How to Wire a Plug (& Test it!)

We’ve mentioned on the blog before that we’re really keen on exposing our students not only to coding but to technology more broadly. In particular we want our classes to be full of activities that few if any of our students will have tried before.

One of those activities is wiring a plug. This lesson made the cut for a couple of reasons. For parents, hearing that their 8/10/12-year-old child has learned how to wire a plug is really cool. Lots of adults can’t do that confidently, let alone primary school kids!

For the students, it’s always good fun to get a break from the screen to do something hands on. Even better when the lesson starts with warnings about not electrocuting yourself or cutting off your fingers. What 10-year-old doesn’t get a little excited at that?!

Test boxes - do YOU know how to wire a plug??

Test boxes - do YOU know how to wire a plug??

As tutors, we like lessons which have real-life applicability, and we really like lessons that make kids sit up and pay attention. We’ve structured our lesson with safety as a top priority, and part of that is starting the lesson by talking about the destructive power of electricity. Speaking from experience, shock and awe is a great way to demand a class’ attention!

It’s also great to be able to hand over tools which, while not that dangerous, do demand a certain amount of care. In our experience students will rise or fall to the level of our expectations of them, and the best thing we can do as educators is to let them know we expect a whole lot from them.

There was also a lot of care put into the design of our tester boxes, pictured above. The cables the students will be stripping and re-wiring a plug to have a 3-pin male connector on the other end. The test boxes also have a 3-pin male connector, along with the standard socket. To finish the circuit students need the “key”, a 3-pin female-to-female cable carried by the tutors (pictured below). This, along with our low student:teacher ratios, helps ensure that it would be nearly impossibly to connect the test box to mains power and complete the circuit, even if you did somehow manage to get out from under the watchful eye of our tutors!

The full circuit

The full circuit

The teacher’s “key”

The teacher’s “key”

As for the boxes themselves, the idea is very simple. Inside the boxes are large 6-volt batteries, the three visible LEDs and buttons, and a resistor. When the circuit is complete with the newly wired plug and the teacher “key”, each wire can be tested independently. If everything has been done correctly the blue button should light the blue LED, and so on. If for example the blue and green/yellow wires have been mixed up, then the blue button will light the green LED, and vice versa. Finally if a wire hasn’t been connected properly at all then the LED will simply not light at all.

(We owe a big thanks to Eoin Sweeney of epms.ie for his work on assembling the test boxes and ensuring they are safe for student use. His bread and butter is doing CCTV and alarm systems, but it seems there’s plenty else he can turn his hand to as well. Thanks Eoin!)