Source: https://mokxi.com/teachers/plans/how-a-house-is-wired Updated: 2026-11-11 Lesson plan # How a house is wired lesson plan From the service and the meter to the panel, branch circuits, hot neutral and ground, three-way and four-way switches and GFCIs, all on low-voltage models you can break safely. 5 chapters, 8 lessons, about 6 hours, no board. Every lesson runs in the browser, with nothing to install. Start a class from this course The unit ## Objectives and materials ### By the end, students can - Two legs and a neutral, and the meter that counts every watt hour. - Breakers, branch circuits and the three wires every circuit runs. - Switch loops, three-ways and four-ways, with every flip checked. - What an outlet carries and how a GFCI senses a leak. - A whole room on one breaker: overload it, then fix it. ### Materials for the whole unit - AC voltage sensor, ZMPT101B - Arduino Uno R3 - Bench power supply x 4 - Character LCD with I2C backpack - Current sensor, ACS712 x 4 - DC jack and adapter - Filament lamp x 3 - Full-size breadboard - Half breadboard x 4 - LED - Mains transformer, 230 V or 120 V to 12 V - Multimeter x 2 - Pushbutton x 2 - Relay module - Resistor x 9 - RGB LED x 4 - Signal generator - Slide switch x 3 Every part is already on the simulator’s bench, so there is nothing to buy or hand out. The counts are the most any one lesson uses, if you build it on real breadboards too. Chapter 1. About 1 h 30 min ## Where the power comes in Two legs and a neutral, and the meter that counts every watt hour. Lesson | Time | What students do The service: two legs and a neutral How the power company feeds a North American house, on a one-tenth scale model: two legs and a neutral from a center-tapped transformer, 120 and 240 from the same wires, and why a lost neutral makes lights flare. | 40 min - Run the service - Leg to leg - The neutral carries the difference - Quiz: lose the neutral - What you just saw, and who does it The meter: watts and watt hours What the meter on the side of a house counts: volts times amps is watts, watts times hours is energy, and the bill is in kilowatt hours. A real energy monitor sketch on a scaled AC sensor. | 50 min - Run the monitor - Watts are volts times amps - Make it a US house - Watt hours add up - Quiz: predict the volts - Who owns the meter ### Materials - AC voltage sensor, ZMPT101B - Arduino Uno R3 - Character LCD with I2C backpack - Current sensor, ACS712 - Filament lamp x 3 - Mains transformer, 230 V or 120 V to 12 V - Multimeter x 2 - Resistor - Signal generator - Slide switch ### Check for understanding Each student finishes "The meter: watts and watt hours" on their own, without opening the hints. The simulator checks 6 of its 6 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Who owns the meter". Chapter 2. About 1 h 30 min ## The panel and its circuits Breakers, branch circuits and the three wires every circuit runs. Lesson | Time | What students do The panel and its branch circuits A main panel splits the service into branch circuits, each behind its own breaker. A load monitor on four stand-in circuits shows breaker ratings, the 80 percent line for continuous loads, overloads and balancing the two legs. | 50 min - Four branch circuits - All green - Past 80 percent - Overload - Balance the legs - Quiz: predict the total Hot, neutral and ground Three wires with three jobs: the hot brings the push, the neutral brings the current home, and the ground is there only for a fault. A 12 V lamp with a metal case shows what the ground wire saves you from. | 40 min - Three wires, three jobs - A fault with the ground in place - The same fault with no ground - Quiz: wet hands - Bonded at one place ### Materials - Arduino Uno R3 - Bench power supply x 4 - Current sensor, ACS712 x 4 - Filament lamp - Full-size breadboard - Half breadboard x 4 - LED - Multimeter - Resistor x 9 - RGB LED x 4 - Slide switch x 3 ### Check for understanding Each student finishes "Hot, neutral and ground" on their own, without opening the hints. The simulator checks 5 of its 5 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Bonded at one place". Chapter 3. About 1 h 15 min ## Switching lights Switch loops, three-ways and four-ways, with every flip checked. Lesson | Time | What students do Switch loops and three-way switches A switch goes in the hot, never the neutral. Then one light from two places: two SPDT switches joined by travelers, on a 12 V model, with every flip checked. | 35 min - Switch the hot - Flip the switch by the door - Quiz: now the far switch - The truth table Four-way switches: three places, one light A long hall or a stair needs a light from three places: a four-way switch between the two three-ways swaps the travelers. Modeled as parity on an Uno with three slide switches. | 40 min - Run the model - The far end - Quiz: the middle switch - Read the truth table - In the wall ### Materials - Arduino Uno R3 - Full-size breadboard - Half breadboard - LED - Resistor - Slide switch x 3 ### Check for understanding Each student finishes "Four-way switches: three places, one light" on their own, without opening the hints. The simulator checks 5 of its 5 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "In the wall". Chapter 4. About 55 min ## Receptacles and GFCI What an outlet carries and how a GFCI senses a leak. Lesson | Time | What students do Receptacles and GFCI protection An outlet's hot, neutral and ground, and the idea inside a GFCI: compare the current going out with the current coming back, and trip on the difference. A clearly labeled teaching model, not a real GFCI. | 55 min - Read the banner - Balanced: out equals back - A leak - RESET refuses while the leak is there - Clear it and reset - Quiz: what does TEST do? - Where GFCIs go ### Materials - Arduino Uno R3 - Current sensor, ACS712 x 2 - DC jack and adapter - Filament lamp - Half breadboard - Pushbutton x 2 - Relay module - Resistor - Slide switch ### Check for understanding Each student finishes "Receptacles and GFCI protection" on their own, without opening the hints. The simulator checks 7 of its 7 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Where GFCIs go". Chapter 5. About 50 min ## Boss project A whole room on one breaker: overload it, then fix it. Lesson | Time | What students do Boss: wire a model room One room on one breaker: a ceiling light on a three-way pair, a desk lamp and a space heater on the outlets, and a meter on the main. Overload it, then fix the room so everything runs. | 50 min - Walk into the room - Lights out from the door - Back on from the bed - Quiz: plug in the heater - Fix the room - Make it yours ### Materials - Bench power supply - Filament lamp x 2 - Multimeter - Resistor - Slide switch x 3 ### Check for understanding Each student finishes "Boss: wire a model room" on their own, without opening the hints. The simulator checks 6 of its 6 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Make it yours". Your class ## Teach this unit as a class Start a class from this course and its 8 lessons are assigned in one go, in order. Students join with a six-character code or printed login cards, and each one’s work comes back to you. The class tools are free for 30 days for one class of up to 20 students, with no card. The lessons themselves are free either way. 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