Portable Appliance Testing - Class of Construction

Class of Construction

Electrical appliance classes are differentiated by a series of IEC protection classes. The protocols for PAT Testing vary by appliance class.

  • Class I – Single insulated wiring, which requires an earth connection. There is no symbol for a Class I product so if a rating plate has no symbol on it then it is usually Class I.
  • Class II – Double insulated wiring, The earth clamp is still connected during the insulation test even though no earth on appliance. Class II is indicated by double box.
  • Class III – These are appliances that are supplied at a low voltage (usually called Separated Extra Low Voltage) which must be less than 50 V. These appliances are supplied with a transformer supply that is also marked.

The earth lead is connected to metal parts on both Class I and Class II appliances. For "Class I" during the earth test to prove continuity between earth pin and metal parts on the appliance. For "Class II" during the insulation test to prove the insulation between active-neutral and the metal parts of the appliance. ie there is no leakage from mains coming into the appliance to the metal parts that are exposed.

Read more about this topic:  Portable Appliance Testing

Famous quotes containing the words class of, class and/or construction:

    Money couldn’t buy friends, but you got a better class of enemy.
    Spike Milligan (b. 1918)

    I read, with a kind of hopeless envy, histories and legends of people of our craft who “do not write for money.” It must be a pleasant experience to be able to cultivate so delicate a class of motives for the privilege of doing one’s best to express one’s thoughts to people who care for them. Personally, I have yet to breathe the ether of such a transcendent sphere. I am proud to say that I have always been a working woman, and always had to be ...
    Elizabeth Stuart Phelps (1844–1911)

    There’s no art
    To find the mind’s construction in the face.
    William Shakespeare (1564–1616)