For those needing more power sockets, and a couple of 1A USB ports....

NOT

Yes, I remember those from the mid '70s. Its good that they've gone.

I don't remember those - just a few 3-pin plugs & sockets, which all seemed to be reserved for relatively high-powered devices.

And power distribution strips fitted along to top of the tiling behind a kitchen worksurface. They were similar in construction to the track spots that tended to decorate UK ceilings in the '70s, but much longer. You could snap in two-pin sockets and slide them along to where you wanted them. Were they a good idea? I always wondered.

Actually, I still think that some of the safest mains sockets are the Australian/New Zealand type:

The pins are extremely narrow (6.3 x 1.6mm, 1/4" by 1/16" if you prefer), and so don't need a mechanical shutter. The contacts in the socket only contact the remote half of the pins, so touching anything live by pushing metallic things into the holes is really quite difficult. The are rated for 240v at up to 10 amps. As these are based on an early US design I wonder why it was discarded in favour of the apparently less safe current types.

Its stood the test of time well too: they've stayed pretty much the same since the '30s while the UK has used at least four mutually incompatible domestic types in the last 40 years alone - and I'm only talking about plugs for small appliances and lighting, i.e 13 amps or less.

--
martin@   | Martin Gregorie 
gregorie. | Essex, UK 
org       |

That can't happen in practice. There are just two situations, which in the UK we refer to as an overload current, and a fault current.

An overload current happens when a circuit or cable is passing more current than it is designed for, although it's not faulty. An example would be plugging in too many high current appliances on one circuit.

A fault current is where there is a short circuit, and the current flow is limited only by the impedance of the supply and cable conductors. The current flowing is very much higher than the overload current case above, at least until the fuse/breaker blows.

There aren't any likely fault scenarios where the fault would pass something like 15A for long - the high power dissipated at the fault site (small) will either quickly blow the fault open circuit, or short circuit, and either way, the situation quickly resolves.

Yes. Having the fuse linked with the thing it's protecting makes fault diagnosis easier, and reduces impact on other appliances.

--
Andrew Gabriel 
[email address is not usable -- followup in the newsgroup]

... and far too many appliances and devices that have polarized plugs for no valid reason. It gets awfully frustrating to try to plug in something only to have the plug refuse to go in. If the plug is balky going in the way, it becomes necessary to closely inspect both the plug and the outlet to see which side is wider.

Or, the nightlight you want to put in the lower socket and have it face downward, only to find it insists on facing upward only.

Bah, Humbug!

--
Robert Riches 
spamtrap42@jacob21819.net 
(Yes, that is one of my email addresses.)

Fortunately, a minute with a file removes unnecessary polarization. ;-)

--
-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon

How do you know that? I think that depends on the nature of the short. That is the point. A short doesn't have to be extremely low impedance, it can be some moderate value that simply draws too much current for the paltry line cord.

Here in the US we have an odd connector for a 20 Amp 110 volt circuit where one pin on the plug is turned sideways. The socket has that pin shaped like a T so that either the 15 Amp plug or the 20 Amp plug will go into it. If you don't know about such things it is easy to plug a 15 Amp device into the 20 Amp socket and now the line cord might have to carry 20 Amps for an indefinite period.

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Rick

On 7 Feb 2015 04:05:28 GMT, Robert Riches declaimed the following:

Goes back to having a single sided switch that only cuts the lead to the base of the bulb socket... Upside down and the rest of the socket is live regardless of the switch position.

If they used double-pole single-throw switches, it would be no problem.

--
	Wulfraed                 Dennis Lee Bieber         AF6VN 
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

In comp.sys.raspberry-pi message , Fri, 6 Feb 2015 06:15:30, Ahem A Rivet's Shot posted:

UK sockets are commonly directly attached to ring mains, which IIRC are designed to be able to give 30A permanently; so the protection in the "fuse-box" must necessarily allow the supply of somewhat above 30A for quite a while. 30A @ 230V => HOT.

The more intelligent European Mainlanders, knowing that their plugs lack fuses, will ensure that their sockets will not supply much more than their rated current; that reduces the danger. The rest of them can be classed as potentially self-eliminating problems.

--

   Web   - FAQish topics, acronyms, & links.

Almost all night lights are completely enclosed in plastic, so there's

*never* any problem.

When is it time to start talking about the Pi? ;-)

--
-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon

Night lights are all LED now. No socket to worry about.

--

Rick

For night lights, LEDs are increasingly popular, and they make the most sense, IMO. However, the incandescents are still being sold. I saw some on a store shelf just a few weeks ago. Google hits say they're available from many vendors. Here's one example:

Here's the product description:

Amerelle, 4 Pack, Auto Night Light, 7W, Replaceable Incandescent Bulb Per Light, 120V, Automatic On At Dusk Off At Dawn, White Base, Contemporary Clear Prism Lens, UL Listed, For Replacement Bulb Use TV #706-095, Blister Pack Card.

--
Robert Riches 
spamtrap42@jacob21819.net 
(Yes, that is one of my email addresses.)

it takes approx 3 mA accros the hear to kill so whether a skt can supply

30A or only 10A does not make a significant difference to its ability to kill Also note it takes a fuse considerable time to blow (Hours) at its rated current capacity or just over, for blow "instantly" usually requires at least 10X the rated capacity.

The purpose of a fuse is to prevent fire due to continuous overload not to protect human life.

the introduction of RCCD circuit breakers help in this respect but even circuits equipped with these devices can deliver a fatal shock in the right (wrong?) conditions.

--
To write good code is a worthy challenge, and a source of civilized  
delight. 
-- stolen and paraphrased from William Safire

On Sat, 07 Feb 2015 22:12:17 -0500, rickman declaimed the following:

Tell that to my father -- his place is full of those critters that use large Christmas Tree light bulbs.

The two night lights I have aren't LED either... Some sort of electroluminescent panel, and no switch at all.

--
	Wulfraed                 Dennis Lee Bieber         AF6VN 
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

The answer is a few lines above in the text you quoted.

There are no such scenarios, for the reason given above.

I don't know the rules on appliance flexs in the US, but across all the EU, the thinner appliances flexs have short maximum lengths, so that their resistance is still low enough to blow the 16A installation breaker quickly enough on a short circuit to prevent the flex overheating. We don't need this protection in the UK because we have fused plugs, but it's imposed across the whole EU because of the free trade area in appliances, so you can't produce an appliance for just the UK with a longer flex, which would not be safe on the continent.

--
Andrew Gabriel 
[email address is not usable -- followup in the newsgroup]

If you don't wish to discuss this, why reply?

--

Rick

In comp.sys.raspberry-pi message , Sun,

8 Feb 2015 13:20:13, alister posted:

Fire is a common cause of termination of human life.

--
 (c) John Stockton, nr London, UK.  For Mail, see Home Page.  Turnpike, WinXP. 
 Web   - FAQ-type topics, acronyms, and links. 
 Command-prompt MiniTrue is useful for viewing/searching/altering files. Free, 
 DOS/Win/UNIX now 2.0.6;  see my .

Not to protect human life from electrocution, Happy now?

--
> Tut mir Leid, Jost, aber Du bist ein unertraeglicher Troll. 
Was soll das? Du *beleidigst* die Trolle! 
	-- de.comp.os.unix.linux.misc

The patented shutter design on many MK branded sockets does not involve the earth pin at all, a Euro plug goes in as if it was designed to!

--

Graham. 

%Profound_observation%