1. ELECTRICAL PRINCIPLES
Electricity is the major power source of stationary equipment
Uses:
Driving Machinery
Lighting
Heating
Cooling
Knowledge of electricity is essential for safe use of electrical equipment

2. Electricity- a form of energy that can produce
Electricity- a form of energy that can produce light, heat magnetism and chemical changes
Light- produced by heating a special metal element or filament in a vacuum tube called a “bulb”. Electricity flows through certain gases causing them to glow
Insulator- provides great resistance to the flow of electricity
Materials:
rubber-glass-vinyl-air

3. Amperes- measure of the rate of flow of electricity in a conductor
Volts- measure of electrical pressure
Watts- measure of the amount of energy that can be completed by amps and volts
Formulas:
Watts=volts x amps
Volts=watts x amps
Amps=watts x volts W V A

4. Fluorescent lamp- glows as a result of electricity
Fluorescent lamp- glows as a result of electricity flowing through a gas
Heat- is produced when electricity flows through metals with some difficulty
Resistance- tendency of a material to prevent electricity to flow
Conductor- metal permits electricity to flow easily
Materials:
silver-aluminum-copper

5. E = I X R used in outdoors used in wiring for homes
heat develops in implements
Ohm’s Law: used to measure a material’s resistance to the flow of electrical current
E=volts
I=amps
R=resistance
E = I X R

6. Magnetism- force that attracts or repels iron or steel
- permanent magnet
- when iron or steel holds its magnetism
2 ends or poles
- north
- south
Opposites attract/likes repel

7. Magnetic field- force between 2 objects
Electric Motors- principle of magnetism is the basis upon which electric motors operate
Reverses the Polarity: reversing the direction of current flow
Electromagnet- unit is called
Commutator- reveres the current flow in an electric motor
Armature- rotating magnet

8. magnetic forces around the armature are called the “field”
Generators & Alternators- produce electricity
Generator- produces current (direct)
- flows one way
Alternator- produces current (alternating)
Turbine- high speed rotary engine driven by water-steam-gas
Circuits- circle of electricity
- open circuit- broken
- closed circuit- together

9. Short Circuit- flow through the circle & back
Short Circuit- flow through the circle & back to the source too rapidly
Grounding- connection between a piece of equipment & the earth
- ground rod- steel or copper
- ground wire- bare
* channels stray electricity
Electricity Safety: 2 deadly hazards with current
- shock
- fire

10. Shock- body’s reaction to a current
GFCI- Ground Fault Circuit Interrupter
-cuts off electricity if it leaves the pathway
Electrical Wiring: Systems have to be:
-safe -convenient -neat
-expandable -provide sufficient current
Service Entrance: Power company provides
-transformer -service drop -appropriate wiring

11. Entrance Head- waterproof device used to. attach exterior wires to
Entrance Head- waterproof device used to attach exterior wires to interior wires
Transformer- converts high voltage to volts-usable form for homes
- step up - step down
Service Drop- assembly of electrical wires- connectors & fasteners used to transmit electricity from the transformer to the entrance head

12. Service Entrance Panel- box with fuses or. breakers where
Service Entrance Panel- box with fuses or breakers where electricity enters a building
Meter- measurement of electricity in kilowatt hours-Kilo means 1, 000
Watt Hour- use of 1 watt for 1 hour
Kilowatt Hour- use of 1, 000 watts for 1 hour
Reading a Meter: the last number passed by each pointer is read

13. 1st & 3rd dials turn counterclockwise
2nd & 4th dials turn clockwise
Branch Circuits- branch out to a variety of places for many purposes
Fuse: plug or cartridge containing a strip of metal that melts when more than a specified amount of current passes through
Circuit Breaker:

14. switch that trips & breaks the circuit when more than specified amounts pass through it
- reset breaker after it trips
Types of Cables:
3 systems of wiring:
-Non-metallic sheathed
-Armored cable
-Conduit

15. Non-metallic Sheathed Cable:
-copper/aluminum
-waterproof
-approved for burial
Armored Cable:
-flexible metal sheath
-mechanical damage protection
Conduit:
Tubing consists of individual insulated wires
EMT-electrical metallic tube

16. Conduit can be:
-rigid
-bendable
-provide the most protection
Wire Type & Size:
Copper
Aluminum
Wire size designated by gauge: lower the gauge larger the wire

17. Strands- small wires placed together are called “bundles”
- improves conductivity & flexibility
- electricity carried on outside of wire
Voltage Drop- refers to a loss of voltage as the electricity travels along a wire
-larger the wire, less voltage drop
-longer the wire, more voltage drop
Wire ID: factors to determine wire
-outer covering
-number of wires

18. -individual wire covering
-cable construction
Wire type is stamped on outside
Type T- dry locations
Type TW- dry or wet locations
Type THHN- dry locations, high temperatures
Type THW & THWN- wet locations, high temperatures
Type XHAW- high moisture & heat resistance

19. Type UF- buried in soil (not concrete)
NEC- National Electric Code
Hot Wires- colors (positive)
-black -red -blue
Neutral Wires- color
-white
Ground Wire- colors
-green -bare
Typical markings: 12-1, 12-2, 12-3 with ground

20. INSTALLING BRANCH CIRCUITS
NEC- controls restrictions on wiring
Wiring Boxes:
-metal
-plastic
-hold work in place
-nail or screw to framing
-contains all electrical connections
-square/octagonal/rectangular

21. Wire Nuts- insulated, solder-less connectors
Receptacle- device used for receiving electrical plugs
Switch- device used to stop the flow of electricity
Duplex Receptacle- both outlets are on same circuit
Single-Pole Switch- designed to be the only switch in the circuit
Knock Out- partially punched impression

22. Ground Clip- attaches ground wire to a box
Testing a Circuit:
Continuity Tester- device used to determine if electricity can flow between 2 points
Continuity- connected-ness
3 way switch- permits a light/receptacle to be controlled from 2 locations