2. Notes taken from Gillette’s Designing with Light

3.  Atoms are the smallest complete building block in nature  Atoms are made up of:  Protons - positive charge  Electrons - negative charge  Neutrons - neutral charge

4. AA stable atom ## of electrons in orbit around the nucleus = # of protons in the nucleus IIe. Hyrdrogen Electron Nucleus

5. LLaw of Charges LLike charges repel and unlike charges attract TTwo protons would defy attempts to be close together SSame with electrons AAn electron and proton would stick together

6.  Valence shell: the outermost plane of orbiting electrons in the structure of an atom  Weak force holds electron in orbit  Free electrons: an electron that has broken away from its “home” atom to float free  Copper

7.  Electrical current  The flow or movement of electrons through a conductor

8. AAmpere: the unit of measurement of electrical current PPotential: the difference in electrical charge between two bodies; measured in volts VVolt: the unit of measurement of electrical potential

9.  There are two types of electrical current:  Direct current (DC)  The flow of electrons in one direction. AKA: Batteries  Short distances

10.  There are two types of electrical current:  Alternating current (AC)  Transmitted over long distances  The flow of electrons is reversed on a periodic basis.  Utility companies http://www.answers.com/topic/alternating-current

11.  3 parts  Source: the origin of electrical potential  battery or 120-volt wall outlet  Load: a device that converts electrical energy into another form of energy  Lamp or motor  Circuit: a conductive path through which electricity flows  Wire or cable

12. Series  In a series circuit all of the electricity flows through every element of the circuit  If any of the loads don’t work then the circuit will be broken, the electricity won’t flow, and the remaining loads won’t work either

13. Series www.berkeleypoint.com/images/series.jpg

14. Parallel  In a parallel circuit only a portion of the electricity flows through each of the branches of the circuit  If one load on a circuit doesn’t work then the electricity will continue to flow in the rest of the circuit and the other loads will continue to work

15. Parallel www.berkeleypoint.com/images/series.jpg

16. The Combination Circuit  Combines the principles of the two primary circuits.  Any electrical circuit that uses a switch to control a load is an example of a combination circuit.

17.  Ohm’s Law  As voltage increases, current increases; as resistance increases, current decreases  Resistance  Opposition to electron flow within a conductor  Depends on chemical makeup  Measured in Ohm’s  Low-voltage systems

18.  Ohm’s Law  I=current in amperes  E=voltage in volts  R=resistance in ohms  I=E/R  E=IR  R=E/I

19.  Power Formula  Higher voltage  Watts  Unit of measurement of power required to do work  Amount of electrical energy converted or consumed  Converted into light, heat or mechanical energy

20.  Power Formula  “PIE”  P=power in watts  I=current in amperes  E=voltage in volts

21.  Power Formula  “PIE”  P=power in watts  I=current in amperes  E=voltage in volts  P=IE  West Virginia  W=power in watts  V=voltage in volts  A=current in amperes  W=VA

22.  Dimmer Voltage = 120VAC  Dimmer can handle 20 amperes of current  What is the maximum safe load that can be placed on this dimmer

23.  How many 575W instruments can you plug into a 2400W dimmer with cable that can carry 20 amperes of current?

24.  How many 750W instruments can you plug into a 2400W dimmer with cable that can carry 20 amperes of current?

25.  System Voltage = 120VAC  14 gauge cable connecting the instruments can carry 15 amperes  How many 500 watt instruments can be loaded onto a dimmer?

26.  Conductor  Any material with an abundance of free electrons  Water, copper, silver, gold, aluminum  Insulator  Any material with few free electrons  Air, glass, paper, rubber, most plastics

27.  Created when a large SURGE of current causes a portion of the conductor to explosively melt

28.  Provides a low resistance path for the electricity to follow in case of a short circuit between the hot wire and the devices metallic housing http://sol.sci.uop.edu/~jfalward/physics17/chapter8/plugwithground.jpg

29.  Electrical cable containing hot, neutral and ground wires  Connects lighting instrument to the power source

30.  Plug  Male portion of a connecting device  Receptacle  Female portion of a connecting device

31.  Many hand tools do not have ground pins  Instead they have an outer plastic insulation that protects you from a short circuit

32.  The grounding point  Usually a metal rod driven into the ground or an underground metal water pipe http://en.wikipedia.org/wiki/Image:HomeEarthRodAustralia1.jpg

33.  HOT = BLACK, occasionally RED  GROUND = GREEN  NEUTRAL = WHITE

34.  Greater current in system than it was designed to handle  Fuse and circuit breaker protects from overload  Must have matching amperage as system

35.  Fuse  Contains a soft metallic strip that melts when the current exceeds what the system is designed for  Must be replaced when “blown” http://www.m- 99.co.uk/Car_Audio/Car_Fuses/gold _fuse.jpg images/jpegs/fuse30a.jpg images.orgill.com/200x200/4180923.jpg

36.  Circuit Breaker  Like a switch  Bimetal strip flexes to trip circuit if overloaded cache.smarthome.com/images/7103.jpg

37.  1. If you don’t know what you are doing, don’t do it. Ask for help.

38.  2. Use tools covered with plastic or rubber insulation

39.  3. Use wooden or fiberglass ladders

40.  4. Disconnect device from circuit before you work on it.

41.  5. Use common sense  Don’t touch bare wires  Don’t work in damp locations or put drink where it could spill  Don’t intentionally overload circuit  Don’t try to bypass fuse or circuit breaker

42.  6. Maintain ground circuits

43.  7. Check cables and connectors periodically. Replace cracked, chipped or deteriorating equipment

44.  8. Keep cables and connectors clean.

45.  9. Store cables neatly with ends plugged together and tied

46.  10. Disconnect plug by pulling on body of plug.

47.  11. Ensure all elements have same electrical rating.