inverter efficiency: 500 × 0.85 = 425 Wh usable on the AC side.

  • A 15 W router + 20 W of LED lights + 10 W of phone charging = 45 W. 425 ÷ 45 ≈ 9 hours.
  • A 50 W CPAP: 425 ÷ 50 ≈ 8.5 hours (about one night, with little margin).
  • A refrigerator that draws 150 W while running, but only one-third of the time, averages about 50 W. 425 ÷ 50 ≈ 8.5 hours — not a full day. Size a station in the thousands of watt-hours, or use a generator, if you need to hold a fridge or freezer through a multi-day outage.

Example C — generator sizing (running and surge watts).
Add the running watts of everything you will operate at once. Then add the starting watts of the largest motor that may start while the rest is already running. Choose a generator whose running-watt rating exceeds the simultaneous running total, and whose surge (starting) rating covers that largest start.

A sample list (replace with your nameplates): refrigerator 200 W running / 1,000 W surge; chest freezer 150 W / 800 W; lights 40 W; router 15 W; fan 50 W; CPAP 60 W. Simultaneous running total ≈ 515 W. If the freezer is already running and the refrigerator then starts, surge demand is about 1,000 + 150 + 40 + 15 + 50 + 60 ≈ 1,315 W. A unit rated around 2,000 W running and 2,500 W surge would cover this list with some margin — if, and only if, your actual nameplates are in this range and only one compressor starts at a time.

Fuel use varies widely. Read the manual and store only the fuel you can keep legally and safely. Fuel often runs out before the outage does.

Recharge power banks as part of ordinary life so they are not empty when the power fails. If someone depends on a powered medical device or on refrigerated medicine, talk to their clinician before storm season about backup power. Dominion Energy South Carolina offers a White Cross notification list for customers who use electrical medical equipment: call 800-251-7234 (Monday–Friday, 8:00 a.m.–5:00 p.m.) as described on the utility’s outage page. That list does not guarantee power; keep your own backup plan. A live Berkeley Electric Cooperative webpage for a comparable medical-outage notification program was not found on 10 November 2026 (a former /change-medical-program URL returned 404). Ask your own utility whether it offers a medical-equipment notification list, and still plan for backup power.

Unplug or switch off sensitive electronics when the power goes out, so a surge does not damage them when it returns. Leave one lamp switched on so you know when service is back.

Radios and medical backups

A battery or hand-crank radio that can receive NOAA Weather Radio is the most reliable way to hear watches and warnings if cell service is congested or down. See Communications. Keep spare batteries for the radio and for any medical device that takes them.

During an outage

  • Report the outage to your electric utility. Use the number on your bill if you are unsure which company serves you. In much of Charleston, Dorchester, and Berkeley Counties that is Dominion Energy South Carolina: use the Dominion Energy app or website, or call 888-333-4465. The same number is the official line for downed or sparking lines. Stay at least 30 feet from downed equipment, as the utility instructs. Many parts of the same three counties are served by Berkeley Electric Cooperative, whose own outage line (verified 10 November 2026) is 1-855-938-3615; you can also report outages in SmartHub. (Some older published lists, including the 2026 Charleston County Hurricane Guide and SCEMD’s outage list, still show 1-888-253-4232 for the cooperative.) Other official outage lines used in this region include Edisto Electric Cooperative at 1-800-433-3292 and Santee Cooper at 888-769-7688. A full table is on the local resources page.
  • If you smell natural gas or suspect a leak, Dominion Energy South Carolina’s official gas-leak number is 800-815-0083. Leave the area and call from a safe place. In a life-threatening emergency, call 911.
  • Keep refrigerator and freezer doors closed. Food timing is on the food page.
  • Check on neighbors who may need help, especially anyone who uses medical equipment or who may struggle in the heat.
  • If the house becomes dangerously hot or cold and a community cooling or warming center is open, consider going there.

Generators and carbon monoxide

A portable generator can run a refrigerator, some lights, and medical equipment. It can also kill people in minutes if it is used indoors or too close to the house. Carbon monoxide (CO) is colorless and odorless.

Ready.gov safety rules:

  • Operate generators outdoors only, at least 20 feet from windows, doors, and attached garages.
  • Never run a generator in a house, garage, basement, crawl space, or shed, even with the door open.
  • Keep the unit dry and out of floodwater. A wet generator, or wet cords, can cause shock.
  • Connect appliances with heavy-duty outdoor-rated extension cords, fully unwound. Do not back-feed a household panel with a homemade hookup; that can electrify utility lines and endanger line workers. Dominion Energy says not to connect a portable generator to a home’s electrical system. A licensed electrician can install a legal transfer switch if you want panel backup. Dorchester County’s hurricane preparedness page repeats the same rules: generators stay outside, at least 20 feet from windows and doors, protected from moisture, and never plugged into a wall outlet to power house wiring.
  • Let the engine cool before refueling. Fuel on a hot engine can ignite.
  • Store fuel in approved containers, away from living spaces and ignition sources, and in the amounts local fire rules allow.
  • Install carbon monoxide alarms with battery backup on every level of the home, and test them regularly.

The same outdoor-only rule applies to camp stoves, charcoal grills, and gasoline tools. Never use a gas oven or stovetop to heat the house.

If a CO alarm sounds, get everyone (including pets) into fresh air and call 911. Do not go back inside until emergency responders say it is safe.

Sources & further reading