If the casing of a household appliance becomes electrically charged, stop using it immediately and have it inspected and repaired.
There are generally three reasons why the casing of a household appliance might become charged:
Insulation breakdown or severe damage between live parts and the casing: In this scenario, touching the casing results in a strong electric shock, often making it impossible to pull away voluntarily. This is extremely dangerous; the power supply must be cut off immediately, and a professional should perform repairs to prevent electric shock accidents.
Poor insulation performance: Touching the casing causes a tingling sensation in the hand, though one can still pull away. While the shock sensation is relatively weak, it still poses a safety risk. Again, stop using the appliance immediately, check its insulation, and replace any damaged insulation components if necessary.
Voltage to ground caused by the appliance's inherent stray capacitance and insulation resistance: Touching the metal casing causes a slight tingling sensation, which disappears when the hand presses firmly against the casing. Although the sensation is mild, it still warrants attention. This issue can be resolved by connecting the appliance casing to a reliable ground wire, allowing leakage current to flow safely into the earth.
To prevent appliance casings from becoming electrically charged, the following measures can be taken:
Grounding protection: Ensure the appliance casing is connected to a reliable ground wire. This is an effective preventive measure. Ground wires should be inspected and maintained regularly to ensure secure connections and no damage.
Maintain ventilation: Do not block the ventilation openings of household appliances. Vents play a crucial role in keeping the interior dry, preventing component corrosion due to moisture, and dissipating heat. Therefore, ensure vents remain unobstructed during use.
Proper appliance usage: Avoid turning appliances on or off by plugging and unplugging the power cord, as this can damage components. For appliances that require frequent starting-such as refrigerators-avoid frequent plugging and unplugging to minimize damage to the compressor.
Regular inspection and maintenance: Periodically inspect and maintain appliances to identify and address potential safety hazards promptly.
Examples include checking for gas leaks (LPG or natural gas) and inspecting internal components for oxidation. In summary, an electrically charged appliance casing poses a potential safety hazard; the appliance should be taken out of service immediately and inspected or repaired. Measures such as ensuring proper grounding, maintaining adequate ventilation, using appliances correctly, and conducting regular inspections and maintenance can effectively prevent this issue.