It depends if you are using this electrode as an anode or as a cathode and also on your electrochemical setup (including the use of a reference electrode).
Thanks Loraine. The carbon paste electrode is actually my working electrode, Ag|AgCl reference electrode while the platinum wire is my counter electrode.
Normally, the electroactive area of an electrode should be greater that its geometrical area. This means that your electrode (especially that it's your working electrode) has a specific area (a porosity) which is an advantage for electrochemical reactions and conversions. If both areas were equal, your electrode has no porosity at all since it would considered as flat as its surface. So if you are obtaining an electroactive area greater than the geometrical one, it is because your electrode has a specific area (porosity).