Unit switches that are part of an appliance that disconnect all ungrounded conductors are permitted as the disconnecting means. Refer to Article 422 of the NEC for other means of disconnection on the various types of occupancies. When you are grounding an appliance, refer to the NEC, Article 250. Any part of an appliance that may be energized must be grounded except for those mentioned within this article.
A circuit that supplies electrical energy to one or more outlets to which appliances are to be connected is called an appliance branch circuit. These circuits are not to have any permanently connected lighting fixtures that are not a part of an appliance.
The NEC states special requirements for appliance branch circuits. We will go over a few of these requirements.
In dwelling occupancies, small appliance loads, including refrigeration equipment, dining areas, kitchens, family rooms, pantries, and breakfast rooms, should have two or more 20-ampere branch circuits installed (referred to as special-purpose outlets) in addition to the branch circuits previously mentioned. These circuits will have no other outlets except for clock outlets.
At least two appliance receptacle branch circuits will be installed in the kitchen for receptacle outlets. In the laundry room at least one 20-ampere branch circuit will be provided. Again, always refer to the NEC before installing any circuit or equipment to ensure you have the proper number of circuits needed and the correct size wiring and disconnecting means necessary for each branch circuit, appliance, and piece of equipment that you are to install,
We will discuss various appliances that you will encounter throughout the Naval Construction Force (NCF). You may be called upon to install, troubleshoot, and repair all appliances mentioned here, plus others not covered within this chapter.
The purpose of a washing machine is to clean clothes by forcing a mixture of water and a cleaning compound through the clothing regardless of how the machine is constructed.
Washing machines can be classified in various ways, but generally they are divided into the agitator and tumbler types. Each type has advantages over the 7-2 other and may have certain disadvantages, but each will give years of service if properly operated and maintained.
COMPONENTS. - Before attempting any troubleshooting or repairs, you have to understand the components of the washer and their functions. Washers vary in construction, but their operating principles are similar.
Electrical Supply. - Before connecting any washer to a power source, look at the motor nameplate or the manufacturer's manual to determine the correct electrical supply for the washer. Normally, a 120-volt, 60-cycle, 15- to 20-ampere circuit is required. Most machines come with a three-prong power cord that is to be inserted into a grounded duplex convenience outlet according to NEC requirements. UNDER NO CIRCUMSTANCES SHOULD YOU REMOVE THE GROUND PRONG FROM THE PLUG. This prong is a ground that protects the user from electrical shock and possible electrocution.
Timer. - The timer is the heart of the electrical system. It has a motor, an escapement, and multiple- circuit cam switches, all assembled into one unit. The timer (being a synchronous type of motor, like those in clocks) has a small pinion gear that drives the escapement. The escapement is a spring-powered mechanism that advances the time interval. The motor winds up a spring that unwinds abruptly to advance the camshaft the correct number of degrees. A ratchet mechanism in the escapement output gear permits the timer to be advanced manually. The camshaft opens and closes smaller switches in the multiple-circuit cam switch case. These switches control the operation of the washer. All electrical circuits come through the timer. The main ON/OFF switch, operated by a push-pull action of the timer shaft, also is located within the timer housing.
Motor. - The most essential component of a washer is the motor, which is usually a 1/3-horsepower, 120-volt unit. The motor supplies the power that operates the agitator, spins the tub, and operates the water pump. The motor is protected by a thermal overload protector connected in series with both the main and starting windings. The overload protector opens if the windings overheat. Some washers are equipped with two-speed motors and others have reversible motors.
Belts from the motor to the transmission drive the agitator and the tub. Figure 7-1 shows a typical washerContinue Reading