Kitchens are where the action is. Kitchens are where families spend a lot of time. People cook, do paperwork and homework and socialize. It's no wonder it's one of the most electrically complex areas of the house. Quite simply, people use a lot of electricity there. You heat a lot of things all at once, you use appliances, you need lots of light to see. Older homes often have 1 circuit for the kitchen outlets and lights, often fed from the basement below where the washer and dryer are. Well, 30 years ago, we weren't using the microwave ovens, toasters and toaster/ovens, coffee makers, dishwashers like today.
In the interest of safety, the electric code looks to reduce overloaded wires (fire hazard), extension cords (tripping and damaged wiring hazard) and dangerous electrical situations (shock hazard). Over time, the code has required more and larger capacity circuits than before, as well as GFI outlets for personal safety. Although older homes may not have the specifications we need today, kitchen remodeling will require you to comply with today's code. Remember that the code is modified over time based on problems and hazards that have been reported in the real world. Here's a rundown of the code requirements and why:
At least two 20 amp circuits for the kitchen counters, and not shared with anything else in the house except the dining room outlets. This is to prevent tripping circuit breakers from too many things running at once on the circuit. Even small microwave ovens can use as much power as a hairdryer. A look at the chart below will give you some idea of the power needs in the kitchen. As a comparison, note how little power a 60 watt bulb needs.
Outlets for the kitchen counter need to be protected by a ground fault circuit interrupter (GFI or GFCI). This is usually a special outlet with push buttons for Test and Reset on it. One of these special outlets can protect other normal-looking outlets on the counter. Newer homes will probably have at least 2 of these special outlets on the counter. Refer to the GFCI section for more general information.
Since counter outlet circuits are supposed to be dedicated to the countertop, other items such as refrigerator, lights, hood, dishwasher, garbage disposal are not to be on the same circuit.