13 amp plugs - memories

[Dave Fawthrop]

| I feel partly responsible for this thread being the second 'poster' | Problem, how can I view the latest postings wthout having to trawl | through all the posting dates! There's got to be a better way! =20

Mailgate is a web based server which are the absolutely worst way to read newsgroups. Get Agent or any other newsreader, Even Outlook Express is better than a web based server. Subscribe to a *real* newsserver, like NIN, News.individual.net .

With a newsreader and a newserver you download new posts onto your own machine, and you can set the newsreader so that you see only the posts which have arrived since you last looked at that newsgroup.

--=20 Dave Fawthrop

17,000 free e-books at Project Gutenberg! Yorkshire Dialect go to

[Bob Eager]

If you read carefully, you'll see that *I* didn't say that. I'm sure Andrew will explain.

Yes, but (in my example) I never turned off the switch first. I pulled the plug, and current didn't stop flowing - it arced.

[Chris Bacon]

.... or just install Thunderbird (free from

[Andy Dingley]

Yes - but the question is what happens when you _don't_ switch it off first.

AC drops to zero 100 times a second. Break the circuit (in any way) and within 10mS the current will cease and the circuit is broken.

DC supply does not drop to zero - you have to arrange "switchgear" to do this yourself, per appliance or socket. With a switch there's a mechanical springines in there so that the contacts fly apart quickly, soon breaking the circuit by a safe distance.

If however you unplug a DC appliance, the circuit is broken slowly and there will be some arcing. If there's a large current flowing at the time, this arcing can be severe. The usual hazard is gradual build-up of burnt insulation, and burnt insulation is usually carbon - now a poor conductor. This can heat up and cause a fire later. If you use an under-rated (or AC) switch on DC then the arc may be so severe that it forms a conductive arc across the open switch (arcs have low resistances). You may not even be able to switch the circuit off!

AC is safer for all sorts of reasons. Unless you're an elephant, of course.

[Andrew Gabriel]

If you ionise air into a plasma (arc), it's actually quite a good conductor. In the case of a DC supply, as Andy already said, there's no regular interruption to the current to allow the arc to quench.

The switches in DC sockets used fast-break toggle action with two separating contacts (effectively doubles the separation speed) with large contact gap to try and quench the arc the arc before it ever gets a chance to establish. You are unlikely to pull a plug out fast enough to achieve the same effect.

BTW, if you never saw a switch arc across, try this MPEG...

arc was entinguished by tripping an upstream breaker when it reach ~100' long. There's a full description of the fault at is AC and only about 100A; DC would have been very much worse.

[David Hansen]

On Tue, 10 Jan 2006 17:55:17 +0000 someone who may be Owain wrote this:-

It must be a fairly old book. The 15th and 16th editions certainly refer to plugs and socket-outlets. IIRC the 15th edition came out in around 1980.

[Dave Plowman (News)]

Collins GEM English Dictionary plug n. thing fitting into and filling a hole; device connecting an appliance to an electricity supply;

[Mark Carver]

Yes very well, the house was (still is) fed by overhead line, so the mains earth was connected to an earth rod outside.

The mains was the only earthy thing I could easily use. We had electric storage heating, I'd sometimes use that with a croc clip on the grill.

[Rob Morley]

Blasted Bolshevik :-)

[Mike Clarke]

Reminds me of the BC lamp bulbs with 3 locating pins instead of the usual 2. No doubt to discourage employees from nicking the bulbs' The extra cost of the specials must have been far more than the cost of a few bulbs walking off site.

[Andy Dingley]

Weren't those (railway anyway) an odd voltage anyway?

[Bob Eager]

I think so...but I heard that the problem was that the people who stole them didn't know that....so they stole them (once) anyway...

[Andrew Gabriel]

They used to be used to distinguish mercury vapour lamps which needed external ballast from self-ballasted ones, in streetlamps, to avoid unfortunate accidents.

[Owain]

The editions are dated 1917 and 1933.

I quote:

Wall Plugs. A "wall plug," or "socket" as it is sometimes erroneously called, consists of two parts - the socket or fixed part, the terminals of which are permanently connected to the circuit wires, and the moveable part, called the plug top which, by means of a flexible cord, is connected to a table lamp, etc., ... (Private House Electric Lighting, F H Taylor, 1917)

Owain

[Andy Wade]

Nice :-)

[Doctor Drivel]

Plug top? I haven't heard that term in 20 years. When they were called 'wall plugs', then plug top made sense. Now it is 'socket', it sounds very odd.

[<me9]

Weren't th coloured bulbs in flame effect fires 3 pronged. I seem to remember you couldn't fit an ordinary BC lamp, so boosting the manufacturer's profits.

[Chip]

On 11 Jan 2006 20:21:41 GMT,it is alleged that [e-mail] (Andrew Gabriel) spake thusly in uk.d-i-y:

Also in Fireglow lamps for (Berry Magicoal ISTR) electric fires. In order to make you pay large amounts for the replacements.

A standard brass BC lampholder fitted the bracket however, indeed sometimes just the brass shell could be swapped.

[Dave Plowman (News)]

It's crap, though. A plug is a male member and fits into a socket. 'Decency' has stopped perhaps more erudite terms being used. ;-)

If someone invented a plug which could mate with another plug (electrical wise) they'd make a fortune.

Problems in nomenclature arise with many multi-pin designs where the bodies have opposite sexes to the actual connectors - audio XLRs are a prime example. But the connectors are the business end, so that's how you decide which is which. Unless there is a mixture. ;-)

[Frank Erskine]

Was that 3 prongs, or 3 contacts? ISTR something like that, but if you had 2 contacts diametrically opposed and 3 prongs there'd be a problem getting it to make contact except by trial and error...

Still OT, I used to have an Atlas fluorescent lamp in the workshop "at home", the starter of which was in the form of a 60W lamp with a 4-pin base, two of which were the starter itself, and I think the lamp formed a sort of ballast - there was no choke.