Page 661 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 11 Electrical principles and processes for building services engineering

Electrical company isolator LABEL − Safety
electrical
connection
DO NOT REMOVE
Metal gas
pipe

100 A 16 mm 2
Main earthing terminal
10 mm 2
10 mm 2 Gas meter
LABEL − Safety electrical
connection DO NOT REMOVE
Metal water pipe
Water Gas
service service
pipe pipe

p Figure 11.7 TN–S system

TN–C–S system

This system is also known as a protective multiple earthing system, or PME.
It relies on the neutral being earthed close to the source of supply and at points
throughout the distribution system. There is also a neutral-to-earth connection
at the intake of the installation. The ‘C’ means the supplier uses a combined
earth and neutral. The ‘S’ means the earth and neutral are separate within the
customer’s property.

Electrical company isolator Service protective LABEL − Safety
conductors electrical
connection
DO NOT REMOVE
Metal gas
pipe

Main
switch
100 A
16 mm 2
Main earthing terminal
10 mm 2
10 mm 2 Gas meter
LABEL − Safety electrical
connection DO NOT REMOVE
Metal water pipe
Water Gas
service service
pipe pipe

p Figure 11.8 TN–C–S system

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