'Banana' connectors are available in several sizes - 1, 2, 3 and 4mm. They are single pole and are normally used for connections on test equipment, especially the 2 and 4mm types. For this reason 4mm plugs are also available in touchproof housings for use with high voltages. The pin of the plug is sprung, giving a tight friction-fit into the socket .
Other applications requiring a single pole connector
The connectors are single pole, so only have one terminal. Different coloured covers can be used to identify connections, e.g. red for positive, black for negative, green for earth etc.
The wire is normally terminated to plugs by solder bucket terminals. Remember to thread the wire through the plastic cover before soldering! Some plugs (especially stacking ones) have a hole drilled across the pin, trough which the wire is inserted. It is then trapped when the contact is inserted into the plastic cover. Panel mounting sockets have solder tag connections on the back.