Such appliance are designed so that there are two levels of insulating material between the electrical parts of the appliance and any parts on the outside that can be touched. These two layers are normally the insulating plastic case and the insulated cable carrying the live and neutral wires.
Double Insulation is the additional insulation barrier added to an electrical device to protect the user from electrical shock in the event the fundamental functional electrical insulation system should ever fail.
Double or reinforced insulation is another method of protection against electric shock, consisting of an extra layer of supplementary insulation over the basic insulation, or a single layer of special reinforced insulation directly over the live parts.
Double layer is generally used in higher voltage cables, such as power transmission in generators, transformers and cables, while single layer is often used in control cables, communication cables, automotive cables and some low voltage power cables.
In the United Kingdom, a double insulated appliance must be labelled Class II, double insulated, or bear the double insulation symbol (a square inside another square). An example of a double insulated electrical appliance could be an electric drill or a desk fan.
In Europe, a double insulated appliance must be labelled Class II or double insulated or bear the double insulation symbol: ⧈ (a square inside another square).
Romex Cables
NM and NMC conductors are composed of two or more insulated conductors contained in a non-metallic sheath.
However, double-insulated tools do not require the equipment grounding conductor tests, since they are not required to be grounded. The exposure to ground-fault hazards exists when any electric tool is being used even on a grounded circuit.
Basic insulation - provides the user a single and simple protection from electric shock. Supplementary insulation – like basic insulation, must withstand 1.5KVAC (2.1KVDC). Double insulation – the use of basic and supplementary isolation in conjunction to provide redundancy.
On the other hand, Class II devices are double-insulated appliances. These are manufactured with non-conductive enclosures, such as plastic, and are usually marked with a double-boxed symbol. Class II devices do not require an earthing conductor and should not be earthed.
6181-XY Double Insulated PVC Mains Cable. These cables are designed for fixed installations in industrial settings and buildings, excluding direct burial. They are double-insulated single-core power cables intended for installation in walls, boards, channels, or embedded in plaster.
#1 insulated wire is made from uncoated, unalloyed copper, and it's generally worth more than #2 wire because of its purity. #2 insulated wire has a lower copper content and often is used in telecommunications wiring and home electronics.
Yes, by enhancing the energy efficiency of a building, double insulation reduces the consumption of energy resources and thus contributes to sustainable construction. It can be an integral part of green building practices.
Designed For Tough Building Applications
Single core double insulated wires are designed to carry substantial amounts of power between building zones. If there's a pair of power linkages in a structure that requires a mechanically tough hookup line, then this is the cabling that's installed.
You should install two layers of insulation in your attic; wood joists must be covered to allow the air to move. The first layer will sit between the joists, and the second layer will run perpendicular over the joists. The first layer should have the facing against the drywall to act as a vapor barrier.
This marking consists of the double insulation symbol (a square within a square) and the words "double insulation" of the equivalent words "double-insulated."
Appliances encased in an insulating plastic case or body, such as hair dryers, mobile phone chargers and hand whisks do not need an Earth wire. Such appliance are designed so that there are two levels of insulating material between the electrical parts of the appliance and any parts on the outside that can be touched.
If your house has two prong outlets with metal boxes, it is possible you can ground your outlets without overhauling the wiring. To find out whether the metal housing is grounded, purchase a circuit tester. Insert one of the tester's prongs into the hot slot (the shorter slot in the outlet).
Double Insulated Lighting Products
From the outside a double insulated light looks exactly the same as a normally earthed light. You cannot tell the difference in any way from just looking at a product. Once you delve inside the products however it becomes quite clear what the differences are.
Noting that Romex is the name of a popular brand of Non Metallic cable, of the type specified in the NEC (US National Electrical Code) as type NM. (Like “Kleenex” is a brand of facial tissue.) Romex is not permitted anywhere that it is exposed to risk of damage, to water (dampness), and/or to sunlight.
14-gauge is used for lamps, light fixtures, and lighting circuits with 15 amps. 16-gauge is best for extension cords supporting 13 amps. 12-gauge is ideal for use in the bathroom, kitchen, outdoor receptacles, and 120-volt AC's supporting 20 amps.
Many of the newer small electrical appliances and tools do not have a the third grounding prong on the plug. Typical examples are blenders, coffee makers, blow dryers, drills, and other power tools. Appliances and tools of this type are called "double insulated".
The plug contains three wires – the live, neutral and earth wires. In a plug, the live wire (brown) and the neutral wire (blue) are the two wires that form the complete circuit with a household appliance. The earth wire (green and yellow) does not normally form part of the circuit and is included as a safety wire.
When one layer of insulation is breached, the second layer keeps the user from receiving an electrical shock, possibly being electrocuted. Double insulation may also remove the requirement for a ground connection.