Causes, Consequences and Prevention of Fires in Domestic Refrigeration Systems

This study was proposed to investigate and examine the causes, consequences and prevention of fires occurring in domestic refrigeration appliances. The aims were to analyse such incidents, examine their characteristics and understand the underlying ignition and fire spread mechanisms that have led to their occurrence and how they might be prevented. The reasons for the cause and spread of domestic refrigeration fires have been examined, using information obtained from the analysis of fire data sets available in Great Britain and on the basis of fire investigations carried out in London. Visits to refrigerator disposal sites and local authority amenity centres also provided information on changes to appliance construction techniques and component use over several decades. Analysis of the available data suggests that once ignition occurs, fires caused by fridge/freezers are more likely to exhibit a higher degree of fire spread and produce greater levels of damage than other types of white goods appliance (washing machine, dishwasher or tumble dryer). Nearly 80% of fires with fridge/freezers as the source of ignition, spread beyond the first item involved, whilst almost 40% spread beyond the room of origin. Fires involving fridge/freezers also displayed a far higher casualty rate per fire than was found for the other types of appliance. Based upon evidence obtained from fire investigations a number of common failure modes leading to ignition in domestic refrigeration fires have been identified: (i) starter relay failures; (ii) PTC switch failures; (iii) mechanical defrost switch failures; (iv) capacitor failures; (v) solenoid valve failures; (vi) cut-out switch failures in integrated appliances, and (vii) rodents. Specific fire escalation and spread mechanisms have also been identified: plastic drip trays, “twin-wall” backing materials and polyurethane foam insulation panels. There is also evidence to suggest that the severity of refrigeration fires in Great Britain is significantly higher than in the USA. Based upon information obtained from LFB fridge and freezer fire investigations, and a comparison between the design and construction of refrigeration appliances used in Great Britain and USA, a number of recommendations have been made which could be used to significantly reduce the risk of a serious fire e.g. avoiding the usage of plastics in appliance housings and in particular employing a metal/non-combustible covering at the back of fridge and freezer appliances and ensuring that insulating foam is separated from the spread of fire by fire resisting material.