Facebook linkedin twitter
1300 730 699


Electrical equipment testing - Classes of Equipment

Date: 10 March 2018

We've previously mentioned during the test tag course that electricity, as we all know, can be dangerous and can kill. Electrical fatality statistics show that the most potentially lethal situations are: incorrectly connected or broken earth conductors, insulation breakdown or working on live. This is why we will outline electrical equipment testing - classes of equipment and why it's important to know these.

There are two classes of equipment. Class I covers areas such as basic insulation and protective earthed equipment. Equipment in which protection against electric shock does not rely on basic insulation only, but has additional safety precautions, in that conductive accessible parts are connected to the protective earthing conductor in the fixed wiring of the installation in such a way that those accessible parts cannot become live in the event of a failure of the basic insulation.

Examples of Class I equipment includes but is not limited to:

  • Bench grinders
  • Older power tools such as drills, grinders etc.
  • Air compressors
  • Electric concrete mixers


Class II equipment covers double insulated equipment. This is usually manufactured with non-conductive (insulated) enclosure (normally plastic) and is marked with the words double insulated.

  • Class II equipment may also be manufactured with metal enclosures which are double insulated from live parts
  • Class II equipment does not need an earth conductor and should not be earthed.
  • Most modern power tools and equipment which is subject to movement or flexing of the cord fall in to this category. If you are unable to find the symbol which marks as Class II, treat as a Class 1.


You also need to know about cord set as this includes extension leads and detachable leads supplying power to the equipment, such as those used to connect computers, monitors and printers etc. Commonly called power boards Electric Portable Outlet Device (EPOD) have a single means to connect to a power supply, with one or more outlet facilities.

Then there's Residual Current Devices (RCD). RCDs are commonly known as Earth Leakage Circuit Breakers (ELCB) or safety switches. An RCD is an electrical safety device specially designed to immediately switch the electricity off when electricity is detected leaking to the earth at a level harmful to a person using the electrical equipment.

An RCD offers a high level of protection from electric shock but it will not protect in all instances of electric shock Be aware that double adaptors, domestic type power boards and similar fittings are not permitted for construction work and must not be used.

To find out more about our electrical equipment testing, register for one of our test & tag courses here.

< Back to News Items

Test and Tag Online Courses | Copyright © Test Tag Courses | Privacy Policy | Disclaimer | Site Map