Why Are Some Appliances Not Need Grounding?
Some equipment and power tools, such as vacuum cleaners and power drills, not need grounding. The reason for this is that they have plastic casings or are constructed in such a way that the live wire does not touch the casing.
As a result, even if the wires within fall lose, the shell cannot provide an electric shock to the user. This is called, double insulated devices.
What are double insulation devices?
Electric appliances have two layers of insulating materials, which separate the electrical parts of the appliance from any components on the outside that can be touched, called double isolation devices.
To protect people from electric shock, double insulation is introduced. For example, in most countries today, every power tool operated on mains voltage must be certified as meeting double insulation requirements.
Thermoplastic is used to insulate the motor’s armature core and stator core before copper is wound onto them.
The motor shaft is not welded directly to the rotor core but rather insulated using a resin filler. In the event of a failed insulation, this stops high voltage from the armature windings from leaking into the motor shaft.
In order to prevent electric shocks to the operator, the entire outer shell of the power tool must be made of plastic.
Most modern power tools don’t even require Protective Earth wires with all these arrangements. Hence, they are referred to as Double Insulation Compliant.
How Do You Know If An Appliance Is Double Insulates?
The double insulation protection of appliances indicated with the double square sign, indicates that the equipment is double insulated. You can find this sign on the device body. An appliance classified as Class II protection does not require a connection to electrical earth.
There is usually a plastic cover on a Class II appliance. In order to accurately identify it, you must look for the Class II appliance symbol. Hairdryers, DVD players, televisions, computers, and photocopiers are examples of Class II appliances.
Equipment with double insulation would normally be inspected as part of your ongoing PAT Testing regime. Still, it would likely not need to be inspected as a class I appliance subject to regular portable appliance testing.
Which Home Appliances is Double Insulated?
Hairdryers, DVD players, televisions, laptops, photocopiers, blenders, coffee makers, air blowers, drills, refrigerators, kettles, vacuum cleaners, and phone chargers are common examples of double-insulated household equipment.
This sort of appliance and tool is referred to as “double insulated.” They contain two layers of insulating materials between the appliance’s electrical components and any elements on the outside that you contact.
Why Are Some Appliances Double Insulated Instead Of Earthed?
Because double insulation prevents any possibility of the outer casing becoming live, it eliminates the need for an earth connection, thus protecting the user from an electric shock.
The double or reinforced insulation method involves adding supplementary insulation over the basic insulation or placing a single layer of reinforced insulation directly over the live parts to protect against electric shock.