The Appliance Conductor
Several types of appliance insulation are used on the conductors in home appliances. Some appliance conductors have no insulation at all for instance, a terminal where it attaches to a timer or, in some instances, conductors within an enclosure such as a range console that carry current to a number of switches mounted very closely to each other. Yet even these are insulated from the cabinet-and from surrounding terminals by air space. Other appliance conductors are insulated with an asbestos-impregnated or heat-resistant thermoplastic insulation which serves to protect the conductor from heat. Most conductors in modern home appliances are insulated with a plastic covering that is highly resistant to cracking, breaking, deterioration from oil, and exposure to moisture. Also most conductors in appliances consist of a number of strands, or small wires, instead of a single large wire. This allows more flexibility.
Even with conductors (the simplest single component in a home appliance) pride in craftsmanship is necessary. Though a problem will seldom be directly attributable to a broken appliance conductor, you'll constantly be working with conductors in replacing timers, controls, etc. You will find it necessary to loosen connections and remake them, and sometimes to even change the connections. Wherever conductors are involved, handle them with care.
The Appliance Switch
A appliance switch provides a means of opening and closing a conductor to control the circuit. Switches come in all shapes and sizes, and range from simple, double-contact switches to highly complex switching appliance devices such as a timer in an automatic washer. But here again, more complex appliance switches are simply a matter of multiple arrangements of a single switch.
To understand what a appliance switch does, suppose you have a battery, acme conductors, and a light connected into a simple electrical circuit to make the light burn. With a wire cutter, you snip one of the conductors, and then strip the insulation from the two cut ends of the wire. You soon find that touching the two cut ends together closes the circuit and allows the lamp to burn, and that taking them apart opens the circuit, and the light goes out. We can put a switch in the circuit at this point, and have the switch perform the same function of turning the light on and off. This is all any switch does, regardless of the means used to initiate the switch in action it opens and closes the circuit. It's a very important operation.
Appliance switches are highly specialized, and in many cases, are designed on purpose for the duties to which they are applied. Miniature micro-switches require very small space, yet perform their switching functions at exactly the right time to get the job done. Where heavy loads are involved, large heavy-duty switches control the load with a minimum of arcing due to the fast snap-action of the switch contacts and the material from which the contacts are made. This is one of many good reasons for always using the appliance manufacturer's specified component as a replacement.
Except in the case of the leaf switch, there's usually some sort of attached to the contacts themselves. This may be in the mechanism form of a toggle, such as that within a light switch in a home. A toggle, usually spring-loaded, provides a convenient means of initiating the appliance switching action quickly, thus reducing arcing. In some cases, a device called a appliance solenoid is attached to provide the mechanical action initiated electrically from a remote location. In any case, the switch still performs the same function as touching the two wires together it completes the circuit to the load.
In home appliances, the contacts of the switch (the two surfaces that meet to complete the circuit) are critical. If they don't meet perfectly, there's some resistance to the electrical flow. Resistance means heat, and heat will soon destroy the switch contacts. If the switch contacts are badly pitted or burned, the switch should be replaced. In cases of mild pitting, they can often be cleaned, but only if you catch them in time to prevent severe pitting of the contacts. The best method of cleaning pitted switch contacts is first of all to use a point file, the type used for automotive points (which again are a type of simple switch). Then, the contacts should be cleaned.