Unit 1, Act 1 and 2: Technology Design Process

Unit 3: Residential Electrical Circuits Intro

This unit will introduce you to basic electrical circuits you would find in your home. Common devices such as the receptacle, switch, and lamps installed in common electrical boxes such as the utility, device, and octagon styles will be used. Starting with basic wiring using the right colours, lines, and symbols to design and communicate your electrical circuit through three different types of circuit diagrams.

Getting first hand skills at connecting common devices using cable that is found in the home, learning techniques, and gaining hands-on skills will teach students the basics of home wiring. Making different types of electrical terminations is a critical skill that is important to master to prevent electrical hazards down the road.

Unit Content Activity Quick Links, Click to Jump to Specific Activity!

Unit 3, Act. 1: Electrical Poster, Proper Wire Preparation, and Connections
Unit 3, Act. 2: Connecting Cable, Boxes, and Devices
Unit 3, Act. 3: Residential Wiring Diagrams

Unit 3, Act. 1: Electrical Poster, Proper Wire Preparation, and Connections

Situation:

As a group of students interested in different technologies, one that is used daily is electricity and devices that help each and everyone of us get through our day. Whether it is your alarm clock in the morning, or the refrigerator we use to keep our food cool, the lights that allow us to see in a dark environment, the speakers that allow us to listen to music, the car that would not be if electricity was not there, and of course the electric motors that turn our lives in many different ways.

Problem/Challenge:

Create a letter sized electrical poster that focuses on three aspects, how it works, safety and energy conservation. The poster should have 75% image graphics and 25% of detailed text related to images and poster topics. For the how-it-works part, you may pick any element related to electricity to show how it works. The practical hands-on component students are to successfully prepare wire ends for connecting properly to each other and devices for both solid and stranded connections as outlined in the Create and Construct section.

Investigation/Ideas:

Electrical Theory - How it Works

How electricity works, the theory behind it is important to know, as it is something you can not see, but can be very dangerous if not used properly. The main topics in this handout cover areas such as what electricity is, electron theory, and circuit flow. The following links are some great resources that expand and detail more information about this topic:

Here are some electrical related facts you might find interesting:

When birds land on power lines, they don't get electrocuted because they don't represent a path to ground for the electricity If you had an electrical fire and decided to try and put it out with water, because electricity travels at close to the speed of light, it will travel up the steam of water as if that water was standing still.
Electricity always seeks the easiest and the shortest path to the ground. So if you touch an electrical wire, you become part of the electrical circuit resulting in an instant flow of electricity to the ground
The fuses in your home prevent fires caused by overloaded circuits, but they do not protect you against shock

Electrical Safety

Safety in the home where it comes to anything related to electric, standards must be high for components that use electricity, and if not familiar with the dangers, people can be hurt or worse, die from improper use and/or handling. The following links will detail some safety issues everyone needs to be aware of in the home when using electricity.

There are a lot of safety concerns to be aware of related to electricity. For example, here are some safety points about the use of outlets:

Use only equipment that is properly grounded or double-insulated;
Do not overload outlets;
Do not plug multi-outlet bars to other multi-outlet bars;
Only use equipment that has been approved by a national testing laboratory;
Minimize the use of extension cords. Do not plug two extension cords together;
Do not cover power cords or extension cords with rugs or mats;
Do not run electrical cords through pedestrian aisles;
Unplug or disconnect machines before servicing or repairing;
Do not ignore the warning signs. If an item feels hot, makes an unusual noise (buzz or hum), smokes or sparks, take it out of service immediately and tag it "Do Not Use";
Inspect cords and equipment regularly, and report any defects immediately;
Cover or guard any exposed electrical components or wires;
Unplug cords from the outlet by gripping the plug. Do not pull the cord;
Do not use electrical equipment or appliances near water or wet surfaces;
Never use electrical equipment when hands or the equipment are wet

Electrical Energy Conservation

Safety in the home where it comes to anything related to electricity, standards must be high for components that use electricity, and if not familiar with the dangers, people can be hurt or worse, die from improper use and/or handling. The following links will show some safety issues everyone needs to be aware of in the home when using electricity.

Wire Stripping

Below are some pictures of wire stripping up close. Review the Wire Sizes and Stripping hand-out before attempting what looks like a simple task, but actually has some important points that you need to be aware of prior to completing this task. Look closely at the way the insulation is removed and note the lack of nicks in the cooper wire.

Wires Stripped

Up-Close-Knive & Stripper

Terminal/Rat-tails

Terminal Wire Connection with Shepherd's Loop with Stranded Wire

Making a shepherd's loop with solid wire is considerably easier than stranded wire. The key to making both is to loop it the same direction as the terminal screw goes to tighten it. The following images show how to properly twist stranded wire to ensure when the screw terminal is tightened, the twist of the strand and the direction

Shepherd Loop Step 1

Shepherd Loop Step 2

Shepherd Loop Step 3

Terminal Wire Connection with Shepherd's Loop

When connecting a wired loop connection it is critical that the loop be going in the same direction as the screw terminal is turning. Most screws turn clockwise to tighten so your loop should be also looped around the screw terminal in a clockwise direction. This is done so that when the terminal screw is tightened, the shepherd's loop will be naturally pulled in tighter to the centre of the terminal. If it was looped counter-clock-wise, the tendency would be to widen the loop making it poor connection.

Create/Construct:

Follow the steps below to get started learning about electricity, safety, conservation, and wire joints.

INTRODUCTION: Read the Electrical Theory Handout and answer the questions at the end in the space provided
POSTER: Review the electrical theory resources and then electrical safety in the home, and create a letter sized poster using Illustrator or similar program
Focus on two related themes that show how electricity works and how to safely handle situations and/or devices that use electricity
ACTIVITY: Using 14 AWG solid and stranded demonstrate and complete two 8" lengths of solid wire, 1" stripped with a knife, one with a pair of wire stripper pliers, and also two with stranded wire
One of the 8" lengths for both the solid and stranded will be used to continue making a shepherd's loop on one end, then attaching both to single residential device with two terminals
Once you have created a total of four 8" lengths, two solid wires will be twisted together to make a 2 wire rat tail, the straight end of the solid will be twisted together with the other two stranded wires to create a 3 wire conductor rat tail, both connected by a solderless wire connector size 33 and 35 marret

Evaluation:

Ensure that you have included all required drawing components for full marks.

Evaluation Breakdown Component Descriptions	Marks
Always double check that you have completed all components for full marks.
Electrical Theory- Six review questions answered neatly in sentence form	15
Electrical Poster- Letter size, electricity, safety, & energy savings with 75% images, 25% text	20
Wire Stripped - 4 #14 AWG wires, 8" each, 2 with Knife and 2 with pliers, 1" and no nicks	20
Shepherd's Loop- size, fit, direction of loop and under terminal- stranded/solid	10
Wireless Connector- neatly twisted, tight, no cooper showing, joint solid - stranded/solid	10