it's fair to say that the world that we live in has gone through some amazing technological
changes over the last 70 years or so computers once filled an entire room in 1943 the president
of IBM confidently predicted that there was a world market for perhaps as many as five computers
i'll be using at least four of those to make this video we now live in a world where most people
in developed countries will have a computer in their pockets more powerful than the ones used to
put humans on the moon and what do we use it for looking at pictures of cats and what our friends
are having for dinner probably through a cracked screen so against this backdrop of constant change
and development it's fair to say that if an object has endured through it all then it must
be a pretty awesome piece of design so i submit to you the greatest unsung hero of the electrical
industry the 13 amp plug top conforming to BS1363 it's probably not something you've given
a lot of thought to over your electrical career as they are just so ubiquitous we probably come into
contact and operate one of these every single day of our professional and personal lives but i think
it deserves a second look because i think this is one of the best designed and most enduring objects
that exists in the electrical industry since 1947 it's gone through some changes and slight
improvements but remains pretty much as it was back all those decades ago surviving wars changes
in government and even the adoption of the metric system so why do i love this design so much well
let's take this Permaplug from BG as an example this device solves the problem of how to make and
break contact with a potentially lethal force in a safe manner and it does it in a number of ways
first of all you've got the consistent position of the pins relative to each
other this means that you could take this brand new plug manufactured in this decade
and use it on a socket outlet manufactured in 1947 and it will operate flawlessly in fact i
think there might be a few of those still in my nun's house but it's true isn't it
you never find yourself bringing home a brand new appliance and wondering if it's going to
connect to your socket outlets or wondering if you'll have a plug that will fit it always fits
then there's the length of the pins themselves down here you've got the live connections you've
got the line in neutral and then at the top there's the pin that gives you the connection to
earth so these two are dangerous this one can make your appliance safer now looking at the length of
them you can see that the earth pin is slightly longer than the live pins to understand why we
need to look at the socket that this will connect to which i've got an example of just here now this
is a mobile socket outlet that's connected to the end of a BG extension lead and if we have
a look inside here you can see that the terminals inside the socket are covered up by these covers
or shutters that means that i can't get say my screwdriver in there and receive a nasty shock
but we still need to get past those shutters to connect our plug so because the earth pin
is a little bit longer than the live pins it's used to open up those shutters and make contact
now the writers of bs 1363 could have decided to use the line or neutral pin to do that
but their wisdom shines through because the safety connection gets made before the live connections
and that makes your appliance potentially more safe now it's quite hard to see that in action
from here so if i just take this one and turn it around you can see the action taking place
there goes the earth pin as i plug that in there you can see that it actually opens the shutters up
and allows the line and neutral pins to make their contact however before we send this all
the way home let's look at another great feature of this overlook classic which is right here
in the gap between the plug and socket notice that the pins there the live pins are sleeved
meaning that the live pins can make contact with the live parts of the socket and yet no live part
is then accessible to the operator now whenever i see a sleeved pin on a plug it gives me a wry
smile because it wasn't until 1984 that bs 1363 required that these pins be sleeved now i'm a
bit ashamed of this as an electrician but when i was a young lad i can't remember exactly how
old hopefully before i started my apprenticeship i had a lamp in my bedroom with an old unsleeved
plugged up on it and i think the plastic on the plug was a little bit damaged because it got
jammed in the socket and only came out about halfway pretty much exactly like it is there
now the good news is that i decided before going any further to switch the lamp off at the socket
then i decided to get a pen knife which definitely didn't have a metal handle
and pushed it between the plug and socket to try and leave it out unfortunately the
blade of the metal handled knife connected the unsleeved line and earth pin of the still very
live plug-in socket resulting in rather a loud discharge of energy and also my digestive system
needless to say i needed a new pen knife and a change of underwear so i am extremely grateful
that my own stupidity is now covered along with the live pins on the plug top but you know there's
even more here than what we've discussed the pins are chamfered to make insertion more easy but that
then creates an engineering challenge because the socket terminals as you can see here have to grip
the pins tightly enough to make a good electrical connection but not so tightly that it makes it
difficult to withdraw so they're made with a certain amount of springiness to facilitate that
but if these chamfers on here are made too long it can cause the plug to be literally
ejected from the socket during use so designers actually have quite a small amount of material
to make a good connection with now we haven't even looked at the inside yet we could talk about maybe
the interchangeability of the fuses we could talk about the cord grip for cable retention i've never
been able to establish if it was intentional that the round conductor goes to the right and
the blue to the left because you've got the second letter of each colour as a guide if that's just a
glorious coincidence maybe someone watching could enlighten me maybe there's a nice feature on here
that you know of that i've missed or maybe there's an electrical device that you think
is an overlooked design classic that you'd like the less handsome intelligent and witty younger
brother of richard osmond to make a video on then please leave it in the comments below and we'll
see what we can do so in an ever-changing world of devices and gadgets it's nice to know that the
bs 1363 plug like the perma plug from bg has stood the test of time thank you very much for watching
you