At times you will need to decide if you require 3 core or 2 core cable. Basically cables are two cores ( active and neutral ) plus a third ( Earth/ground ) cable.
Where the fitting you are wiring requires an earth then three core cable is required. Brass lampholders all require an earth. Bakelite and porcelain lampholders are not conductive and so do not require an earth.
It may be that your light shade or cage make earthing mandatory. If in doubt you should consult an electrician.
We supply SAA approved cables for use in Australia and New Zealand. CE approved cables for 240 Volt applications worldwide and UL Listed cables for use in North America.