Electrical appliances are found in most households today. Whether at home or in the workplace, they are part of our lives, often taken for granted.
Many of these appliances represent serious potential hazards to children and adults alike. Electricity cannot be heard, seen, or smelt. It can, however, be felt. Faulty appliances can cause overheating and catch fire. It's crucial to be aware of the risks of using electrical appliances.
Electric shock
Electric shocks can happen as a consequence of heat, humidity, and moisture. Different environments can change how current travels through and over the surfaces of appliances. In warmer climates many cases of electrocution are due to fans that are badly earthed. People also get electrocuted because there are insufficient distances between live parts and touchable surfaces.
Fire and heat hazards
Many electrical fires are caused by dirty appliances. While breadcrumbs in a toaster do not transfer current, they can be a fire hazard. The same is true of a bathroom fan that has not been cleaned for many years.
Pollution can creep into insulated surfaces and ignite when exposed to electrical sparks. Sometimes only luck prevents the destruction of homes. For example, a recent case involved an unwelded joint in a dishwasher door switch. Over time this joint collected pollution, which, when the door was not closed completely, ignited, and melted the switch. Luckily the dishwasher itself didn't catch fire.
Careless use of appliances is another source of fires. Simply leaving a pot of cooking oil unattended on a switched-on stove may have dramatic consequences. Frequent sources of fires include electric blankets that are incorrectly installed, or electric room heaters that have been inadvertently covered.
Many electrical fires can be traced to faulty cords, outlets, and switches. Overloading extension cords or running several fixtures from a single outlet can all equally cause short circuits and fires.
Domestic appliances such as a dishwasher, dryer, or washing machine should always be plugged directly into an outlet. An overload in a dryer for instance can produce enough heat to melt or set fire to a lightweight extension cord.
Any switch or outlet that sparks or gives a shock when touched in the normal course of operation should be repaired or replaced immediately [and not used meanwhile].
Outlets should always be installed in the wall rather than in the floor, where they could get wet and then short circuit.
Burn hazards
Surface walls of many appliances can constitute serious burn hazards due to ineffective thermal insulation.
Low-quality products normally have less insulation material. Their surfaces can give serious burns, especially to babies and children. Hot oven doors are a typical example of a child hazard.
However, the burn effects of different materials can vary widely. At a similar surface temperature, wood will produce a different burn effect to that of glass, metal, or ceramics. This is related to the thermal conductivity and conductive capacity of a given material.
The severity of burns will also depend on the thickness of skin and its moisture content. Children usually have thin skin and a high level of moisture, which gives them a clear disadvantage. Other aspects resulting in more or less severe burns include the potential contamination of skin with grease and the duration and force with which the hot surface is touched.
IECEE tests reduce risks
The International Electrotechnical Commission (IEC) System of Conformity Assessment Schemes for Electrotechnical Equipment and Components (IECEE) tests all touchable surfaces of appliances, including handles, knobs, or grips. IECEE also tests those parts that are held for short periods of time, such as switches or the outer walls of a given appliance. The tests ensure that specified temperature limits are not exceeded.
Abnormal operation
Abnormal operation of an appliance can produce electric shocks, burns, or fire hazards. Conditions of abnormal use form part of IECEE Conformity Assessment (CA) tests that cover:
- temperature controls that malfunction
- moving parts, such as rotors, motors, or contacts of a relay that block
- failure of electronic components or software.
Sometimes, such abnormal operation requires a protective electronic circuit to mitigate the effects.
Dangerous parts
Not all hazards of operating electrical or electronic systems are obvious. The IECEE also looks at the accessibility of dangerous parts, such as rotors and blades. This is particularly important when small children, curious about everything, are keen to touch anything within reach.
The tests evaluate the crushing forces of doors and gates and the pinch points in playground equipment, for example. Many of these hazards can be reduced with sensors, such as infrared detectors, and pressure pads. The IECEE verifies the dimensions of these sensors, where they are placed, and how they function.
Faulty sensors can cause serious damage. A faulty sensor in a supermarket caused an elderly lady to break her hip. The supermarket doors failed to notice her arrival, closing on her.
The interaction of hazardous liquids and gases with electric systems, especially within non-conforming appliances, is the cause of many explosions every year. Take the example of a refrigerator, produced to lowest standards. When a small amount of flammable refrigerant, less than 50 grams, leaked onto a thermostat, it created an explosion that destroyed a whole kitchen.
And then there are the mechanical hazards linked to the design of an appliance. Children can get trapped in refrigerators or tumble dryers. The danger needs to be identified and intuitive escape mechanisms applied.
The IECEE also tests for hazardous substances, radiation, and toxicity that may harm users. Many hazardous substances are controlled by legislation, but low-quality products may consider such legislation. Appliances can produce toxic substances that will make them unsafe to operate in certain enclosed environments.
Many countries legislate for household appliances to protect the health and safety of their citizens. IEC international Standards, in conjunction with CA tests, can help them to do so.
Note: New Zealand is a member of the IECEE scheme. Household appliances which have been certified to the scheme are acceptable for sale in New Zealand providing they comply with any local variations to the relevant International Standard.
Summarised with permission from 'IEC E-tech' January/February 2010.
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