Electrical Inspection & Testing - Representative Testing

Money is tight so could I just test say 20% as a sample?

Yes you can - as long as you have previous records of testing. But if you have no records how can you defend yourself in a court of law if you do not know the condition of the other 80% which has not been tested?

Would NECTA ever sample test?

If the client has no inspection and testing records or network drawings we strongly advise 100% inspection and testing as far as reasonably practicable, supplemented by the network drawings.
The following flowchart illustrates conditions when comprehensive or representative inspection and testing programmes should be undertaken:

However, under certain circumstances, such as where the client insists and is prepared to take the responsibility of acting against our advice, or where money is so tight that the client cannot afford a 100% programme, even over a number of years, yet he wants to do something to mitigate his risks, then in such cases we can modify our programmes accordingly.