On Thu, 5 Aug 2010 12:47:23 -0700 (PDT), Higgs Boson wrote: all kinds of previou stuff snipped -
Current code requires split receptacles on the countertop - at least here in Kitchener/Waterloo Ontario. Adding a dedicated line to the microwave won't give you that - while adding the split will give you a "dedicated" line for the microwave (which is allowed, I believe, to also service the gas oven)
It is a duplex receptacle that has been fed with a 3 wire 220 volt feed, split to 2 110 volt (nominal - I know, generally 230 and 115, but that's just semantics) circuits - also referred to by some on the group as an "edison" circuit, I believe.
The microwave and oven are permanetly (more or less) in one place, and generally not within teach of the sink or water taps, whereas the countertop receptacles can feet things like portable mixers etc that can get within reach of the sink - where you could hold a (leaky) appliance in one hand and touch the sink or tap with the other. Without a GFCI you could get a nasty shock. With a GFCI the breaker will trip and you usually will not even get a tickle.
No, like I said, replace the breaker FIRST as it is about 99.999% likely that it is defective, given the scenario described. What make panel do you have? Certain brands are much more succeptible to failure.