The underlying principal for frequency of testing is that the duty holder (i.e. the person with the equipment "within there control") with the advice of the test company and or competent person, when necessary must assess the need for testing the equipment against the following: 

1. Type of equipment (portable, hand-held or transportable).
2. Style of use (continuous, infrequent, rough).
3. Age of the equipment.
4. If regularly moved or transported and by what means.
5. Type and competence of personnel using the equipment.
6. Environment of usage (outdoors, construction sites, hazardous atmospheres etc).
7. Results of previous tests.
8. Manufacturer's recommendations.
9. Effect of any modifications or repairs to the equipment.
   
   
   Re-test frequency can be as long as 4 years and as little as 3 months and sometimes before use (hire equipment) the overwhelming majority of business's and organisations base there test regime on an annual test (depending on equipment requirements) as the most practical and safe approach to there testing program.

• Class 1 equipment is dependant on an earth connection for its safety eg: toaster.
• Class 2 equipment has no earth connection and relies on insulating materials for its safety commonly known as double insulated.eg: hair dryer. It can normally be identified by a square with-in a square symbol. 
• Class 3 equipment relies on a reduced voltage to protect eg: mobile phone charger.
• Verifying the class of equipment is not always easy. By looking at the type of equipment and environment, combined with the type of user will give an indication of how often equipment should be visually inspected and formerly inspected and tested.

1. Portable  eg: toasters, kettles etc.
2. Hand held eg: hair dryers,drills etc.
3. Movable eg: tumble dryers, microwave ovens etc.
4. Stationary eg: cookers, washing machines etc.
5. Fixed eg: hand dryers, towel rails etc.

• Example:
• Do the users know what dangers to look out for!
• Do your people know when or why faults are to be reported!