Most ovens or cookers are simple machines. They operate off either a gas main (or bottle) or electricity to provide the heat you use to cook your food.
Note that there is a difference between the oven and the hobs. Even when the hobs are an integral part of your unit, they are a technically separate item, which is fed separately and which will be serviced and fixed separately. This is true of all ovens, from the largest ranges to the smallest combinations.
All electric ovens and hobs work by passing a current through a heating element. The final temperature achieved by the element is dictated by the temperature dial on the front of the cooker. It is common for the electric oven to measure its temperature in degrees centigrade.
Generally speaking, the electric oven is composed of the following parts: the heating element; the fan (if it is a fan assisted model); the door; and the door seals. The shelves aren't strictly parts, at least not in the conventional repair and maintenance sense, as they are designed simply to hold the pots and pans in which food is cooked.
In terms of electric ovens, most of the faults are to do with the element itself. It's important to note at this point that some spare parts, with which any fault is fixed, are recommended as manufacturer's own (these are often referred to as OEM in the trade); while others (such as door seals) may be made by anyone as long as they do the job properly SO a Bosch electric oven, for example, may need Bosch oven spares where faulty active parts (like the element) are concerned.
The first thing to do with any oven, if you are going to work on it, is to turn the power off at the wall, remove the fuse from the switch and disconnect the grounding wire. This will remove the danger of a minas electric shock, which can be fatal. It is also important to note, for this precise reason, that any work done by an unqualified electrician on any electrical appliance is done entirely at his or her own risk, and may cause death if done improperly.
Before you start fiddling with the element itself, think about what else could be causing the fault. If your oven isn't heating up to a temperature that cooks food properly, or if you think it is colder than it used to be, you may have a faulty door gasket. This can be tested very simply. Turn the oven on, wait for it to heat up a while and then pass your hand lightly around the edges of the door (not actually touching it, just waving in front of it). If you feel the heat, the gasket is gone.
A replacement gasket should fit the model and make of your oven. You may be required to fit OEM gaskets, or you may be able to find a generic sized gasket to do the job.
It may also be the case that the oven's thermostat is not working. To determine if this is true, "cook" an oven thermometer for 20 minutes, in the middle of the oven bay. If the temperature reading on the thermometer differs by more than 25 degrees from the temperature you set the oven to cook at, you need to recalibrate or replace the thermostat.
About Author: Annie Hawthorn is a qualified electrician and cooker engineer. She uses Bosch oven spares to repair Bosch ovens.