HOUSE WIRING NOTES

Electricity  Proton – positive charge  Electron – Negative charge  Electricity = flow of electrons Conductor= electricity passes thru easily - Metal, water, person  Insulator = restricts electrical flow  Rubber, plastic, wood, paper

Circuits  Circuit = path for electricity to flow  Types  Series – one path, if one part doesn’t work, nothing works.  Parallel – more than one path (alternate routes), if one path doesn’t work the others can still work.  Complex – a combination of series and parallel.

Loads/Device  Load - anything that makes electricity useful for us.Light, outlet, anything plugging into outlet, motors  Device – anything that controls the flow of electricity.Switch, breaker, fuse

Measuring Electricity  Voltage – Potential difference, the force to start the flow of electricity. Measured in Volts  Amperage - The flow of electricity in the circuit (current). Measured in amps.  Resistance - The opposition to the flow of electricity. Measured in ohms.

Current  Current is the flow of electricity.  Types of current  DC (Direct Current) A current that flows in one direction only ex. batteries  AC (Alternating Current) Changes direction 60 times per second ex. homes

NEC  National Electrical Code – Sets and enforces a set of rules, regulations, and criteria for the installation of the electrical equipment.

OSHA  Occupational and Safety Health Act – Creates and enforces health and safety standards in the workplace. This organization protects persons in all occupations in the U.S.

UL  Underwriters Lab = test electrical equipment and determine what the uses can be.  You may not use equipment for something it has not been rated for!

OHM’S LAW  Current in a circuit is directly proportional to the voltage and inversely proportional to the resistance of a circuit.  Voltage (E)= Current X Resistance  Volts = Amps X Ohms  Current (I)= Voltage / Resistance  Amps = Volts / Ohms  Resistance (R)= Voltage / Current  Ohms = Volts / Amps E I R volts ampsohms

Practice Ohm’s Law  1. What is the voltage of a circuit with 15 amps of current and toaster with 8 ohms of resistance?  E (volts)=I (amps) x R (ohms) = 15amps x 8ohms = 120 volts  2. How many ohms of resistance must be present in a circuit that has 120 volts and a current of 10 amps?  R (ohms) = E (volts) / I (amps) = 120 volts / 10 amps = 12ohms  3. A light bulb has a resistance of 4 ohms and a current of 2 A. What is the voltage across the bulb?  4. How much voltage would be necessary to generate 10 amps of current in a circuit that has 5 ohms of resistance?  5. An alarm clock draws 0.5 A of current when connected to a 120 volt circuit. Calculate its resistance.

Transformers  Step-down transformer – lowers the voltage  Step-up Transformer – increases the voltage

SAFETY  Safety – Ensure that circuit is disconnected and dead before beginning work on it.  Use tools correctly and for their intended purpose.  Remove all jewelry, watches, and rings to avoid metal-to-metal contact with energized circuits.  Keep the work area dry and free of debris.  Ensure all electrical equipment is properly grounded.  Ladders should only be made of wood or composite material.

POWER  Power is the rate of doing work, measured in watts or volt-amperes.  Power = Voltage X Amperage  Watts = Volts X Amps  Voltage = Power / Amperage  Volts = Watts / Amps  Amperage = Power / Voltage  Amps = Watts / Volts  Kwh = Kilo-Watt Hour = 1000 watts per hour P E I watts volts amp s

SERIES CIRCUIT RULES  1) The current is the same throughout.  2) A break anywhere in the circuit stops the electrical flow in the entire circuit.  3) Resistance is the sum of the individual resistances.  4) Voltage at the source is equal to the sum of the voltages at each resistor.  5) Ohm’s law applies to any part of the entire series circuit.

PARALLEL CIRCUIT RULES  1) Voltage is the same throughout the parallel circuit.  2) A break or opening in any branch does not stop the flow of electricity to the remaining branches.  3) The total current is equal to the sum of the current from each branch.  4) The total resistance is the reciprocal of the sum of the reciprocals of the separate resistances in parallel.  5) Ohm’s law applies equally to the total circuit or any branch.

CIRCUIT PROTECTION  Circuits are prone to over-currents due to overloads or short circuits.  Fuses and Breakers – Devices that stop the flow of electricity within short circuits or overflows.  Overloads – Too many devices on one circuit.  Short circuits – When two conductors unintentionally touch each other or create a path.

SERVICE PANEL  Where electricity enters the residence.  Contains the hot bar, neutral bar, grounding bar (bonded), and circuit breakers.  Is grounded through grounding rod 8 feet deep or to the cold water piping or both.

GROUNDING  The most important element in wiring. Safety is proper grounding.  Grounding is the connection of all parts of a wiring circuit to ground. This provides protection to persons, the electrical system itself, and the building.  Electrical circuits are grounded by driving a ground rod at least eight feet deep into the earth or connecting to a metallic cold water pipe at least 10 feet in length or a buried ground plate.

AWG  American Wire Gauge – The sizing of the electrical wire.  AWG 10, 12, 14 is used for residential wiring.  AWG 18, 20, 22 is used for our small board jobs.  The larger the number the smaller the wire.

THE IMPORTANCE OF WIRE Wire SIZE  Ampacity – The safe current carrying capacity of the wire.  Voltage Drop – Loss of electrical pressure due to the length or thickness of the wire.

INSULATION COLOR  HOT – Dark colors (Black, Red, Blue)  Brings electricity from the panel to the circuit.  Is always hot.  NEUTRAL – (White, Gray)  Returns power to ground from the loads on the circuit.  SWITCH LEG – Colors other than HOT or NEUTRAL (Yellow)  Supplies power from the switch to its load.  TRAVELER – Same as switch leg.  Pathway from one switch to another switch.  GROUNDING CONDUCTORS – (Bare or Green)  Bonds the boxes and devices to ground.

Breaker Box