How To Design A Custom Generator Interlock Plate

If you connect a generator to your home’s main electrical panel when the power goes out, you need to make sure the main breaker is shut off. Otherwise, when the power comes back on, you (or the linemen) are going to have a bad time. There are commercial interlock plates which physically prevent the generator and main breakers from being switched on at the same time, but since they tend to be expensive, [HowToLou] decided to make one himself.

The hardest part of this project is designing the template. It needs to be carefully shaped so its resting position prevents the generator’s breaker from being switched on under normal circumstances, but once the main is turned off and out of the way, you should be able to lift it up and have the clearance to flip the lower breaker. Spending some quality time at the breaker box with tape and a few pieces of cardboard is going to be the easiest way of finding the proper shape.

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How Does A Circuit Breaker Break?

Even if you aren’t an electronics person, you probably have a working knowledge of circuit breakers. When the lights go out, you find the circuit breaker and flip it back to the on position. Most people understand, too, that the breaker will trip if you overload the circuit with too many things plugged in or with an accidental short circuit. But how does this common device actually work? Keep in mind, circuit breakers need to be super reliable and have been around long enough that you can imagine they are pretty low tech. [Learn Engineering] has a very clear video about what goes on inside a circuit breaker that’s worth the eight minutes to watch. You can see the video below.

The handle is a mechanical engineering marvel, using two springs and a special design so that even a tiny force will cause it to snap to the off position. That takes care of a human tripping it. However, you have two other cases where you want to turn it off: overload and short circuit.

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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.
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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!

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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.

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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!


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