To test portable appliances you must be a "Competent" person. Page 13 of the IEE Code of Practice defines competency as “A person possessing sufficient knowledge or experience to be capable of ensuring that injury is prevented. Technical knowledge or experience may include:
1. Adequate knowledge of electricity.
2. Adequate experience of electrical work.
3. Adequate understanding of the system to be worked on and practical experience of that class of system.
4. Understanding the hazards that may arise during the work and the precautions that need to be taken.
5. The ability to recognize at all times whether it is safe for work to continue.”
It also refers to regulation 16 of the Electricity at Work Regulations which says “No person shall be engaged in any work activity where technical knowledge or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may be appropriate having regard to the nature of the work.”
Basically, to be a “Competent Person” you need to demonstrate competency. This is usually done by undertaking a course of instruction by a person who is qualified, passing an exam to confirm the underpinning knowledge, being assessed as being competent by undertaking a practical demonstration of basic skills and being certified as such.