The first thing that comes to mind, is why do you want to change what you have?
The code book can be open to interpretation and this is one of those things that you'll hear electricians argue over what's correct. Here's what the code books says, rephrased into plain English:
You have to have split receptacles along the back of your kitchen counter so that at no point along the back of the wall is more than 900mm from a plug. It can't be directly behind the sink however and the sink itself does not count in that 900mm measurement.
Alternatively, you can install 20amp plugs. You must have at least 2 of them and adjacent plugs must be on different circuits. No circuit can have more than 2 plugs on it.
For a while this was a choice given to the electrician to pick from.
As of Jan 1st 2003 a new requirement came into effect requiring that any plug within 1m of the kitchen sink must be GFI protected. If you refer to the above rule about 900m, that means that the plugs on either side of the sink must be GFI. Since there are no split GFI plugs, it essentially made the split plug rule void.
So your choices now:
Do you have #12 wire? If you do, you can get 2 x 20amp GFIs, connect one to one circuit and the other plug to the other circuit. Cap off the extra wires and you're done. However it's extremely unlikely that your wire is #12, so it's probably not an option. Do not do this if you have #14 wire.
Put regular plugs, split as normal and put a double pull 15amp GFI breaker (assuming they make these, I honestly don't know - never installed one).
Remove the #14 wire and replace with 2 runs of #12 wire and put 20amp GFI plugs in your kitchen.
Or, just leave it as it. If it's an old house, you're within the code of when it was made and it's fine to leave it as is. Unless you're doing some major renovation, in which case ESA may require you to "upgrade" your wiring to current code.
