CLASS 1

CLASS 1

In the open plug the three wires connecting to the LIVE, NEUTRAL and EARTH pins. Inside the fire, the brown LIVE wire and the blue NEUTRAL wire connect to a plastic connector. The green/yellow Earth wire connects to the metal case of the fire.

The user is protected from electric shock by the plastic insulation of the connector. This holds the LIVE and NEUTRAL wires in place and prevents them from touching the metal case of this electric fire. This plastic insulation of the connector is known as basic insulation.

If this basic insulation were to fail, say due to excessive movement of the cable where it touches the metal case then the user of the fire can receive an electric shock if not for the fact that the EARTH wire is present.

By connecting to the metal case of the electric fire, the EARTH wire keeps all this metal at EARTH potential. What this means is that it is impossible to get an electric shock even when the metal case of the fire is connected directly to the LIVE voltage. In practice a fuse would blow either in the plug or the main fuse box to protect the user.

In summary, in Class 1 appliances the user is protected by a combination of basic insulation and the provision of an EARTH connection, thus providing two levels of protection. When PAT Testing Class 1 appliances, the Earth Continuity and Insulation Resistance tests are carried out.