Science Through Engineering Concepts summer course
Electricity
Day 1
Activity
Give construction examples
Concept
Application overview
Material
Pile o’ electrical stuff
Pedagogy – Similar to Thermo, we’ll do a quick basic science overview first, then
construction applications
Battery & bulbs
Basic circuit
batt. & bulb supplies
Diagram circuit
Discuss basic circuit & components & diagrams
Series & parallel circuits
Series & parallel
batt. & bulb supplies
Diagram circuit
Basic voltage, current, resistance lecture
Series & parallel dogs
Series & parallel
Basic electrical safety
Blue switches w/ batt & bulbs
hot dogs & nails
hot dogs & nails
switches and shorts
blue switches
Diagram & discuss switch & shorts
Wire in a breaker
Breakers (safety & “switch”)
Wire a socket w/switch
bulb
App. of basic circ.
p.s., cord, outl., sok,
Diagram circuit
Discuss power source
Wire a switch for outlet
App. of switches and shorts real light switches
2 outlets + socket , 1 outlet w/ sw
parallel wiring
2nd outlet
Diagram & discuss parallel wiring
Volts & amps
Volts & amps in parallel
Discuss circuit overloading & breakers
Padagogical aside - theory <-> application
multimeters
Day 2
Mix & Match – demonstrate high voltage through little wires & battery to power outlets
and big wires to light small bulbs
Grounding activity (Larry)
Discuss physics of grounding
GFCI
Breakers
GFCI vs breakers
2-way switches
2-way switches
Diagram
3-way switches
3-way switches
Diagram
Pedagogical – Series switches vs. series resistors
***Go home and write down any applications of what we learned or electrical
questions you have about your house or any others
Day 3
Go over participant questions and applications
Dimmer switches – at least 3 possible ways, can you think of ‘em?
Dimmer switches – how they really work, frequency issues
Dimmer switch
Incandescent v. halogen v. gas vapor (gas discharge) (neon, mercury, sodium vapor) v.
fluorescent v. LED
Lm/W
Candle
0.3
0.05%
40W tungsten
13
2%
100W Tungsten
17
Halogen
16-26
2-4%
Fluorescent
45-60
7-10%
LED
10-75
2-10%
Sodium vapor
45-183 (90-125)
7-27 (13-18)%
Theoretical 100%
683
If Time
Power generation, 60 Hz AC
Gencons
Line loss (incl. wire overheating, V vs. A trade-off)
thin wire, multimeters
Line loss revisited, including transformers to houses
Advanced safety (lightning rods, safety data, GFCI, ground, breakers (incl. series) &
fuses, human resistance
human R demo stuff
240 v. 120 (safety, V vs. A trade-off, also mention)
Alternative power
On grid v. off-grid, power storage
Wind & water
Solar
Transfer Task
Flashlights – 1 or 3 batteries – (optional - switch should still work)
Problems to solve
Switch for 1st outlet, 2nd always on
2-way switches
3-way switches
Flashlights
switches in series situations
circuit components & app.
2-way switches
3-way switches
Flashlights, bike light
Demos & discussions
Ground in building
long wire
Line loss (incl. wire overheating, V vs. A trade-off)
thin wire, multimeters
Advanced safety (lightning rods, safety data, GFCI, ground, breakers (incl. series) &
fuses, human resistance
human R demo stuff
240 v. 120 (safety, V vs. A trade-off, also mention)
Advanced concepts
Dimmer switches – at least 3 possible ways, can you think of ‘em?
Dimmer switches – how they really work, frequency issues
Dimmer switch
Line loss revisited, including transformers to houses
GFCI
GFCI outlets
Wiring GFCI in series
DC v. AC, 50 v. 60 Hz
Breakers – 3 types bimetallic, electromagnetic, electronic
Incandescent v. halogen v. gas vapor (gas discharge) (neon, mercury, sodium vapor) v.
fluorescent v. LED
Lm/W
Candle
0.3
0.05%
40W tungsten
13
2%
100W Tungsten
17
Halogen
16-26
2-4%
Fluorescent
45-60
7-10%
LED
10-75
2-10%
Sodium vapor
45-183 (90-125)
7-27 (13-18)%
Theoretical 100%
683
Alternative power
On grid v. off-grid, power storage
Wind & water
Solar
Eliminated Ideas (from original plan)
Have participants extract key science knowledge from each activity
Longer battery and bulbs activity
Participants build an electricity unit
Construction applications
Wiring
Breaker boxes (http://science.howstuffworks.com/circuit-breaker1.htm)
Outlets
Lights
Switches 1-way, 2-way, 3-way, dimmer
Grounding
240 v. 120
Appliances
Overloading
Shorts and open circuits
Line loss & wires over heating
Safety
Dimmer switches (http://home.howstuffworks.com/dimmer-switch2.htm)
Lightning rods
GFCI (http://hyperphysics.phy-astr.gsu.edu/hbase/electric/gfi2.html)
Activities
Materials
Basics for many activities
20 Grounded cords, cut at end
6 Power Strips
6 individual breakers
Planned
Wiring regular outlet
Wiring regular switch and light
Broken flashlights
Hotdogs
What’s connected to ground?
Line loss
Wiring GFCI outlets in series
2-way switch problem
3-way switch problem
Dimmer switch
Light fixture base
Other Ideas
Human resistance
26 outlets
12 sockets
12 bulbs
20 switches,
20 flashlights
1 pack nails, 1 pack hotdogs
Long wire
1 Long-thin wire
1 Multimeter
20 GFCI outlets
40 2-way switches
20 3-way switches
6 dimmer switch(es)
6 light fixture bases
6 more outlets for series
Power pack, sensitive multimeter
The U.S. Home Product Report, Appliances and Equipment
John R. Hall, Jr., November 2005
Cost: $25.00. 164 pages. Order # USS19.
Abstract: In 1999-2002, there were an estimated 32,000 reported home structure fires per
year associated with electrical distribution equipment. Fixed wiring, switches, receptacles
and outlets account for the largest share of fires among major types of electrical
distribution equipment, while cords and plugs account for the largest share of civilian fire
deaths and injuries. Short circuit or ground fault is the leading factor contributing to
ignition in every group of electrical distribution equipment products. Clothes dryers and
washing machines are the leading equipment involved in home fires, excluding heating,
cooking and electrical distribution equipment.
This report addresses all types of equipment-related home fires not covered in NFPA's annual reports on
home heating and home cooking fires. It addresses the sizes of these fire problems (fires, deaths, injuries,
dollar losses) by type of equipment, patterns of human error or mechanical or electrical failure that cause the
fires, what materials are ignited, and safety tips. The report also provides year by year statistics for homes,
non-homes, and all structure fires combined.
Michael McCann
Statistics clearly show that exposure to electricity is still a major cause of deaths among construction
workers. Among electricians, the most serious concern is working “live” or near live wires, instead of deenergizing and using lockout/tagout procedures. Among non-electricians, failure to avoid live overhead
power lines and an apparent lack of basic electrical safety knowledge are the major concerns.
Electrocutions are the fourth leading cause of death among construction workers in the United States. An
average of 143 construction workers are killed each year by contact with electricity (based on government
data for 12 years, 1992 through 2003). Electrical workers had the most electrocutions per year, followed by
construction laborers, carpenters, supervisors of non-electrical workers, and roofers (chart 1). (These
numbers do not reflect the risk for each trade, because no corresponding information is available on hours
worked for each trade.)
1. Electrocution deaths in construction, by trade, United States, 1992-2003
Trade
# deaths
% of total
Electrical workers
586
34%
Construction laborers
274
16%
Carpenters
97
6%
Non-electrical supervisors
86
5%
Roofers
72
4%
Other trades
600
35%
Total
1,715
100%
Note: A total of 1,715 deaths in 12 years. Electrical workers includes electricians and their apprentices,
electrical helpers, electrical power installers and repairers, and their supervisors. “Other trades” include
apprentices and their helpers.