ADS – Automatic Disconnection of Supply – This is what prevents a dangerous occurrence arising in case of a fault condition. It is made up of basic protection and fault protection. It refers to the fact that a combination of methods of protection will disconnect the supply of electricity if a fault occurs.

Current carrying capacity – The amount of electrical current a cable or piece of equipment can handle safely.

Electrical current – The movement of electrons through a conductor

Electrical potential – This is the amount of work that is required for an electric charge to move from one point to another.

Fault current – A current arising from a fault in an electrical installation.  

Over current – this is where the current exceeds the rated current of the electrical equipment; with over current the circuit is considered unhealthy.

Overload current – Overload current is where more current is drawn through the circuit than it has been designed for, but the circuit is still considered healthy.

Prospective fault current – The amount of current that could potentially flow between conductors in the event of a fault.

Resistance – The amount of opposition to the flow of electricity through a conductor.

Selectivity – This is the act of selecting your protective devices, so only the one you want operates when a fault is detected.

Short circuit current – This is a fault current between two live conductors; Such as between line and neutral. In this instance the circuit is treated as unhealthy.

Voltage nominal – This is the voltage by which an installation is designated. There are three bands which are designated, and they are:

• Extra low voltage = 50V and below for AC systems.
• Low voltage = Greater than Extra low voltage, but doesn’t exceed 1000V AC between conductors or 600V AC between conductors and earth.
• High Voltage = Greater than low voltage.