Electrical wiring

[edit] Introduction

Electrical wiring is defined in the IET Wiring Regulations (BS 7671) as ‘wiring systems’, with the following definition:

Wiring as a term in such instances is usually taken to mean ‘cabling’ and the installation of cables within a building.

[edit] Cables and cabling

A cable, in the context of electrical installations in buildings, is an insulated conductor of electricity, usually copper or aluminium, with a protective casing which acts as an insulator. Cables are used to transmit electrical energy or data or telecommunications signals from one point to another.

The usual attributes of an electrical cable include:

• They are flexible enough to be drawn through or laid into a containment system.
• Where appropriate, they can be clipped directly or suspended from a building’s structure.

Flexible cables (often simply called flex cables), comprise finer strands of conductor material, and are used where regular movement or articulation is expected that could damage regular cables.

Cable insulation materials may comprise common plastics such as polyvinyl chloride (PVC), modified synthetic materials, or rubber. Other forms of insulation include mineral powder housed within a metallic outer casing.

The way different cables behave when subjected to fire conditions is the subject of extensive research. Toxic gas emissions, density of smoke and fire propagation speeds can vary widely with different forms of cable. This is a key consideration when selecting materials for buildings.

Since 2017, cables marketed and made available in the European Union (EU) must carry a ‘Euroclass’ classification, categorising their reaction to fire conditions.

--ECA

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