Electric Heaters
Heating coils in furnaces (and hair dryers) which warm the airflow are basically the same.
They have a length of stainless steel wire formed into a coil and supported on insulated prongs.
The wire resists the current and subsequently generates heat
Do not use electricity to heat a space, very inefficient.
alternatively, using electric heat as radiant heat can be efficient for heating only people and not the air.
Electric Lighting
Lights are grouped into circuits and connected to switches from a central panel.
Three and four way switches are used when more than one switch is required on a single circuit, where a switch is desired at each door in a room with two or more entrances for example.
Motors
Only four types of motors are in use.
DC motor = small scale applications and elevators providing continuous and smooth acceleration to a high speed.
Single phase AC motors = many sizes and shapes, typically 3/4 horsepower or less
three-phase induction motors = larger motors, remain in constant rpm, unless overloaded, power factor ranges of 0.7-0.9, extremely reliable characteristically
Universal motor = runs on DC or AC, variable speed based on load, found in mixers, hand drills and the like.
All motors should be protected against overload by thermal relays that shut off the power when it gets too hot.
Capacitors
Simple capacitor is a set of two plates separated by a small insulating layer.
Current is stored in one plate and at some point the entire stored amount is discharged.
they are used to improve the power factor in a circuit helping to improve efficiency and performance.
Receptacles
Commonly know as an outlet
No further than 12 feet apart in residential construction.
Three prong is standard, one being a ground.
All outlets in a large room should not be on the same circuit so if a circuit breaker trips the entire room will not be without power or light source.
Panel boards
A set of fuses or circuit breakers which control the circuit loading in a building (typically breakers switches)
Central distributing point
Each breaker serves a single circuit, overload protection based on size and current carrying capacity of the wiring in that circuit.
Larger buildings will have a main panel (with a main disconnect switch)and sub-panels closer to the areas they are serving.
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