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Case 1

Fire caused by a magnifying glass focussing sunlight on to a bed

How this fire happened

The fire occurred on a sunny winter’s day in a resident’s second floor bedroom of a care home.

The elderly resident was not in the room at the time of the fire. The alarm was raised by the automatic fire alarm system fitted in the premises and the closed bedroom door contained the fire damage to the one room.


The fire was extinguished by fire crews.

In this instance there were three magnifying glasses placed in a pot on the bedside table. It only requires one glass or plastic concave lens with the correct focal length to concentrate the sun’s rays on to combustible materials for ignition to take place.


The same results can be produced by shaving (convex) mirrors, spectacles, metal bowls, chrome reflectors, glass containers filled with liquid as will some decorative window glass such as Bull’s eye (bullion) and Flemish glass.

The Fire Research Station has estimated that 150-200 fires occur annually in the UK due to focused sunlight (Vytenis Babrauskas, Ignition Handbook 2003, FSP).

Safety message​

Every year, the Fire & Rescue Service attends a number of fires caused by the solar rays focussing through or onto a lens.

This cause is more common during the winter months – when the sun is low in the sky.

Care should be taken when placing magnifying glass, mirrors, spectacles or any other glass or plastic object capable of focussing the sun’s rays, in a position adjacent to windows (especially those that are south facing) and close to combustible materials such as upholstery, curtains, paper etc.

Consider putting such objects away or covering them with a cloth when not in use.

Get into the habit of closing internal doors, not only as part of a bedtime routine, but also when you leave your home unattended. Even a light internal door will help prevent smoke and heat from damaging rooms and contents remote from the source of a fire.

Remember to regularly test your smoke alarm.

Case 2

Fire caused by a magnifying glass setting fire to curtains

How this fire happened


This fire was caused by a magnifying glass that was left on a window sill, which caused the suns rays to focus onto adjacent curtains, which eventually caught fire and spread to an office desk and paperwork before involving the remaining contents in the room.

The fire occurred in a family house that was unoccupied at the time of the fire. The family had left the house earlier in the day and had not shut internal doors.

There was a working smoke alarm - however with no one in the home to hear the alarm, the fire grew to such a size that eventually, a neighbour living opposite noticed smoke coming through the roof and called the Fire & Rescue Service.

Because of the late call to the Fire & Rescue Service the fire had already caused substantial damage by direct burning to the room of origin and a room above.


Unfortunately with internal doors being left open there was also serious smoke damage to other rooms in the house that were unaffected by direct burning.

The effect it had


In January 2010 my partner and our four children went out on a bright and sunny Sunday morning. When we returned at 5pm we were astounded to find that our house had been devastatingly ruined by fire and smoke.

The fire had started at approximately midday and no less that five fire engines were called to the scene approximately two hours later by our neighbours. It was obvious to us immediately that all our contents had been written off and that we had lost everything.

Within a few days we were told by the fire investigation team that the fire had almost certainly been caused by a magnifying glass, which had been placed in a south-facing window.


The sun had been intense that day and very low in the sky and its rays had been strong enough to create a beam of light on our study curtains eventually setting them on fire.

The level of stress that we have had to tolerate in the weeks and months after the fire has been unbearable at times. Even now after ten months we are still living in rented accommodation whilst our house is being re-built.

I have had to attend numerous meetings with builders, surveyors and architects and of course, have had to purchase everything in order to set up home again.

When I think how our fire started it sickens me to think that it could have been prevented so easily.

Many of us think that this will never happen to us but unfortunately in our case it did. Since the fire I have talked to many people who have experienced a similar fate.

Magnifying glasses, crystals, paperweights, shaving mirrors and other glass objects can be extremely dangerous if they are penetrable by the sun.

None of these items will ever be left near a window in my house again!

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