Ham Radio Trips Circuit Breakers

Arc-fault circuit breakers are a boon for household electrical safety. The garden-variety home electrical fire is usually started by the heat coming from a faulty wire arcing over. But as any radio enthusiast knows, sparks also give off broadband radio noise. Arc-fault circuit interrupters (AFCI) are special circuit breakers that listen for this noise in the power line and trip when they hear it. The problem is that they can be so sensitive that they cut out needlessly. Check out the amusing video below the break.

Our friend [Martin] moved into a new house, and discovered that he could flip the breakers by transmitting on the 20-meter band. “All the lights in the place went out and my rig switched over to battery. I thought it was strange as I was certainly drawing less than 20 A. I reset the breakers and keyed up again. I reset the breakers again and did a [expletive] Google search.” Continue reading “Ham Radio Trips Circuit Breakers”

Awesome Prank or Circuit-Breaker Tester?

Many tools can be used either for good or for evil — it just depends on the person flipping the switch. (And their current level of mischievousness.) We’re giving [Callan] the benefit of the doubt here and assuming that he built his remote-controlled Residual Current Device (RDC) tripper for the purpose of testing the safety of the wiring in his own home. On the other hand, he does mention using it to shut off all the power in his house during an “unrelated countdown at a party”. See? Good and evil.

An RCD (or GFCI in the States) is a kind of circuit breaker that trips when the amount of current in the hot and neutral mains power lines aren’t equal and opposite, which would suggest that the juice was leaking out somewhere, hopefully not through someone. They only take a few milliamps of imbalance to blow so that nobody gets hurt. Making a device to test an RCD is easy; a resistor between hot and the protective ground circuit would do.

[Callan] over-engineers. He used a 50 W resistor where 30 W would do under the worst circumstances. A stealthy solid-state relay switches the resistor in, driven by an Uno and a Bluetooth module, so he can trip his circuit breakers from his smartphone, naturally.
Continue reading “Awesome Prank or Circuit-Breaker Tester?”

Tripping Out: A Field Guide to Circuit Protection

My introduction to circuit protection came at the tender age of eight. Being a curious lad with an inventive – and apparently self-destructive – bent, I decided to make my mother a lamp. I put a hose clamp around the base of a small light bulb, stripped the insulation off an old extension cord, and jammed both ends of the wires under the clamp. When I plugged my invention into an outlet in the den, I saw the insulation flash off the cord just before the whole house went dark. Somehow the circuit breaker on the branch circuit failed and I tripped the main breaker on a 200 amp panel. My mother has never been anywhere near as impressed with this feat as I was, especially now that I know a little bit more about how electricity works and how close to I came to being a Darwin Award laureate.

To help you avoid a similar fate, I’d like to take you on a trip (tee-hee!) through the typical household power panel and look at some of the devices that stand at the ready every day, waiting for a chance to save us from ourselves. As a North American, I’ll be focusing on the residential power system standards most common around here. And although there is a lot of technology that’s designed to keep you safe as a last resort, the electricity in your wall can still kill you. Don’t become casual with mains current!

Continue reading “Tripping Out: A Field Guide to Circuit Protection”

Inside A Circuit Breaker With MikesElectricStuff

High voltage is  not something we usually tinker with at home. In fact, most of us are more comfortable working with non-lethal, low current, low voltage DC signals. When we do venture into the world of high voltage, we prefer to do it vicariously thru someone with more safety training and/or experience.

[Mike] shows us the inner workings of a 240VAC circuit breaker and explains how the different safety features in the device work. In proper MikesElectricStuff form, [Mike] finds out what it takes to destroy the device. Or in this case multiple devices, [Mike] uses his “Destruct-o-tron” to create catastrophic failure in more than one breaker. You can check out the video embedded after the break to learn a bit about how a circuit breaker works, and of course witness the carnage.

Continue reading “Inside A Circuit Breaker With MikesElectricStuff”

We Have a Problem: Household Electrical

Hackaday, we have a problem. The electricity in your house is on. It’s always on. How fast are those kilowatt-hours ticking by and what is causing it? For most people the only measurement they have of this is the meter itself (which nobody looks at), and the electric bill (which few people actually analyze). Is it silly that people pay far more attention to the battery usage on their phone than the electricity consumption in their abode? I think it is, and so appears another great seed idea for Hackaday Prize entries.

A Better Way to Measure

breaker-panelThe tough part of the problem here is getting at reliable data. Just yesterday we saw an incredible resource monitoring project that uses an optical sensor to measure the turning or the wheel in an electric meter. We’ve seen similar projects for meters that have a blinking LED, and a few other methods. But in many cases the electrical meter is outdoors which makes cheap, easily installed sensors a difficult goal to achieve. Even if we did, this still provides just one stream of data, the entire house.

Alternatively you could tap into the breaker box. We’ve seen [Bill Porter] do just that and there are some commercially available kits that include an octopus of clamp-style current sensors. This is a bit of an improvement, but still requires the user to open the electrical panel (don’t scoff at that statement, you know most people shouldn’t be doing that) to install them. I’m sure there are other methods that I’m missing and would love to hear about them in the comments below.

The Point

To sum up what I’m getting at here, think about the Kill-A-Watt which proved to be a very interesting hack. People liked not just seeing how much power something uses but extending where that data can be accessed. We don’t remember seeing any successful efforts to move the concept ahead a few generations. But if someone can crack that nut it could yield a wave of energy savings as people are able to be better connected with what is using a lot of electricity in their homes.

Your Turn (and Lessons from Last Week)

As with last week, now it’s your turn to come up with some ideas… wild, fantastic, good, bad, outlandish, let’s hear them. Better yet, document your idea on Hackaday.io and tag it with “2015HackadayPrize“. You can win prizes just for a well presented idea!

Speaking of last week, I shared the idea of adding some feedback to how long you’ve been in the shower. There were many opinions about the value and worthiness of that idea so I thought I’d close by covering some of them. Yes, there are much bigger wastes of water (and electricity in this case) in the world but why limit our solutions to only the largest offenders? The low-hanging fruit tends to be stuff a lot of people can understand and relate to. If we only talked about large-scale fixes (I dunno; reducing mercury emissions from power plants?) there is little momentum to crank-start a movement. If you found yourself thinking the ideas from this week and last are far too simple to win The Hackaday Prize that means you better get your project going. The world is hacked together by those who show up.

I’d love to hear suggestions for future installments of We have a problem. Leave those ideas in the comments and we’ll see you here next week!

The 2015 Hackaday Prize is sponsored by:

William Kamkwamba talks windmills with Jon Stewart


Last night [Jon Stewart] interviewed [William Kamkwamba] on The Daily Show. [William] is the young man from Malawi who at the age of 14 built a windmill generator out of discarded items. Now at 22 years old, [William] is working on his SAT scores in hopes that he can attend college in the US. We get a bit more insight about him and his build as he promotes his new book.

[William] was 14 when he completed the three month long build of his generator. He had previously dropped out of school because “my country was experiencing some famine”. The only resource he had at his disposal was a library that is funded by the US government (sounds like that turned out to be a good investment!).

After seeing a photograph of a windmill he was driven to succeed by the mantra: “somewhere somebody did it, it didn’t fall from the sky”. He goes on to explain how he built a circuit breaker (pictured above) to prevent a short circuit from burning his house down. Two nails are wrapped in wire with a magnet in the middle. If there is a short circuit, one of the nails will repel the magnet while the other attracts it. The nail is connect to a switch and when it moves to one side the switch is opened, breaking the circuit. Upon hearing this, [Stewart] makes the obvious comparison between [Macgyver] and [Kamkwamba].

One of the most endearing points in the interview is a story [William] shares about his first experience with the Internet. He was invited to the TED conference in 2007 and someone asked him if he’d used the Internet. Of course he hadn’t and they then started talking about using Google. When the search engine was explained to him he suggested that “windmill” be entered as a query. When millions of hits were returned his revelation was “Where was this Google all this time?”.

This is an amazing story that we can’t get enough of here at Hack a Day. Make sure you don’t miss the interview which starts 12:25 into the episode.