Pacific Gas and Electric Co. could begin shutting off power Wednesday in 16 California counties due to windy, dry conditions that are expected to increase the risk of catastrophic wildfires. Parts of Alameda, Contra Costa, Marin, San Mateo and Santa Clara counties were initially going to be included in the planned blackout, but PG&E now says it won’t need to turn off power there. Portions of Napa, Solano and Sonoma counties are included in the current plan.

A red flag warning indicating dangerous fire conditions was issued, and the utility announced a power shut-off “watch” for 303,000 homes and businesses, which is equivalent to more than 900,000 people. Here’s what you need to know about the potential outages:

How long do power shut-offs last?

Power is restored in stages, location by location. PG&E has said it aims to restore power within 48 hours of getting an “all-clear,” meaning that the weather has calmed and the worst fire danger has passed.he company must inspect all lines for damage before restoring power.

Why did PG&E start doing preemptive power shut-offs?

PG&E first instituted the precautionary outages, which are intended to prevent its equipment from starting wildfires, in October 2018, a year after some of its power lines were blamed for the devastating Wine Country wildfires. CEO Bill Johnson told state regulators recently that his company is working to make forced power outages unnecessary, but the goal could take a decade to accomplish. On Nov. 18, he told state lawmakers that the scope of potential shut-offs could diminish by as much as a third next fall as PG&E improves its infrastructure.

How does PG&E decide whether to issue a shut-off?

PG&E considers whether red-flag fire danger warnings have been issued. Humidity levels must generally be below 20% and high winds above 25 mph, with gusts in excess of 45 mph. Officials also consider the amount of dry vegetation and use observations from PG&E field crews and meteorologists.

How should I prepare for a power outage?

Public safety and PG&E officials advise residents to prepare for life without electricity by:

• Keeping phones and other electronics charged while also having backup charging methods available.

• Building or replenishing emergency kits that include flashlights, spare batteries, a first-aid kit, emergency food and water, and cash.

• Learning how to manually open your garage door.

• Unplugging electrical appliances to avoid overloading circuits and preventing fire hazards when power is restored.

• Storing drinking water — 2 gallons per day per person and more for pets, as water delivery services could be affected by a shutdown.

Can solar panels spare me from a power shut-off?

People with solar systems are still connected to the PG&E power grid, so if PG&E cuts off the power for safety, their power gets shut off automatically. People who have a home battery paired with their solar system can avoid full outages.

Should I buy a generator?

Generators can be a helpful but expensive solution to a temporary problem. They can run anywhere from a couple of hundred dollars to as much as $14,000. Follow safety instructions, and don’t try to install your own generator if you aren’t an expert: the do-it-yourself dangers outweigh the savings benefit.

Why doesn’t PG&E have underground power lines?

Putting power lines underground is expensive — $3 million per mile, according to a 2017 estimate from PG&E, versus up to $800,000 for overhead lines. That’s just for smaller, lower-voltage distribution lines; long-distance transmission lines are even costlier. Underground lines would also be harder to fix in an earthquake. However, in May, PG&E said it would put lines underground in Paradise, the Butte County city destroyed by the 2018 Camp Fire.

It’s not windy in my area. Why is my power still cut?

A long-distance power line that delivers electricity to you may pass through a location where it’s very windy, or forecast to become windy, according to PG&E, which is turning off some of these high-voltage lines, known as transmission lines.

Will my cell phone still work?

Cell phone carriers told federal regulators that service should still work during shut-offs, but that isn’t always the case. Cell sites either have backup generators, which can last days, or batteries which can survive only a few hours. There are no federal or state requirements for backup power at cell sites.

What should I do with food in my refrigerator?

Meat, poultry, fish and eggs should always be stored in temperatures 40 degrees Fahrenheit or colder, and frozen goods should be 0 degrees or colder. Officials advise people to keep refrigerator and freezer doors closed as much as possible during outages. Refrigerators can safely store food — and keep items cold — for about four hours. Freezers can keep their temperature for about two days if unopened. Dry ice or blocks of regular ice can help store food.

How can I get updates if I’m not a PG&E account holder?

PG&E has an alert system that notifies non-account holders of power outages in a specific area. Company officials said they will try to alert people 48 hours, 24 hours and just before power outages. To sign up, go to pge.com/pspszipcodealerts.