If you're planning to undertake a testing and tagging course, or are sending an employee to undertake this safety training, you might have come across several terms such as single and three-phase equipment as well as earthed and double insulated devices. Here are some explanations to provide you with a working knowledge.
Single And Three Phase Equipment And Systems
Testing and tagging are undertaken on portable electrical equipment, such as computers and coffee machines, as well as electrical manufacturing equipment connected to power via flexible electrical cords. These might be industrial printing and binding machines, for example. Testing covers both single-phase and three-phase equipment.
Single-phase electricity is that which is supplied in standard homes at 240 volts. This electrical current is strong enough to run items such as toasters, microwaves, hairdryers and also some large appliances. Phase three electrical circuits are connected at 415 volts, providing a stronger current for larger industrial and domestic machines. Thus single-phase or three-phase power refers to the capacity of your electrical system and how it's set up.
Earthed And Double Insulated Devices
Other essential distinctions — earthed versus double insulation — refer to the different ways appliances and machines are constructed to be safer when it comes to electricity. Typically, devices are classified as class one or class two.
Class one appliances are those that are earthed. These devices have a wire connecting their case to the earth. Imagine a faulty metal kettle, for instance, where the body becomes live so that it's carrying electrical current. If you touched its surface, you might get electrocuted. If the appliance is earthed, however, the current in the kettle's metal body will travel through the earth wire and go to ground — rather than through your body to possibly cause immense damage or death.
Class two products are made safer in a different way: with a double layer of insulation that won't conduct current. Thus, if the body of a metal drill, for example, became live, you would be safe because of the insulation that blocks the current from travelling through to your hands, if you were holding it. These products will either have the words 'double insulated' written somewhere on their surface or they'll have a symbol of a square within a square to signify this.
Thus an Electrical Test and Tag process covers both single-phase and three-phase equipment. These machines might be class one or two, depending on the way they're constructed to be safer.
Contact a test and tag service to learn more.
