16th Edition (reference only) – NOW superseded by the 17th Edition IEE Regulations.

chapter 5

chapter 6

Inspection and Testing
  8.1 - Introduction 8.5 - Insulation tests
  8.2 - Inspection 8.6 - Earth testing
  8.3 - Testing sequence 8.7 - Test instrument requirements
8.4 - Continuity tests 8.8 - Supporting paperwork

8.1.2 - Why do we need inspection and testing?

There is little point in setting up Regulations to control the way in which electrical installations are designed and installed if it is not verified that they have been followed. For example, the protection of installation users against the danger of fatal electric shock due to indirect contact is usually the low impedance of the earth-fault loop; unless this impedance is correctly measured. this safety cannot be confirmed. in this case the test cannot be carried out during installation, because part of the loop is made up of the supply system which is not connected until work is complete.

In the event of an open circuit in a protective conductor, the whole of the earthed system could become live during the earth-fault loop test. The correct sequence of testing {8.3} would prevent such a danger, but the tester must always be aware of the hazards applying to himself and to others due to his activities. Testing routines must take account of the dangers and be arranged to prevent them. Prominent notices should be displayed to indicate that no attempt should be made to use the installation whilst testing is in progress.

The precautions to be taken by the tester should include the following:

1. - make sure that all safety precautions are observed

2. - have a clear understanding of the installation, how it is designed and how it has been installed

3. - make sure that the instruments to be used for the tests are to the necessary standards (BS 4743 and BS 5458) and have been recently recalibrated to ensure their accuracy

4. - check that the test leads to be used are in good order, with no cracked or broken insulation or connectors, and are fused where necessary to comply with the Health and Safety Executive Guidance Note GS38

5. - be aware of the dangers associated with the use of high voltages for insulation testing. For example, cables or capacitors connected in a circuit which has been insulation tested may have become charged to a high potential and may hold it for a significant time.

The dangers associated with earth-fault loop impedance testing have been mentioned in {5.3}.


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Extracted from The Electricians Guide Fifth Edition
by John Whitfield

Published by EPA Press Click Here to order your Copy.

Click here for list of abbreviations