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Electrical Supply and Earth Continuity

Exam revision materials for Plumbing Level 2&3 and ACS Gas Safety test

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Central Heating Wiring Diagrams

Types of Electrical Systems

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Electrical tests

Testing Equipment

Types of Electrical Tests

Central Heating Wiring Diagrams

Central Heating Diagrams

Electrical Current

Types of Electrical Systems


Fuse Types

Safety Requirements

Wires and Cables

Cable Protection

Cable Sizing

Cable Types

Electrical Circuits

Electrical Bathroom Zones

Electrical Components

Electrical Fittings

Switches and Sockets


Earth Bonding

Earth Bonding

TN-S System

  • underground cable
  • earth comes into the building the same way as the phase and neutral
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TT System

A TT system has the neutral running in the supply cable(s) as normal, and the earth from the installation is connected to an appropriate Earth Electrode inserted into the ground. An RCD is essential in an installation formed by a TT earthing arrangement.

  • via two overhead conductors
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TN-C-S System

A TN-C-S system has the neutral and earth COMBINED in the Electricity Boards supply cable(s), and SEPARATE with-in the installation, (this being the meter position and onwards).

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