#0004: Dangerous non-compliant BS1363 plug

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.

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.

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.

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.

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/