Author Topic: [YouTube]: American is impressed by sensible British mains plug design  (Read 14863 times)

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Offline IanB

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #100 on: October 23, 2022, 03:56:36 pm »
What are the holes in the US prongs for? Are they for ball bearings to drop in and retain the plug? I presume they're not so some kid can bolt some wires to them...

If they are part of a retaining mechanism, shouldn't that mitigate against them falling out of the socket, but still allow them to pop out if the cable is snagged?

A long time ago, receptacles were made with a protruding nub on the spring that latched into the hole and made the plug more secure. But things changed and receptacles today are made with much stronger spring force and no longer need that feature. However, plugs are still made with the holes in the prongs, just in case they get plugged into one of the older receptacles that was made with the locking nubs inside it.
 
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Online PlainName

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #101 on: October 23, 2022, 04:09:59 pm »
Thanks :)
 

Offline IanB

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Re: [YouTube]; American is impressed by sensible British mains plug design
« Reply #102 on: October 23, 2022, 04:13:15 pm »
There have long been some niche products like that. You made it sounds like bayonet lamps are safe. The vast majority are not.

To be practical about it, if you poke your finger inside a bayonet socket while it is switched on, the most likely outcome is that your finger will contact both pins at the same time. So the result will be that your finger gets zapped, which while painful, is not dangerous. Realistically, the probability of receiving a shock current that goes through your heart is low.

We can also observe that every child over the age of 4 or so knows not to poke fingers in light sockets. And children under the age of 4 need to be supervised and have all kinds of dangerous things kept out of reach.

While there is an undeniable possibility of electric shock, it is an exaggeration to say that such light sockets are not safe. There are countless millions of them installed and there is a negligible incidence of harm arising from them.
 

Offline TimFox

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #103 on: October 23, 2022, 04:55:11 pm »
What are the holes in the US prongs for? Are they for ball bearings to drop in and retain the plug? I presume they're not so some kid can bolt some wires to them...

If they are part of a retaining mechanism, shouldn't that mitigate against them falling out of the socket, but still allow them to pop out if the cable is snagged?

I don't know the original design requirement, but I have seen small padlocks inserted through the two flat-blade holes to prevent installation.
 

Offline TimFox

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Re: [YouTube]; American is impressed by sensible British mains plug design
« Reply #104 on: October 23, 2022, 05:01:43 pm »

This is precisely why strain reliefs fail, and is a practice which encourages unnecessary wear and tear and increases the chance of a fault in the plug or socket.

Yeh, maybe. But in my time, I've never actually seen a plug fail in this manner. They are extremely robust. That's not to say it doesn't occur, but it's rare.

A clean, low (physical) resistance break is far less likely to result in damage to a plug or socket. Even if it's unintentional (like you moving a vacuum cleaner just that bit too far), I'd rather just have it shut off because the plug was pulled as opposed to damaging pins or the wall socket itself.

Perhaps the extreme example in current use of a high physical resistance break is the US series of "twist lock" connectors, mostly used in industrial or commercial contexts for single or three-phase cordage. 
https://www.hubbell.com/wiringdevice-kellems/en/Products/Electrical-Electronic/Wiring-Devices/Locking-Devices/Insulgrip-Twist-Lock/c/2027741
Even if you drive away in your pickup truck with the compressor in the back still plugged in, you can't pull the mating connectors apart, but the cord on one end of the mated pair will fail, possibly exposing live wires.
 

Offline Gyro

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Re: [YouTube]; American is impressed by sensible British mains plug design
« Reply #105 on: October 23, 2022, 07:17:55 pm »

I'm fully aware the fuse has nothing to do with protecting the equipment.  However, the fuse also protects the plug and by extension the socket as well, and the BS1363 plug and socket is not rated to exceed 13 amps, therefore it is still required with 4mm^2 cable.  I can tell you having used a 10 amp electric car charger for some time on a BS1363 socket/plug that they don't like extended high current operation and begin to overheat,  a safe limit is around 8 amps. The idea of 32 amps being OK with the right cable is farcical.
The irony is that a lot of the heat in a heavily loaded 13A plug comes from the fuse, so on balance it may actually be safer overall to use an unfused 13A plug for a 10A car charger.

There are always Chinese suppliers happy to oblige. They'll even throw in a sleeved PE pin, no extra charge!  ::)


« Last Edit: October 23, 2022, 07:23:04 pm by Gyro »
Best Regards, Chris
 

Offline james_s

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #106 on: October 23, 2022, 07:22:41 pm »
What are the holes in the US prongs for? Are they for ball bearings to drop in and retain the plug? I presume they're not so some kid can bolt some wires to them...

If they are part of a retaining mechanism, shouldn't that mitigate against them falling out of the socket, but still allow them to pop out if the cable is snagged?

Nobody really seems to know. Technology Connections did a video about this but even he didn't have a concrete answer. Most but not all plugs have them and I've never seen a receptacle with a ball detent. Even twist-lock plugs have them.
 
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Offline james_s

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #107 on: October 23, 2022, 07:28:36 pm »
Quote
There have long been some niche products like that.
Not even niche,available from all good electrical wholesalers,nor that new, i first discovered them in the mid 90's , but if your  not playing with the stuff most days you may be excused for thinking that.They do have 1 minor down fall ,but that don't effect the end user,you need  another  adaptor in your testing kit as just probing the contacts dont work

They could be widely available and still niche. What matters is the installed base, not how easy they are to obtain. I could see them being useful in a child's room for example but in most cases I think it's probably easier to just teach people not to stick things in light sockets.
 

Offline IanB

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #108 on: October 23, 2022, 07:29:15 pm »
Nobody really seems to know. Technology Connections did a video about this but even he didn't have a concrete answer. Most but not all plugs have them and I've never seen a receptacle with a ball detent. Even twist-lock plugs have them.

This answer provided by Legrand seems to have a lot of credibility, since they actually make the plugs and should know why they do it:


 
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Online PlainName

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #109 on: October 23, 2022, 08:53:42 pm »
What are the holes in the US prongs for? Are they for ball bearings to drop in and retain the plug? I presume they're not so some kid can bolt some wires to them...

If they are part of a retaining mechanism, shouldn't that mitigate against them falling out of the socket, but still allow them to pop out if the cable is snagged?

I don't know the original design requirement, but I have seen small padlocks inserted through the two flat-blade holes to prevent installation.

Would be easier just to cut off the plug :)
 

Offline TimFox

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #110 on: October 23, 2022, 08:57:56 pm »
What are the holes in the US prongs for? Are they for ball bearings to drop in and retain the plug? I presume they're not so some kid can bolt some wires to them...

If they are part of a retaining mechanism, shouldn't that mitigate against them falling out of the socket, but still allow them to pop out if the cable is snagged?

I don't know the original design requirement, but I have seen small padlocks inserted through the two flat-blade holes to prevent installation.

Would be easier just to cut off the plug :)

Nonsense:  a padlock is reversible, and can be part of a lock-out/tag-out safety procedure.  https://www.osha.gov/sites/default/files/publications/factsheet-lockout-tagout.pdf
« Last Edit: October 23, 2022, 09:02:35 pm by TimFox »
 
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Offline mikeselectricstuff

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Re: [YouTube]; American is impressed by sensible British mains plug design
« Reply #111 on: October 23, 2022, 10:13:56 pm »

I'm fully aware the fuse has nothing to do with protecting the equipment.  However, the fuse also protects the plug and by extension the socket as well, and the BS1363 plug and socket is not rated to exceed 13 amps, therefore it is still required with 4mm^2 cable.  I can tell you having used a 10 amp electric car charger for some time on a BS1363 socket/plug that they don't like extended high current operation and begin to overheat,  a safe limit is around 8 amps. The idea of 32 amps being OK with the right cable is farcical.
The irony is that a lot of the heat in a heavily loaded 13A plug comes from the fuse, so on balance it may actually be safer overall to use an unfused 13A plug for a 10A car charger.

There are always Chinese suppliers happy to oblige. They'll even throw in a sleeved PE pin, no extra charge!  ::)



That's fine - the CCA wire will fuse at an amp or two anyway
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Online vk6zgo

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Re: [YouTube]; American is impressed by sensible British mains plug design
« Reply #112 on: October 24, 2022, 12:09:24 am »
There have long been some niche products like that. You made it sounds like bayonet lamps are safe. The vast majority are not.

To be practical about it, if you poke your finger inside a bayonet socket while it is switched on, the most likely outcome is that your finger will contact both pins at the same time. So the result will be that your finger gets zapped, which while painful, is not dangerous. Realistically, the probability of receiving a shock current that goes through your heart is low.

Falling off a ladder after being zapped is dangerous, though! ;D
Been there, done that ---not from a light socket, though!
Quote

We can also observe that every child over the age of 4 or so knows not to poke fingers in light sockets. And children under the age of 4 need to be supervised and have all kinds of dangerous things kept out of reach.

Spot on!

I can't believe so many people don't know where their little kids are, & yet scream "Somebody(else) is to blame for this!" if the child gets run over in the front driveway (often by the very same parents) or think that 4 year olds (or even 8 year olds) can safely  be left with a burning candle in the case of a power outage.

Maybe we were "helicopter parents" but our kids survived!
Quote

While there is an undeniable possibility of electric shock, it is an exaggeration to say that such light sockets are not safe. There are countless millions of them installed and there is a negligible incidence of harm arising from them.
 

Offline SL4P

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #113 on: October 25, 2022, 10:25:20 pm »
The standard UK plugs use a very coarse thread.
If the cable assembly is treated less than perfectly, those fat threads seem to vibrate loose… arcing often ensues.
Don't ask a question if you aren't willing to listen to the answer.
 

Offline Monkeh

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #114 on: October 25, 2022, 10:35:42 pm »
The standard UK plugs use a very coarse thread.
If the cable assembly is treated less than perfectly, those fat threads seem to vibrate loose… arcing often ensues.

I've never had an issue with them coming loose when fitted properly to begin with. The thread is also not specified, so you'll find it varies make to make, some are rather fine.
 

Online themadhippy

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #115 on: October 25, 2022, 11:19:37 pm »
For all you lovers of the uk plugs, a question.Do you prefer the  Mk loop it around the terminal or the more common poke the wire through the hole ? For me ,if im not paying its  mk, yea there a bit more   fiddly  to get a neat job with no stray strands poking out, but  thats outweighed by the wing type cord grip.The worst are those dam rubber plugs were you need to slide the top up  the cable before you fit the plug.
 

Offline Monkeh

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #116 on: October 25, 2022, 11:27:20 pm »
For all you lovers of the uk plugs, a question.Do you prefer the  Mk loop it around the terminal or the more common poke the wire through the hole ? For me ,if im not paying its  mk, yea there a bit more   fiddly  to get a neat job with no stray strands poking out, but  thats outweighed by the wing type cord grip.The worst are those dam rubber plugs were you need to slide the top up  the cable before you fit the plug.

Personally I prefer the hole, because I use ferrules. I also like the old fashioned two screw grip, it's rather reliable - as long as the plug isn't so cheap the base bends when you tighten it.
 

Offline Dundarave

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #117 on: October 26, 2022, 03:51:35 am »
You know, the fact that there are 5 pages (and counting) of comments on British plugs is, in itself, a commentary on the utility (or not) of something so ubiquitous and prosaic in our modern world.

It would be not even be worth talking about the (by comparison) tiny North American plugs if the British plug didn’t exist for contrast!  I guess the Brits can add that to the list of their plugs “superior attributes”, lol.
 

Online BrianHG

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #118 on: October 26, 2022, 04:13:08 am »
The real reason the US Nema plug power cords still have holes in them.  Here is what a production line for them looks like:



It allows for a cheap plastic injection molding holding the pins perfectly level during injection.
In the really old days, some plugs were a bent sheet of metal to thicken the plug pin with a hole on one side of that metal making a dent, but the hole would not go completely through.
 

Online PlainName

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #119 on: October 26, 2022, 10:13:37 am »
I'm more inclined to think that they use the hole because it's there rather than putting the hole in to help them. After all, if it were just for manufacture then some parts would have the hole, some not, and some have a differently sized one in a different position, and that could make socket contacts very variable in function depending on plug.
 

Offline Monkeh

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #120 on: October 26, 2022, 03:07:06 pm »
I'm more inclined to think that they use the hole because it's there rather than putting the hole in to help them. After all, if it were just for manufacture then some parts would have the hole, some not, and some have a differently sized one in a different position, and that could make socket contacts very variable in function depending on plug.

I seem to recall there's a point in the standard about the allowable size and location of said hole. It's not required, though, and some indeed don't have them.
 
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Offline MadScientist

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #121 on: December 22, 2022, 01:07:52 pm »
The 13A uk plug and socket is simply too big. That’s. It’s major failing it requires big back boxes , hard to make slimline extensions sockets and the insertion force is too great

It’s an example of the perils of a single design criteria , ie safety. When several criteria should have been used . I know older people who physically cannot unplug the plug.

These days with multiple RCBO protection , there’s no need for a single obscession on plug safety , equally is polarisation an issue, in reality

That’s. Not to say the plug is going to disappear but it’s has its drawbacks that’s clear
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Offline Monkeh

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #122 on: December 22, 2022, 03:34:31 pm »
it requires big back boxes

Non-issue

Quote
hard to make slimline extensions sockets

Eh? Non-issue.

Quote
equally is polarisation an issue, in reality

Yes.
 

Online tom66

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #123 on: December 22, 2022, 03:44:31 pm »
The 13A uk plug and socket is simply too big. That’s. It’s major failing it requires big back boxes , hard to make slimline extensions sockets and the insertion force is too great

It’s an example of the perils of a single design criteria , ie safety. When several criteria should have been used . I know older people who physically cannot unplug the plug.

These days with multiple RCBO protection , there’s no need for a single obscession on plug safety , equally is polarisation an issue, in reality

That’s. Not to say the plug is going to disappear but it’s has its drawbacks that’s clear

The shutters on sockets do prevent electrocution of curious children, for which the hazard current is much less than that for which an RCD would trip at.

The biggest failing (IMO) of the British plug is there's no accommodation for anything other than 13A plugs.  It would be nice to see something like a 32A plug built on a similar style (perhaps with backwards compatibility for 13A plugs?)  Such plugs could be used for higher power appliances (ovens, for instance) or portable EV charging.  I believe Australia allows this, it's common to find 20 and 25A sockets in kitchens.  Imagine a 32A kettle!  ;D

Polarisation is a real issue.  Most table lamps are single pole switched, and we do not have the concept of split phase like the Americans do with their 240V appliances.   The same applies to other appliances too.
 

Online themadhippy

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Re: [YouTube]: American is impressed by sensible British mains plug design
« Reply #124 on: December 22, 2022, 04:50:15 pm »
Quote
  It would be nice to see something like a 32A plug built on a similar style
there's ceeforms for that sort of thing,and all things domestic over a couple of KW  tend to be hard wired anyways.
 


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