#0035: repair and analysis of a talon style folding lock knife

2021-11-03 Otto

#0035: repair and analysis of a talon style folding lock knife

Preamble

I was recently given this folding lock knife to fix for someone. The internal mechanisms of which I found mildly interesting, so I figured it would be worth the time to document it. It may also prove useful for future reference incase I come across something similar.

Initial observations

The first thing that I noticed whilst examining this unit is the unusual blade shape. This is a talon type blade. It is a single edged, crescent shaped blade that curves forwards and terminates in a single point. It’s crescent shape, coupled with the blade edge being on the inner concave curve: give it both a visual as well as function resemblance to the talons of birds of prey. The blade is designed to roughly function in the same way: to pierce and then to hook. This shape of blade can easily convert slashing motions into pierces, due to the blade tip being the leading contact point.

The blade description above may lead you to think that the pictured example knife is a deadly weapon. And that would be the case, at least if not for my second immediate observation. Which is that this knife is a mass produced (I assume) chinese special tacticool toy knife.

It is rather cheaply made, and only really aesthetically resembles the weapon that it is aping. This pictured knife is just a box cutter. That is also it’s literal function currently. Its what the knife’s owner, who is a warehouse operative uses it for. It is also the only thing that it can be used for in my opinion.

Faults

The main thing that was wrong with this unit is that it was not maintained properly. The owner did not tighten the various torx screws on this thing as they worked themselves loose. This led to various joints and mechanisms developing too much play in them. This then resulted in the blade being seated at a crooked angle. Which in turn allowed the blade tip to scratch the handle as it was retracted into it.

Additionally due to the owner’s negligence: some of the various screws that loosened over time, fell out entirely and were consequently lost. This is rather unfortunate, because these fittings consisted of a paired torx screw and socket nut; that where sized to fit flush into the recesses of the handle plates. The socket nut especially is rather annoying to replace. Requiring a specific purchase as it is rather uncommon, and wouldn’t likely be present in any of my bins of miscellaneous salvaged hardware.

The blade itself also has an issue. The main one being that it is made from a miscellaneous soft junk metal; and the second one is that it was currently dull. So it required a basic sharpening, in order to make this knife operable. At least for the relatively short time period that the blade’s soft metal can maintain a serviceable edge.

Parts list

A complete version of this locking knife consists of several discrete components:

1 x camouflage painted outer metal knife handle plate (left)
1 x camouflage painted outer metal knife handle plate (right)
1 x black painted metal inner frame with spring compartment insert gap
1 x black painted metal inner frame with blade locking wedge
1 x black painted metal finger guard with box cutter point
1 x grey painted talon style blade
1 x metal spring
1 x metal spring compartment
2 x plastic washers
4 x smaller black painted metal hex screw and blind nut set
1 x larger black painted metal hex screw and blind nut set
1 x black painted metal trouser clip
3 x black painted hex screws for the trouser clip

Tools and materials

Tools:

Round edge metal file
Knife sharpener rod
Torx screwdrivers (T7, T9)
Tweezers

Materials:

plumber’s grease (or equivalent)

Repair

There really isn’t much to say on the repair itself, as its pretty straight forward. I disassembled then reassembled the knife; fixing everything dodgy about it as I went.

Actions:

Completed knife disassembly.
Bent the blade locking wedge on the inner frame so that it stops the blade from folding closed more reliably.
Greased the blade’s damaged plastic washers to help prevent future wear.
Bent the blade spring’s hook into a right angle in order to get a better hold on the blade.
Re-greased the blade spring within the spring compartment due to presence of dry grease here.
Re-tightened all the screws and socket nuts that keep the housing together.
Added a stand-in replacement for a missing screw and socket nut pair that consists of two screws and a salvaged threaded brass insert nut.
Added a plastic screw and nut to help hold frame. I chose plastic so that I could cut down the screw and round off the nut easily so that it doesn’t snag the user’s hand.
Performed a basic sharpening on the blade using a metal file, then honed the edge using a knife sharpening rod.

The actual repair itself is hardly anything to be proud of. It wasn’t a hard repair and didn’t even take long. However this knife has been saved from going into the rubbish bin, for at least another couple of months, and that should be the main take home. This thing is ready for work again; and should stay that way for quite a while.

Before and After video demo

Before

After

Recommended modifications

1) Grinding the blade edge and sharpening.

The knife blade could use a proper grinding and sharpening: if it to be used for anything more involved than opening boxes. I recommend grinding the blade down so that the angle of the blade edge slopes smoothly up to the mid-ridge. That way the blade can have more acutely angled edge.

This will consequently make the blade sharper than it currently is. A smaller angle will also remain sharper for longer whilst in use, due to the relative thinness of the new blade edge. Even as it dulls. Although the blade will also likely become more brittle and likely to snap as a consequence of the severe loss of material this newly angled edge will require.

2) Installing a blade backstop.

A blade backstop will stop the blade from over-rotating when it is extended. It will also prevent the blade from wobbling when extended by sandwiching it between the backstop and the blade locking wedge.

This knife likely already had a blade backstop of sorts, as it already has the screw holes where on could be mounted. However it was probably lost during use. As it is the blade overextends backwards when it comes in contact with any material that resists it.

3) Thread locker on the screws.

Thread locker such as “Locktite 243” when applied to screws prevents them from slowly working themselves loose during operation, due to factors such as vibration. This will extend the lifespan of this knife when applied to the screws that hold the frames together, as it will mean that they will (largely) no longer need to be checked and re-tightened at intervals.

And since we have already established that this knife’s owner is averse to maintaining his equipment: the lower the level of maintenance this knife needs, will be proportional to the extension of it’s operational lifespan. I.e. it will last as long as it lasts, if the thread locker can keep it together for longer, than it will last a little longer as a consequence.

4) Installation of additional retaining bolts.

I think that installing a few additional bolts and nuts to keep the frame together would greatly increase the overall structural strength of this folding knife. As it would share the strain of keeping the unit together amongst more points. This would allow this knife to be used in applications that require more force.

Although one has to be careful not to drill and install any bolts within the blades seating area within the knife handle housing, or within it’s pathway. Common sense right?

Post mod roles

As it is this knife tool is weak and too dull for any real work beyond cutting the tape off of cardboard boxes. however I theorise that if the above mods are made, then one would end up with a stronger, sharper, and more stable tool.

This would then allow the tool to used in a broader array of applications. For example light wood working, or bush craft applications. A talon style blade is good in both of those applications. The sharp hooked point is good for carving detail into wood. The concave blade is good for gripping and working with rounded objects like natural woods (sticks and branches). For example: for sharpening sticks, or for feathering wood to create tinder. It is also good for harvesting (in this case smaller) plants; as the concave blade helps bundle the stems together when cutting. Like a miniature sickle.

I could go on but I hope you get the point. The issue here is not with the knife’s design, it is with it’s flawed construction. If that could be remedied (or at least alleviated), then this knife could actually become a useful tool. It just requires work to get there.

Closing thoughts

Honestly, I actually rather dislike these types of low-cost low-quality mass produced items. This knife for example: it’s low-cost promotes replacement rather than repair: as it can very quickly make many repairs in it’s owner’s eye deemed as uneconomical. And that is assuming that the owner has a mend-and-make-do mentality to begin with. Most contemporary consumers do not. They have a use and replace mentality.

The main reason why a person may want to repair these things in my mind: is either philosophical (i.e. environmental conscientiousness, fiscal responsibility, anti-consumerist sentiments, etcetera); emotional sentimentality (e.g. hand-me-down from a relative); or if they are in severe financial strife and literally can’t afford to replace a £3.99 work knife.

Now look at it’s cheap build and materials. This factor exacerbates the issue above. Chiefly because it lowers the tools operational lifespan. This is the time it is in use, before it somehow breaks on it’s owner. Hence sooner putting them in a position to make the call on whether or not to either repair or replace the tool.

I do consider a knife like this to have been built with planned obsolescence in mind. Even though the term is hardly used for mechanical hand tools like knives; as it is usually reserved for electronic or computer products.

However, consider this: if the user does no maintenance on this knife. Then there are only so many operational hours that it is capable of before completely falling apart, or at the very least becoming inoperable. It’s shoddy build quality purposefully limits this simple hand tools lifespan. And when it is over, the user is expected to then purchase another one. That is a form of planned obsolescence.

I hate preaching, but please consider not buying this kind of shite. There are better alternatives available. Such as buying second hand quality tools. I always advise that people do the requisite research first. Then spend what they can afford in order to get the best value tools that they can, for their specific use case.

I said “Best value”, not most expensive. A chrome-vanadium spanner is a chrome-vanadium spanner at any price. Just because a person pays more for a brand name, doesn’t necessarily mean that their chrome-vanadium spanner is better than the off brand one.

Nowadays, it’s rather likely that they were both made in the same factory from the same material stock. An idea that would be laughable, if it wasn’t also true. Many brands on the market don’t manufacture anything. They purchase orders from the same OEMs then label the products as their own.

*proceeds to mount high horse.

If you absolutely have to purchase at the bottom of the market because you absolutely have no more money to spend. Then spend time instead. Time upgrading, fortifying, and maintaining your tool. This is so that it can last as long as you need it to. Or at the very least extend the time intervals between new purchases.

That being said, it is an unfortunate reality that most people who do mindlessly purchase bottom of the market products like this knife: are either unable; or more commonly, unwilling to invest time in their tools. They are in many cases content to use the shoddy tool in the short time until it breaks. Then purchase another bottom of the market shoddy tool to replace it with. Repeating this loop of short-sighted wasteful false-economy ad infinitum.

*proceeds to dismount high horse.

I feel that I should somewhat qualify my rather negative sentiments against these types of bottom market products. In the past I have worked within a small recycling facility, one that primarily serviced my local community on behalf of the local council, as well as the surrounding areas. (The point is that we weren’t shipping it’s garbage in.) I worked there as a materials sorter.

It gave me a certain perspective on the sheer volume of material wastage people engaged in. For a supposedly poor community, the amount of waste of useful materials was astounding. Every night I came across hundreds (not hyperbole) of very useable tools of all kinds. Everything from: screwdrivers, knives, drill bits, and spanners, to pots, pans, skillets, as well as whole bicycles some nights. All of that thrown away for recycling.

Many of these things were in decent conditions. Conditions that required either basic maintenance such as: sharpening, some hammering, replacing a handle, or realigning, or even a simple old fashioned cleaning. Gasp! Working there made me dislike a lot of these products; as when I now see them new: I think of where they’ll likely end up in less than a years time … In the fucking trash.

I just don’t like companies purposefully making tools/products that have such a short lifespan designed into them. I doubly don’t like it when these same products are purchased, used, and then wastefully discarded, by people whom I have heard a thousand times: claim poverty. But that’s another rant entirely.

Thank you for listening. It really helps.

Term glossary

OEM – Original Equipment Manufacturer

#0025: Modifying a pair of Game Boy Advance SP earphones into an auxiliary audio dongle

2021-04-202021-05-02 Otto

#0025: Modifying a pair of Game Boy Advance SP earphones into an auxiliary audio dongle

Preamble

This article will consist of a basic tutorial on how to create a Nintendo Game Boy Advance SP (GBA-SP) audio dongle using a broken third party pair of GBA-SP earphones. Additionally I will also provide some related commentary (ramblings) on the similarities between Apple and Nintendo; particularly the way they design their products, and the way that their fanbases receive them. So if you have any old earphones you got as a child and broke yet kept, or maybe even recently purchased as spares and repair? Or if you are inclined to hear me bemoan tribal consumers and corporate avarice. Well here you are.

Creating an audio dongle

The actual conversion is rather simple. You just need to first cut the earphones off; then connect the wires as shown in the pinout and wiring diagram below.

Pinout

Audio jack
1: left speaker positive
2: right speaker positive
3: common ground

GBA-SP port
1: right speaker positive (red wire)
2: closed loop switch
3: (pin absent)
4: left speaker positive (blue wire)
5: common ground
6: closed loop switch

Now that we have the broad methodology of what to do to create an audio dongle, I’d like to talk about a few specifics.

Closed loop switch

In the pinout diagram I labelled pins 2 and 6 as “closed loop switch”. What I mean by this is that there is continuity between these two pins. This means that they are electrically connected to each other. I believe they are configured in this way in order to act as a switch when the plug is inserted into the device.

The electrical connection between the two pins effectively closes an open loop within the device. One that terminates with these pins’ respective sockets. This loop is probably used so that the device can know when an audio peripheral has been connected. This is so that it can act accordingly, by for example switching off it’s built in speaker.

Where to cut the donor earphones cord?

This might seem like a rather simple question at first. However in order to answer it, I needed to answer a few other questions before knowing where exactly I wanted to make the cut. The most important question that needed answering is does the pair of earphones actually work properly, or are they broken somewhere.

Assuming that they have at least one fault somewhere within them, where is the fault? If you can not easily identify it, yet the earphones are still not outputting sound. Then perhaps the fault is hidden. In this case, it will mostly likely be either at the earphones themselves due to snag damage; or if you are unfortunate, it’ll be located near the plug due to something akin to repeated flex damage. Please note that I am just speculating from my experience with repairing headphones.

Once the fault is found, then you must make a decision. Repair the fault, or cut if off (if applicable). In my case the fault was at the left earphone itself. I didn’t probe further than identifying roughly where it was, since I had no intention of repairing something that far down stream. I did however consider whether or not I wanted to retain the inline volume dial. After some consideration I decided to remove it. The reason for this is that I feared that the relatively low quality of the componentry involved; such as the potentiometer, or the PCB and it’s solder joints may actually negatively affect sound quality. So I just snipped it off. Didn’t like it much anyway. It didn’t feel nice to use.

What type of plug or socket to terminate the cord with?

This question was primarily answered by the materials I had available at the time. I did not have an appropriate female 3.5mm audio socket available. However I did have plenty of male 3.5mm jacks on hand; including ones that were corded. In the end I went with a jack that was colour matched (black) and that had the smallest profile.

This male jack enabled me to plug the GBA-SP into an auxiliary port on a sound system should I wish to do so. Additionally when coupled with a female-to-female 3.5mm audio adapter, it enabled me to use headphones or speakers with the dongle. This setup basically gave me the same functionality as having an adapter that terminated in a female 3.5mm socket, paired with a typical male-to-male auxiliary cord.

Soldering the jack

When it comes to soldering audio jacks like these: the first actual thing I did was prepare the heat-shrink tubing for it. Selecting the right sizes and cutting them to length. I prepared two pieces, which I thought was sufficient at the time; however in hindsight I should have prepared three distinct pieces. One to isolate each line.

As it is, it has one to insulate the central shaft from the surrounding ground pad, and one to act as an outer cover; protecting all three wires and acting as a general guard against flex damage for the entire cord. It’s good enough, but it would be better in my opinion if the inner two wires were separated by more than just the enamel coating of the wire strands themselves, as I have left them. A smaller gauge piece of heat-shrink tubing on the inner terminal to cover it’s solder joint would’ve been better.

As for the soldering itself: audio jack terminals like the one pictured can be rather tricky to wire up and solder properly. The reason for this is due to a range of factors. Factors such as: the general fiddliness and fragility of the enamel wires themselves. Although more-so the close proximity of the jack’s terminals to each other, coupled with the convex curve and orientation of their soldering pads, is what adds difficulty; as the awkward angles involved can diminish dexterity.

Additionally, the presence of structural plastic insulation between the terminals, meant that a lower heat and a shorter soldering dwell time was needed. This in order not to damage the jack’s plastics with radiant heat from the work area. Otherwise the plastic will melt and warp the plug’s general shape and structure. All these various factors can make it difficult to solder in a reliable and repeatable manner. However practice and work flow optimisations will mitigate these type of annoyances as one gains experience in this task.

An example in which I optimised the process: was by preparing the wires for soldering by removing their enamel insulation. This is because prior to this: during soldering, the enamel coating on the wires sometimes wouldn’t burn off within the liquid solder blob itself; especially with the necessary (relatively) low heat and short dwell time. When this happened, it resulted in the wire not forming a good electrical connection and/or not bonding physically with it’s solder pad.

I chose to prep the wires by burning off a segment of their enamel coating using a lighter. This had to be done in very quick manner in order to not oxidise the underlying copper strands too much. Burning off the insulation in this manner allows me to quickly solder the wires into place without worrying about any complications from the insulation.

After removing a segment of insulation in this manner, I chose to attach the wires in a way that limited any exposed segments of wire present outside of the solder joint. This is to limit any exposed conductors. Consequently, the solder joints were close to their respective wires’ insulated ends, and only used the exposed segments to get a good electrical connection within the solder joint itself. After-which I’d snip off any excess exposed wire that preceded the joint.

Testing the cable

The attentive readers amongst you probably have noticed that my repair notes contain several resistance tests of the various lines. Most I ran while working on the device, those are the numbers closer to the hand-drawn diagram. Some of which have been struck out. Discount those. The ones of interest are at the bottom of the notes. Those are the results from the post repair test.

The reason for the final test was because I was dubious of the quality of the cables that I was working with. As well as generally dubious of audio cables of this calibre. Specifically, cables that consist of a small collection of loose strands dipped in (I believe) enamel for insulation; then interwoven with additional plastic or nylon strands for strength. They all look and feel fragile and cheap. Having said that however, I should say that a post repair test is a good general practice. Even when confidence in the repair is high.

As you can see the left speaker line has a end-to-end resistance of 10 ohms. Five times that of the right speaker line, and ten times that of the common return (or ground) line. The right and return lines have acceptable resistances in general, and accurate relative resistances to each other. I expected the return common line to have half the resistance due to the doubling of the lines. However, what was unexpected was that the left line was clearly an outlier in line resistance. This in my opinion is due to either the low quality of the cable in general, or a hidden defect I did not find.

It’s not ideal, but upon testing with actual sound, the loss of volume on the left line speaker due to it’s higher line resistance was not noticeable at all. So I just left it be. The effort necessary to track the fault that is adding the 8 ohms to the line, is not worth the reward of having perfectly balanced lines for a GBA-SP’s audio. I used to call it laziness not ploughing down these types of rabbit holes. However as I have aged, I have come to understand the diminishing returns on investments that this type of perfectionism offers.

testing during repair
post repair test

Completed mod demonstration

Related thoughts on Nintendo and their Game Boy Advance SP console

Now that we have created our own DIY audio dongle, let’s talk about why we needed to do this in the first place. In other words, why the Game Boy Advance SP doesn’t have a built-in 3.5mm audio port to begin with. In order to get at this answer, let’s first discuss a completely different technology company and it’s products. As to why, I’ll let you join the dots.

Many people today (2021) credit Apple as one of the most anti-consumer consumer technology companies, specifically with regards to their product design. Although there are numerous examples I could pick out, the one relevant instance here: is the removal of the generic 3.5mm audio jack from their 2016 iPhone 7 models. Anyone who pays any critical attention to this company probably came to a similar conclusion to my own. (Proceeds to pat self on back.) This naturally being that they did so in a bid to to sell first party audio peripherals at a premium. This being to their captive audience of fruity cultists. Cultists that would happily eat that up.

Why am I mentioning this in a Nintendo article? Well it’s because peoples’ memory is generally fickle and often mired with nostalgia; and the residual emotional attachments that it incurs. This leads them to holding double-standards when it comes specifically to childhood brands like Nintendo, often holding them to a lower standard of conduct than brands like Apple. These same people forget that their friend Nintendo did the same thing 13 years prior in 2003 with the incremental release of the Nintendo Game Boy Advance Special (GBA-SP) portable games console.

A games console that had no tangible advantages over it’s Game Boy Advance (GBA) predecessor other than a few quality of life (QoL) improvements. Both consoles played exactly the same games, however the SP boasted: an internal rechargeable lithium-ion battery, and an LCD backlight. For consumers tired of repeatedly buying new AA batteries for their GBA, or always awkwardly angling the unlit LCD towards a light-source whilst avoiding glare; these were improvements worth investment. Those of you who can read between the lines, might’ve guessed that this internal battery naturally required a specific Nintendo battery charger. A theme that they continued in later products such as with the Nintendo Dual Screen portable console (NDS).

However, a more apt feature of criticism in the iteration from the GBA to the GBA-SP, is the removal of the 3.5mm audio jack. Why did they do this you may ask? Well, now I could be wrong, but the cynic in me says that it was to facilitate Nintendo selling official audio peripherals at a premium, to their captive audience of pedantic neck-beards in waiting. That’s us mate.

Laughably, Nintendo’s official response against their audience’s pushback in 2003 was basically the same as Apple’s in 2016. They both said something to the tune of: that the new device simply didn’t have the space for a 3.5mm audio jack. Apple added some device waterproofing claims to this as well. But the core reason was the same: that there’s simply no space for it. Now shut up and buy our official peripherals. Peripherals that use the same port for both audio output and power delivery. So good luck using wired headphones and charging the device at the same time. Enjoy.

To cut it short. My point is that Nintendo has proven themselves to be as anti-consumer as Apple when the mood takes them. However it saddens me that their customers are prone to look at this company through rose tinted spectacles. Often even shouting down valid criticism, yet many within the community still consider themselves distinctly different from the stock of Apple enthusiasts.

That’s what happens when one thinks with their feelings. It’s tribal fanboy-ism at it’s finest. People for whatever reason forget that an individual’s relationship with a company or business like Apple or Nintendo, is strictly transactional. Nothing more. They are not your friends. A corporation does not have the capacity for camaraderie, or loyalty. Only the capacity to take advantage of such feelings in order to sell more to the same people.

Obviously, I am not talking about the entire consumer base here, just the vocal fanatics that seem to dominate public discourse. If anything a logical or reasonable person who likes the products of a particular brand to the point of becoming brand loyal; should ideally, be even more critical (than the average Joe) of their chosen company when it strays into anti-consumer practices. Due to their investment within the brand and it’s products. They likely would wish for them to stay good, more than a person who isn’t all that invested. But that’s not the world we live in. Instead the more invested a person is in a brand, it seems the more likely they are to tribally defend them regardless of circumstance. It’s sad really.

Closing thoughts

I know what you might be thinking, this article is nice and all, but it’s also almost twenty years too late. I mean in previous years getting a hold of an audio dongle for the GBA-SP might have been troublesome or expensive. Back when (the famously litigious) Nintendo were still protective of the console. However in 2021, one could easily purchase a NEW Game Boy Advance SP audio dongle from Ebay for less than a fiver. Since Nintendo doesn’t care much about protecting the rights to peripherals for a console that old (read unprofitable). Sure, the item that you buy won’t be an official Nintendo product, or even a notable third party contemporary brand peripheral, like Competition Pro. But it’ll work. Probably.

To answer that question: Yes, yes you could. You could purchase an unbranded china special peripheral for your almost twenty year old console. Alternatively you could also make use of any old and/or broken first and third party peripherals that you may already have lying around, or even purchased in a mixed joblot or bundle. Essentially converting (basically) e-waste like that into a useful cable. One made to your exact use case and specification no less. Chances are your convert will also be better quality than a bought cable depending on what materials you use to make it.

Mine isn’t, I made mine from a pair of Competition Pro earphones. But still you get my point; I bet if you made yours from a pair of official Nintendo earphones (should you happen to have them), they might be better quality. As for making something for a specific use case: I totally use mine to blast Castlevania: Aria of Sorrow’s soundtrack, via my home sound system. I do it for maximum “immersion” during my midnight gaming sessions. I also want my neighbours to know that I am cool. The banging on the wall seems to indicate that they do.

Thank you for reading.

Links, references, and further reading

https://docpop.org/2016/09/apple-learn-nintendos-headphone-mistake/
https://arstechnica.com/gaming/2016/09/no-headphone-jack-nintendo-did-it-first/
https://en.wikipedia.org/wiki/IPhone_7#Headphone_plug_removal
https://en.wikipedia.org/wiki/Game_Boy_Advance_SP#Headphone_jack

#0004: Dangerous non-compliant BS1363 plug

2020-08-202021-03-14 Otto

#0004: Dangerous non-compliant BS1363 plug

picture of a non-compliant BS1363 plug, with a shrouded earth pin

picture of two BS1363 plugs, one with a shielded earth pin and another without.

Now, I am no electrician. However I’d like to think that I know enough to spot when a consumer device isn’t fit for purpose. In this case its a non-compliant (British Standard) BS1363 plug. Look at the above picture, can you tell which one is potentially dangerous. If you (probably, after looking at the title image) said the one with the shrouded earth terminal, you are correct.

So, what is actually wrong with it?

Well, the earth pin’s base is shrouded; in other words: it is electrically isolated. Why is this a problem? It means that any device that you connect to mains with this cable will not be earthed. Worse yet, an inattentive user (that’s most of us): will very likely think that their device is earthed, and thus conclude that they are safe in the event that the device develops an electrical fault within it. It can’t be serious if it didn’t trip the mains, right?

It is especially nasty in this case, due to the layout of contacts within the female socket for the BS1363 type of plug. You see, unlike the Live and Neutral pins whose female contacts are at the base of the socket; in other words contact and mate with the tips of the plugs pins. The earth pin’s female contact is much closer to the mouth of the socket. Consequently, this means that when the plug is fully inserted, the socket’s contact grips the Earth pin closer to it’s base than it’s tip. Under normal operation, this is to insure that Earth is the first pin to make electrical contact when the plug is inserted, and the last to break electrical contact when the plug is removed from the socket. Its actually really quite a lovely design in my opinion, simple and effective.

Unfortunately, this is exactly what makes this particular plug so egregious. When the plug is fully inserted into the socket, electrical continuity will be broken by the non-compliant plug’s shrouding on the base of it’s Earth pin. But the basic user would think that their device is earthed because the tip of the earth pin is exposed in the same way as the Live and Neutral pins. Its the dangerous subversion of expectations that makes this thing so offensive.

image of a portable oil room heater with a metal chassis — image taken from homedepot.com

Why is earthing devices important?

I’ll answer this with a real world example. Imagine a device, something that demands a lot of current. A high amperage device like a portable room heater with a metal chassis. What if it had been either modified or manufactured to use smaller gauge or lower quality wire (e.g. using aluminium instead of copper), or they skipped adding heat-shield braiding to protect the internal wires from the device’s high residual temperatures. Whatever the case may be.

And due to a combination of carrying a strong current and/or the environmental heat, a wire carrying 250 volts mains melts its plastic sleeving and just touches the metal chassis from the inside of the device. If the device (and consequently the metal chassis) was earthed, then the 250 volts would immediately run down the earth path back to the local RCD (Residual Current Device) switch and trip it. This is because electricity naturally takes the easiest path (or path of least resistance) to earth.

However in the case where the device isn’t earthed; then what’ll happen is that the metal chassis will now be at mains voltage potential. Essentially Live. And odds are that the device in question could still very well function in this state, like normal; making it even harder to notice the fault. If then an unaware user touches the chassis, and in doing so presents a path to earth (usually through their hands, then body, then feet). Well, the electricity is likely to travel through them towards earth, probably killing them in the process. That’s why earthing devices is so important. It provides a very low impedance path for electricity to get to earth, in the case of a fault like the one mentioned above.

close up on a C13/BS4491 and a BS1363 plug showing their power ratings: 10 amp at 250 volt and 13 amps at 250 volts respective

close up on a C13 BS4491 plug showing it's 10 amp at 250 volt rating

Aren’t there any other safety measures in place?

I should note that BS1363 plugs have another safety feature that might save the day in the above example. Namely the replaceable (Live side) fuse within it. In the case of this BS1363 to C13, “kettle” plug. A C13 plug’s maximum rating is for 10 amperes. Logically then, the BS1362 fuse in the BS1363 plug should also be rated at a maximum of 10 amps. That is unless one would prefer that the plug give out before the fuse does, in the case of a surge current exceeding 10 amps (but not 13 amps which is the next category up in the standardised BS1362 fuse ratings).

Notably, the phrase “its not voltage that kills, its current” comes to mind. Although this is strictly not true due to the nature electricity. A high current, low voltage (e.g. a 5 volt 10 amp power-supply) shock is relatively safe, in the same way a low current, high voltage shock (such as static electricity) is relatively safe as well. You need both to be high in order to kill people. To bring it back to the point, we are dealing with 250 volts at or up to 10 amps before the fuse breaks and cuts the power supply. That’s more than enough to seriously electrocute a person. Assuming that it is in fact a 10 amp fuse in that plug. Whose to say that a fuse that came within a non-compliant plug, is itself compliant.

I don’t really want to put too fine a point on it. The inline fuse is just another line in the defence to stop people from accidentally killing themselves. The buildings RCD switches, the plugs fuse, the products internal fuses, and earthing; are all lines in the defence between the person and the power, that have the cumulative effect of making them safe.

Just as a fun thought experiment, imagine if all of these safety features where not present, and you gripped the live chassis, well then in that case: you’d probably be cooking until the power cuts off due to lack of payment of bills. Or rather surge protection outside of the property kicks in, but that’s less fun, and in all likelihood McGrippy would be long dead by then anyway.

picture of a BS1363 to C13 plug (also known as a IEC cord). It's earth pin has been shielded in the same manner as the live and neutral pins.

Where did you even get this thing?

Some background. If I remember correctly, I got the plug along with an unbranded Chinese power-supply from Ebay (or was it Amazon?) a couple of years ago. I took some pictures of it with my dumb-phone (hence the quality images, you’re welcome) due to it’s novelty, but otherwise thought nothing of it. Luckily for one reason or another, I didn’t press it into service.

It was only much later as I progressed in this hobby, did I realise how dangerous it actually was. And after doing some research: I came to the conclusion that one is most most likely to come across these types of sub par electronic equipment from websites like: Amazon, Ebay, Alibaba, Aliexpress, and Banggood. I’m not pointing those particular websites out for any reason, other than their relative dominance of the online market place for consumer grade electronic goods. All ship internationally, and all act more as online market place themselves, then they do actual product vendors. In other words, they aren’t a seller themselves (although some do this too), but have independent sellers operating through their marketplace. Many of these are either drop-ship sellers and straight from factory sellers. Which can sell unbranded and non quality assured dreck; just like this plug.

diagram illustrating the similarities between the C13 and the C17 type plug. The only difference is that C13 has an Earth. — original images taken from wikipedia.org

What should I do if I have one of these plugs?

It largely depends on you, your use-case, the people around you, and your environment. The puritan in me will say cut it and chuck it. It’s not worth the risk of forgetting and accidentally putting it into service in the future. Especially if you store all your extra cables together as I do.

However to avoid turning it into e-waste, you could just chop it up and use it as spares for repairs or projects. Another thing to consider is: if you are hard up for plugs, you could even scrape the shrouding off of the Earth terminal and use it as a normal C14 plug (after testing it of course, I think the earth pin might be too thin to function effectively/reliably/safely after this). Alternatively just use it as a C17 plug, which doesn’t have an earth terminal so the shrouded earth will not matter in the slightest.

One recommendation I would make regardless, it that you clearly mark and label this cable to differentiate it from the others.

Oh, while I am talking about dangerous non-compliant plugs, look at this thing. Shrouded earth, and not even a fuse. Any device that comes with this plug, just has to be hot garbage… and I sincerely hope you aren’t trusting your household’s safety to it.

References / Sources / Further Reading:

https://www.hse.gov.uk/electricity/standards.htm#appliance
https://en.wikipedia.org/wiki/List_of_International_Electrotechnical_Commission_standards
https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets:British_and_related_types#BS_1363_three-pin(rectangular)_plugs_and_sockets
https://en.wikipedia.org/wiki/IEC_60320#C19
https://images.homedepot-static.com/catalog/productImages/1000/5a/5ab2c7d6-d116-4e66-b78e-a38049a7771c_1000.jpg
https://en.wikipedia.org/wiki/Residual-current_device
ElectroBOOM – Which is the Killer, Current or Voltage?[https://www.youtube.com/watch?v=XDf2nhfxVzg]
John Ward – Dangerous Multiway Extension Lead ASTRA BT311 (Part 2) [https://www.youtube.com/watch?v=C1h9LLJJvk0]
John Ward – MK Socket Outlet BS1363 Dismantled & Examined [https://www.youtube.com/watch?v=H1gMYu5VHus]
ElectroBOOM – The Outlet that Saves Lives [https://www.youtube.com/watch?v=GlM6PE2kKVY]
ElectroBOOM – 7 MILLION VOLT TASER (stun… thingy)!!! [https://www.youtube.com/watch?v=DOMs7mYm_zs]
https://hackaday.com/2016/05/19/hackadays-fun-with-international-mains-plugs-and-sockets/
https://hackaday.com/2016/05/11/looking-mains-voltage-in-the-eye-and-surviving-part-1/