Fire Risk: Magnification of light

No doubt, one of the most petrifying things we can encounter is fire in the home. Having our family put in harms way can keep us up at night. This blog series give its readers an understanding of fire hazards that are encountered in the home, some that people may be aware of, while others not so much.

The unique properties of a magnifying glass have long been known to have the ability to create fire. As it were, all glass can start a fire if the sun rays pass through it, concentrating the light, directing onto flammable materials, causing ignition.

So, when you think of household items which pose a fire risk in your home, mirrors or windows may not come immediately to mind. Yes, leaving glass objects close to windowsills can cause fire. The images attached to this blog post have been donated as an excellent example of the risks caused.

The sun’s rays constantly bathe the earth with thermal energy. While this tends not to be strong enough to ignite paper, wood or other combustible substances, if the rays are focused, the flow of energy becomes concentrated enough to exceed the threshold for combustion.

Rays from direct sunlight (typical heat flux of 1 kW/m2) are not intense enough to ignite common fuels. If they are concentrated or focused by a transparent or concave object (such as a mirror or the bottom of some aerosol cans, they can reach 10 to 20 kW/m2 at the focal point of the light path. If a cellulosic fuel is located at or near that focal point, the fuel can be heated to its ignitable temperature and catch fire.

From the images attached, the householder left her property for a 50 minute run. When re-entering her home, she noticed that her dressing table was smoking. A make-up mirror positioned in such a way, reflected the afternoon sun, and began to burn the hairdryer nearby. Thankfully, this incident was discovered before fire could occur.

Thankfully, this incident occurred when the householder was nearby, as you would be surprised of the extent of fire damage that can be caused if such a fire had developed undetected. This mirror did have instructions highlighting the dangers of sunlight magnification.

So, if you are lucky enough to have a room which has great sunlight beaming through, carry out a risk assessment to make sure any glass objects cannot re-focus the sunlight, causing a fire. Be aware of free-standing magnifying mirrors, glass ornaments, magnifying glass, paperweights or certain aerosol cans, that could pose a potential fire risk in your home.

Fires can and do happen in the home, and as I have highlighted here, can occur due to uncommon methods. Be safe and prevent the chances of such fires occurring. Fit smoke alarms on each level of your home – it’s the simplest step you can take to cut the risk of dying in fire.

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