A grandmother in Chevy Chase went from celebrating Christmas Day with loved ones, to escaping a fast-moving fire in her own home.

Firefighters said it was a working smoke detector that made that happen.

The Montgomery County Fire Department tweeted a photo of the smoke detector they pulled from the burning home. The date on the back shows March of 2013. That's less than 10-years-old, meaning it's compliant with a new Maryland law that's about to take effect.

It's pretty important.

“You can see how close my house is to that house just 15-feet away. If she hadn't have had a smoke detector, it hadn't woken her up, I doubt she would've survived and my house would be gone,” said her next door neighbor, Stephen Palley.

The house caught fire around 2 a.m. in the 3300 block of Cummings Lane in Chevy Chase, MD. The newer fire alarm woke the grandmother sleeping inside. She escaped and was able to call for help.

The Chevy Chase grandmother was later treated for smoke inhalation.

Palley says as-soon-as he got to work, “I sent an email to everyone telling them to make sure they check the batteries in their smoke detectors."

Awareness is important, but in Maryland you may need to replace the whole unit -- not just batteries.

Come January 1st, the Maryland's Smoke Alarm Law will require people replace those nine-volt battery smoke alarms with a 10-year-long-life battery unit.

You'll also have to replace any smoke alarm (hard-wired or battery operated) that's 10 or more years past the manufacturer's date. Manufacturer's dates are usually printed on the back of the unit. If you don't see one, fire officials say to replace it.

WUSA9 went to a local hardware store to pick up a fire alarm and when you look on the bottom you might see a 10-year-limited warrantee and think, “Great,” this is what you need.

It's actually not.

We're told in Maryland, you need the alarms that say 10-year-sealed lithium battery on their label.

What happens after January 1st if you have a home fire and your detectors aren't compliant with the new law?

We're told it could hit you hard when you go to make that insurance claim.

The hope is this law will save more lives.

For more information on the new law, click here>>