A candle is a controlled fire sitting on your coffee table. Most people never think about it that way, but firefighters do, because candles cause roughly 7,000 home fires a year in the United States and a large share of them start in bedrooms.
Candle wax is combustible, and it is the fuel that keeps the candle burning. The wick is just a delivery system. Heat from the flame melts the wax, the liquid wax travels up the wick by capillary action, and the flame vaporizes it. It is the wax vapor that burns. Paraffin wax has a flash point around 390°F to 480°F depending on the blend, and soy and beeswax are in a similar range.
Why a Candle Doesn't Just Burst Into Flames
If you hold a match to a solid block of wax, nothing much happens. The wax melts and maybe smokes, but it won't sustain a flame, because solid wax can't get hot enough to vaporize fast enough. The wick solves that by pulling a tiny amount of liquid wax into a small, very hot zone. That is the whole trick behind a candle, and it is also why a candle is safe until something changes the balance.
How Candles Start House Fires
- Something combustible gets too close. Curtains, bedding, paper, decorations. This is the majority of candle fires. The flame doesn't need to touch; radiant heat from a few inches away can ignite thin fabric.
- The candle burns down into the holder. A candle in a glass jar burned to the bottom can crack the glass or heat the surface underneath enough to ignite it.
- A pool of melted wax ignites. If a candle is left burning for hours, the wax pool gets deep and hot. If the wick falls over into it or a second flame source touches it, the entire surface of the pool can catch. A wax pool fire looks like a small grease fire and behaves like one.
- Falling asleep. Bedroom candles plus sleep is the deadliest combination in the data.
- Pets and kids. Knocked-over candles are common, and a tipped candle spills burning liquid wax.
If Melted Wax Catches Fire
Treat it like a grease fire. Do not use water; water will spatter the burning wax. Smother it with a lid or a baking sheet, or use baking soda on a small one. A fire extinguisher works if it has spread. If the fire has reached anything beyond the candle itself, get out and call 911.
How to Burn Candles Safely
- Keep at least 12 inches of clearance from anything that can burn.
- Trim the wick to a quarter inch before each use. Long wicks make tall, unstable flames.
- Don't burn a candle for more than four hours at a time, and stop when half an inch of wax remains.
- Use a sturdy, heat-resistant holder on a stable surface.
- Never leave a burning candle in a room you aren't in. Blow it out when you leave, every time.
- Consider flameless LED candles in bedrooms and anywhere kids or pets spend time.
Candles are fine. Unattended candles are how we meet people on the worst night of their lives. For related reading, see whether petroleum jelly is flammable and our fire safety tips from a firefighter.
