to the 16th Edition IEE Regulations

chapter 5

chapter 6

Special Installations
  --1. - Introduction --2. - Bath tubs and shower basins
  --3. - Swimming pools --4. - Sauna rooms
  --5. - Installations on construction sites --6. - Agricultural & horticultural
--7. - Restrictive conductive locations --8. - Earthing for function & protection
--9. - Caravan, motor homes, caravan parks 10. - Highway power & street furniture
11. - Heating appliances & installations 12. - Discharge lighting
13. - Underground & overhead wiring 14. - Outdoor installations & garden buildings
15. - Installations of machines & transformers 16. - Reduced voltage systems
17. - Marinas 18. - Medical locations
19. - Exhibitions, shows and stands

7.15.2 - Transformers

Transformers are used more widely in the supply system than in the installation itself. The link between the primary and secondary windings of a double wound transformer is magnetic, not electric, so there is no electrical connection with the supply system, or with its earthing system, from a circuit fed by the secondary winding of a transformer. This loss of earthing may be an advantage where electrical separation is required, for example, where an electric shaver in a bathroom is fed from the secondary winding of a transformer (see {5.8.4}).

Step-up transformers must not be used in IT systems. In systems where they are permitted, linked multipole switches must be provided so that the supply is simultaneously disconnected from all live conductors, including the neutral.



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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