Don't even THINK about lighting a candle inside the Osbourne house -- because Sharon Osbourne tells TMZ, she's completely banned open flames from her home ... after an unattended candle nearly burned the place down last month.
TMZ broke the story ... Sharon forgot to put out the candle before going to sleep one night ... and the fire spread.
Thanks to the BHFD, the damage was minimal -- but on her way out of a Grammy party last night, the former "America's Got Talent" judge tells us ... she's done playing with fire.
"No more candles," she said. "Only in church!"