An open flame is any fire that burns exposed to the surrounding air, without being enclosed behind glass, a sealed chamber, or other barrier. Candles, lighters, matches, gas stovetop burners, Bunsen burners, welding torches, and oil lamps all qualify. The key distinction is that the combustion is visible, uncontained, and in direct contact with the atmosphere, meaning it can ignite nearby flammable materials, vapors, or gases.
Common Examples of Open Flames
The most familiar open flame is a candle, but the category is broader than most people realize. All of the following produce an exposed flame and are classified the same way in fire codes and safety regulations:
- Candles, oil lamps, and lanterns
- Matches and cigarette lighters
- Gas stovetop burners and pilot lights
- Bunsen burners and butane burners
- Propane torches and welding torches
- Fire pits and tiki torches
- Smoking materials (lit cigarettes, cigars, pipes)
Pilot lights deserve special attention because they’re easy to forget. A gas water heater or older furnace with a continuously burning pilot light counts as an open flame, which is why you should never store gasoline, paint thinner, or other flammable liquids near one.
What Makes a Flame “Open”
Two conditions define an open flame. First, combustion happens in direct contact with the surrounding atmosphere, drawing on an essentially unlimited oxygen supply from the air. Second, the fire is not enclosed by a physical barrier that would contain its heat and prevent contact with nearby materials. A NASA combustion report draws the distinction clearly: in an open environment, the fire is supported by atmospheric oxygen while heat and combustion products dissipate freely into the surroundings, rather than being contained in a sealed system.
This is why a sealed gas fireplace with a glass front is generally not considered an open flame, while the same fireplace with the glass removed would be. The flame itself may look similar, but the enclosure changes the safety classification.
What Doesn’t Count as an Open Flame
Electric heating elements, toasters, space heaters with glowing coils, heat guns, and electric stoves are not open flames. They can absolutely start fires, but they produce heat through electrical resistance rather than combustion, so no actual flame exists. Open-coil electric heaters do pose ignition risks because their energized elements reach high temperatures and are exposed to the air, but they fall into a separate safety category from open flames.
Microwave ovens, induction cooktops, and enclosed gas appliances with sealed combustion chambers also fall outside the definition. The practical takeaway: “no open flame” rules typically don’t apply to these devices, though they may be restricted for other safety reasons.
Why “No Open Flame” Rules Exist
Open flames are one of the most common ignition sources in both residential and industrial fires. Federal workplace safety regulations list open flames alongside sparks, hot surfaces, static electricity, and electrical arcs as primary ignition hazards. The reason open flames get singled out so often is that they combine high temperature, direct atmospheric exposure, and the ability to ignite flammable vapors that may have traveled some distance from their source.
OSHA regulations prohibit open flames entirely in flammable liquid storage areas. For highly flammable liquids, the rule is stricter: they cannot be used anywhere along the possible path of vapor travel if an open flame is present. Flammable vapors are heavier than air and can flow along floors and through doorways, meaning a flame across the room, or even in an adjacent space, can ignite them.
Open Flame Rules in Apartments and Dorms
Most university housing and many apartment complexes ban all open flame devices. At Illinois State University, for example, the policy specifically names candles, torches, butane burners, lanterns, oil lamps, and “any other flame producing devices” as prohibited. Propane-fueled flames are banned from all university buildings entirely.
Apartment lease restrictions typically mirror this language. If your lease includes a “no open flame” clause, it almost certainly covers candles (even decorative ones you intend to light), incense that burns with a visible flame, and any portable gas-fueled device. Battery-operated LED candles and electric wax warmers are the standard workarounds, since they produce no flame at all.
Safe Distances From Open Flames
When open flames are permitted, spacing matters. Laboratory safety guidelines require that flammable liquids stay at least one foot from any flame source, and combustible materials like paper, cardboard, and fabric must remain at least two feet away. The flame should never be positioned under shelving, cabinets, or overhanging equipment.
Industrial standards are more conservative. OSHA requires a minimum of 5 feet between flammable liquid connections and any building opening, and 10 feet or more between buildings and stored flammable liquids when quantities exceed about 1,100 gallons. Fuel loading facilities must maintain 25 feet of separation from buildings when handling the most flammable liquid categories. These distances account for vapor travel, radiant heat, and the potential for spills to spread fire rapidly.
For everyday situations at home, keeping candles at least two feet from curtains, bedding, papers, and anything else that burns is a reasonable minimum. Place them on stable, non-flammable surfaces, and never leave them unattended. A burning candle on a nightstand next to a curtain is one of the most common residential fire scenarios, and it’s entirely preventable with a little distance.