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UNIVERSITA’ POLITECNICA DELLE MARCHE

UNIVERSITA’ POLITECNICA DELLE MARCHE Facoltà di Economia Corso di Laurea in Economia Aziendale La risorsa Sangue Economia e Gestione del Sistema Trasfusionale in Italia e nelle Marche Relatore: Prof. Franco Sotte Tesi di laurea di: Marta Moretti. Anno Accademico 2002 – 2003.

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UNIVERSITA’ POLITECNICA DELLE MARCHE

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  1. Electrical Principles and Wiring Materials Unit #31

  2. Principles of Electricity • Electricity is a form of energy that can produce light, heat, magnetism, chemical changes • Resistance: tendency of a material to prevent electrical flow • Conductor: if electricity flows easily • Insulator: material that provides great resistance

  3. Amps, Volts, Watts • Amperes: measure of the rate of flow of electricity in a conductor • Volts: measure of electrical pressure • Watts: measure of the amount of energy or work that can be done • Ohms: measure of electrical resistance to flow

  4. Ohm’s Law • Ohm = R • Volts = E • Amps = I • Ohm’s Law: E = IR I=E/R R=E/I

  5. Electrical Safety • Shock and Fire • Never disconnect any safety device • Don’t touch electrical items with wet hands or feet • Don’t remove ground plug prong • Use GFI in wet areas • Discontinue use of extension cord that feels warm • Don’t put extension cords under carpet

  6. Electrical Safety • Install wiring according to NEC • Blown fuse or breaker, determine cause • Don’t replace fuse with larger fuse

  7. Electrical Safety • Don’t leave heat producing appliances unattended • Heaters & lamps away from combustibles • Don’t remove back of TV (30,000v when off) • Electric motors lubricated, free of grease etc

  8. Electrical Safety • Keep appliances dry • Don’t use damaged switches, outlets, fixtures, extension cords • Follow manufacturer’s instructions for installation and use of electrical equipment

  9. The path of Electricity

  10. Service Entrance • Power from from power company • Transformer: drops volts from 25,000 volts to 240 volts • Service drop: wires etc from transformer to house • Entrance head: weather-proof at house • Meter: $$$ • Service Entrance Panel (SEP): box with fuses or breakers

  11. Transformer

  12. Service Drop

  13. Service Entrance Panel

  14. Electric Meter • Kilowatthours: how electricity is sold • Kilo = 1000 • Watthour = use of 1 watt for one hour • 100 watt light bulb for 1 hour - 100 watthours • Kilowatthour = 1000 watts for one hour

  15. Electric Meter Box

  16. Branch Circuits • usually begin at SEP • branch out into a variety of places • only 1 motor or; • series of outlets or; • series of lights • use correct size wire and fuse or breaker

  17. Branch Circuits

  18. Types of Cable • Nonmetallic sheathed cable: copper or alluminum wire covered with paper, rubber, or vinyl for insulation • Armored cable: flexible metal sheath with individual wires inside. Wires are insulated • Conduit: tubing with individually insulated wires

  19. Sheathed Cable and Armored Cable

  20. Wire Type and Size • copper • No 14 (14 gauge) = 15 amp circuits • No 12 = 20 amps • No 10 = 30 amps • aluminum use one size larger • lower gauge number = larger wire • No 8 and larger use bundles of wires • current travels on outer surface of wire, so a bundle of smaller wires can carry more

  21. Voltage Drop • loss of voltage as it travels along a wire • lights dim, motors overheat • larger wires have less voltage drop for a given amount of current • longer wire = greater problem • must increase wire size as distance increases

  22. Wire Identification • Type of outer covering, individual wire covering, cable construction, number of wires • Wire type stamped on outer surface

  23. Wire Types • Type T - dry locations • Type TW - dry or wet • THHN - dry, high temps • THW and THWN - wet, high temps • XHHW - high moisture & heat resistance • UF - direct burial in soil but not concrete

  24. Wire Identification • Color coded: black, red, & blue = positive or hot wires which carry current to appliances • White = neutral wires carry current from appliance back to source • Green or Bare = ground all metal boxes and appliances

  25. Wire Identification • Wire Size: 12-2 has two strands of No. 12 wire (black & white) • 12-2 w/g same, with one green or bare • 12-3 has three strands of No. 12 (black, red, white) • 12-3 w/g same, with green or bare

  26. Electrical Tools & Components Modified By: Jake Muller

  27. Objectives Identify wiring tools and wiring components.

  28. Wire sizes and Types

  29. American Wire gaugeWire Diameter in inches

  30. Romex Color Codes • 14-gauge is white • 12-gauge is yellow • 10-gauge is orange

  31. Wire Types 10/ 2 with ground 12/ 3 with ground 14/ 2

  32. Wire types Continued

  33. Electrical Conduit Types

  34. Breaker Box & SID

  35. Recepticles

  36. Light Switch

  37. Single-Pole Switch

  38. Three Way Switch

  39. Light Sockets

  40. Protection Devices

  41. Circuit Protection Devices

  42. GFCI Receptical

  43. GFCI Breaker

  44. Arc Fault Interrupter

  45. Screw Fuses

  46. Knife/Bar Fuses

  47. Common Grounding

  48. Outlet Grounding

  49. Don'ts

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