Generally, only appliances with metal casings require a ground wire; casings made of other materials do not.
Why do some appliance casings not require a ground wire?
Appliance casings are made of various materials. Some appliances feature casings made of non-conductive materials, such as plastic, and therefore do not require grounding. Conversely, appliances with metal casings require grounding because metal is conductive; without proper grounding, there is a risk of electric shock to the user.
Operating environments vary. Some appliances do not involve contact with metal during use-such as electric fans and hair dryers-and thus do not require grounding. Others, such as refrigerators and washing machines, may involve contact with metal parts during use and require grounding at an appropriate point to prevent electric shock hazards.
Which appliances do not require casing grounding?
Generally, only metal casings require a ground wire; casings made of other materials do not. Common examples of appliances that do not require casing grounding include:
Appliances with plastic casings, such as hair dryers and electric fans.
Appliances already equipped with a ground wire, such as air conditioners and washing machines. Since these are already connected to a ground wire, no additional grounding connection to the casing is required.
Low-voltage or safety-voltage appliances, such as mobile phones and computers.
Safety Precautions
Although the casings of these appliances do not require grounding, the following points should be observed during socket installation:
Fully understand the appliance's operating environment and relevant requirements, and wire accordingly.
Follow the guidelines in the user manual to connect the power cord correctly.
Regularly inspect the condition of the appliance and the socket to eliminate any unsafe usage conditions.