16th Edition (reference only) – NOW superseded by the 17th Edition IEE Regulations.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

7.18.1 - Introduction

There is no section 610 in BS 7671, although the intention is that it should be reserved for medical locations and associated areas. The following is thus based on Chapter 9 of Guidance Note 7, which in turn depends on draft lEG Publication 364. The draft standard excludes medical electrical equipment, which is covered by IEC 601-01 : 1988 or BS 5724 : Part I: 1989 and BS EN 60601-01. There can be little doubt that before long this material will become part of the Regulations. Medical locations are often hospitals, but may also include private clinics, medical and dental surgeries, health-care centres and dedicated medical areas in the workplace.

The use of medical electrical equipment is split into three categories:

1. - Life-support: infusion pumps, dialysis machines and ventilators;

2. - Diagnostic: X-ray machines, magnetic resonance imagers, blood pressure monitors, electroencephalograph (EEG) and electrocardiograph (EGG) equipment;

3. - Treatment: surgical diathermy and defibrillators,

This equipment is increasingly used on patients under acute care. Supplies to it require enhanced reliability and safety, as well as measures to reduce electromagnetic interference.

Shock hazards are covered in {3.4} and indicate that currents as low as 10 mA passing through the human body can result in muscular paralysis (an inability to move) followed by respiratory paralysis (an inability to breathe). At about 25 mA ventricular fibrillation (loss of normal heart muscle rhythm) may occur and may be fatal.

The impedance of the human body (see {3.4.2}) may be considerably reduced during certain clinical procedures. For example, the skin resistance is reduced during surgery and defensive capacity either reduced by medication or removed altogether while anaesthetised. Special hazards occur during heart surgery, where electrical conductors may be placed within the heart , or with the use of conductive catheters. Under these conditions currents as low as a few tens of micro-amperes may well result in death.


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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