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Old 16th Aug 2010, 8:23 pm   #41
ppppenguin
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Default Re: Award for the worst plug design goes to...

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Originally Posted by Lucien Nunes View Post
Still looking for a Kliegl to take pics of...
Lucien
Almost at the bottom of the page. Are these Kliegels?
http://itsallaboutthelight.weebly.co...y-control.html
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Old 16th Aug 2010, 8:57 pm   #42
Alan Stepney
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Default Re: Award for the worst plug design goes to...

Although not the worst design, this one is unusual.

By rotating the top, it converts from 2 pin to bayonet. This example dates from 1953 or 54.
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Old 16th Aug 2010, 9:44 pm   #43
Lucien Nunes
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Nope, those are stage pins, the standard connector in US theatres for loads over 20A. They have flaws, e.g. you can get a finger into the socket tubes and you can mate them in various incorrect positions, also the leverage of the large body can distort the pins but by comparison they are modern and refined.

I am talking about a connector that consists of a slab of asbestos board with two pieces of brass attached on opposite edges, that wedges into a rectangular slot with corresponding contacts inside. Nothing is enclosed, you can jam your fist into the socket or hold the two plug terminals when live. There were better types with bakelite bodies, not so much fun though. They came in different widths for different currents. You could put two half-inch plugs side by side in a one inch socket.

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Old 16th Aug 2010, 11:01 pm   #44
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Default Re: Award for the worst plug design goes to...

Kats post reminds me .When I was 17 the government made me do a Youth training scheme thing .As i wasnt forthcoming in suggestions ,but had helped a freind with theatre lighting , they made me do one at a youth travelling theatre in Devizes .Anyway the portable dimmer unit was wired up by one of the leaders in such a way it had two leads and plugs ... so if you pulled one out it would have live pins Sorry slightlyO T .. I did like using the 15 amp plugs though on the lamps
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Old 17th Aug 2010, 9:47 am   #45
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Default Re: Award for the worst plug design goes to...

One thing I'm always very dubious about are these power rail things for connecting up lights etc. A long rod with a slit in the front, and inside the slit the power rails. Always seems to me to be like an extremely long socket with no shutter. I guess they must be OK or they wouldn't sell them would they?

BTW, on the subject of forgetting to put the cover on the mains plugs, I once knew a technician who wired up a whole 50-pin connector and then realised he had forgotten the cover ...
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Old 17th Aug 2010, 1:14 pm   #46
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Default Re: Award for the worst plug design goes to...

MMMm,

haven't we all?

50 way D-type with original Cannon type backshell come to mind- plus many variations on the military circular types.

My memory is of a Socapex 50A 4 pin 600V rated connector used for mains input with the live socket on the cable and a fixed bulkhead plug- turned out to be possible to scoop so that you could connect line to earth via the backshell on the free part- BANG!

http://194.2.77.62/ged/amphenol/download.asp?id=2193

See 34H.

Just because it's 600V rated, doesn't mean it's OK for mains!
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Old 17th Aug 2010, 1:50 pm   #47
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Default Re: Award for the worst plug design goes to...

How about the 15 pin Painton connector used by the BBC for their white front modules. On mains powered modules pin 1 was live. If you are working with a slightly misaligned chassis or on the bench with a free socket it's all to easy to stick a locator pin on the plug into pin 1 of the socket. Since you are usually holding a metal part in each hand at the time this is unpleasant. How do you think I know this What was potentially even worse was a few pounds of module falling locator pin downwards towards my foot. Fortunately it missed.

Link Electronics used the same connector for some of their products. They cut the offending locator pin off completely.

There's not much wrong with the rugged Cannon EP4 connector, once widely used for mains in the film and broadcast world. Except for 2 different wiring conventions which meant that neutral and earth could easily be shorted together.
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Old 17th Aug 2010, 1:54 pm   #48
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Default Re: Award for the worst plug design goes to...

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turned out to be possible to scoop so that you could connect line to earth via the backshell on the free part- BANG!
I don't understand this and I suspect I'm not the only one. What do you mean by "scoop"?
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Old 17th Aug 2010, 5:25 pm   #49
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Default Re: Award for the worst plug design goes to...

Scoop- misalign a connector pair so that transient unwanted connections are made during an attempt to mate them.

It seems an apposite term since the motion of the connector half in your hand is akin to that of scooping something up with a trowel or similar and you do scoop up something (albeit an unwanted connection).

No idea if it's in general usage, but at any rate people I work with seem to know what I mean
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Old 18th Aug 2010, 3:59 pm   #50
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Default Re: Award for the worst plug design goes to...

I'll also have to admit it. I use 2-pin Clix and the very dodgy Empire screw 2-pin ones. If I can find the Empire then I'll post a picture.

Last edited by Darren-UK; 19th Aug 2010 at 9:31 am. Reason: FSK problem fixed.
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Old 18th Aug 2010, 9:32 pm   #51
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Default Re: Award for the worst plug design goes to...

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Scoop- misalign a connector pair so that transient unwanted connections are made during an attempt to mate them.

It seems an apposite term since the motion of the connector half in your hand is akin to that of scooping something up with a trowel or similar and you do scoop up something (albeit an unwanted connection).

No idea if it's in general usage, but at any rate people I work with seem to know what I mean
That's a new term to me!
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Old 19th Aug 2010, 12:24 pm   #52
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Default Re: Award for the worst plug design goes to...

You've got me going, now....

Found this: http://www.dmctools.com/catalog/glossary.htm

Scroll down to "S".

I guess it may be a term originating from across the pond

A quick Google also suggested that the Mars Rover fell foul of a scooped connector at some point!
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Old 19th Aug 2010, 1:00 pm   #53
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Default Re: Award for the worst plug design goes to...

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That's a new term to me!
And me also. Herald1360's link gives it credibility though...
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Old 21st Aug 2010, 12:11 am   #54
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Default Re: Award for the worst plug design goes to...

Hi all!
I sometimes thiink the design of the standard 13 Amp plug to BS1363 spec. is a good candidate for poor plug design. Consider the following:
1. Little screws to secure wires of varying thickness.
2. Each wire must be the correct colour and in the correct place
3. Each wire has to be the of a different length as per drawing on the piece of card that may be fitted over the pins when you buy the plug or the top won't fit.
Example.
Green & Yellow wire 34mm free length with 6mm bared
Blue wire 22 mm free length - 6mm bared
Red wire 12 mm free lengyh - 5mm bared
4. Correct rating BS 1362 spec. fuse should be fitted
5. Anyone can fit a plug to any cable

For some time CE rated equipment has been sold with a plug attached to the power lead during manufacture to ensure correct fitting. But the user has to OPEN the plug to change the fuse and any rating of BS 1362 fuse will fit. How many plugs are out there with a wrongly rated fuse?

Discuss . . .

Cheers

Cheers MM
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Old 21st Aug 2010, 11:51 am   #55
Leon Crampin
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Default Re: Award for the worst plug design goes to...

I would agree with some of your comments and it's worth looking at mains plugs in a wider context.

The ring main is an obvious way to wire a building such that all of the copper in the walls is used all of the time. This concept requires a fuse at each outlet. The fuse could have been in the wall socket, but the designers for some reason chose to put it in the plug.

There are several unfortunate consequences arising from this decision. The plug is far too large for 90% of its intended applications. To prevent the plug from becoming even larger, a cut down radio fuse was chosen. Because a large variety of cable sizes have to be accommodated, strain relief is difficult to arrange effectively.

The other more serious problem is that even with silver plated end caps and silver plated phosphor bronze fuse clips, it won't carry 13A without an excessive temperature rise - and definitely not when used for a while in an adverse environment causing tarnishing. Radio fuses were never designed for these currents.

The unplated brass pins fitted to the majority of plugs become tarnished and in conjunction with hard brass socket clips (as opposed to phosphor bronze) further add to the temperature rise problem - old rubber plugs in cheap sockets wired to 3 kW heaters are dangerous in my view and can cause fires.

So, my award for the worst design of plug goes to the authors of BS1363 for making poor fundamental decisions and for writing a specification which lacks detail to the point of being a joke. For there to be no specified maximum hot spot limit at full current and after full ageing and use in a corrosive atmosphere (or even 5 years in a garden shed) is negligent.

Leon.
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Old 21st Aug 2010, 1:17 pm   #56
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Default Re: Award for the worst plug design goes to...

Yes, I've always thought it ironic that wiring a plug is the one electrical job most people will tackle but it's one of the tasks I hate the most. At least they seem to have stopped making those plugs where you have to wind the bared end round a stud, they were a real pain in the proverbial. Also, does a plug really need to be so bulky? With portable equipment where the cable has to be stowed their is invariably barely enough room for the plug.
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Old 21st Aug 2010, 1:34 pm   #57
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Default Re: Award for the worst plug design goes to...

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At least they seem to have stopped making those plugs where you have to wind the bared end round a stud, they were a real pain in the proverbial.
The MK646 is still made AFAIK. Probably the best quality 13A plug on the market. The stud and nut fixing is more secure than the usual terminal and less likely to break strands. Also with an excellent cord grip and equal length wires to each terminal.

As for the ring final, I sense that it's becoming less popular. It can suffer from open circuit faults that leave it working but potentially unsafe. 20A radials using 2.5mm cable and 32A radials using 4mm cable seem to becoming more common. With a 20A radial you don't really need a fuse in the plug but we're stuck with that.

13A plugs are not the world's worst design. Look at Italy, Australia and the US for some fairly horrible plugs though at least all of these are compact. At the other end of the spectrum I'd nominate the German Schuko style as the best domestic mains connector.
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Old 21st Aug 2010, 2:07 pm   #58
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Default Re: Award for the worst plug design goes to...

The idea of securing a wire under the TIP of a screw has never seemed right to me. The high pressure at the tip and the fact it rotates can easily result in the wire being reduced to a few strands.

This can be even worse when trying to secure solid single conductor wire in a mains socket. The screw can miss the wire altogether. Securing three wires in a socket (ring main plus spur) is very hit and miss. You tighten the scew and find that at least one wire can easily be pulled out.

I prefer terminal strips where a piece of metal is interposed between the screw and the wire so that a pure clamping force is applied or crimped on spade terminals under a screw HEAD.
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Old 21st Aug 2010, 5:55 pm   #59
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Default Re: Award for the worst plug design goes to...

With the wires wound round a stud the danger is that most of the strands will escape when you tighten the nut. This is more likely if you wind it anticlockwise as the nut will be trying to unwind it. This makes it less foolproof than the wire through a hole design. I agree it would be better to include a clamping strip between the screw and the wire on the wire through a hole type plugs.
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Old 22nd Aug 2010, 9:47 am   #60
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Default Re: Award for the worst plug design goes to...

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With a 20A radial you don't really need a fuse in the plug but we're stuck with that.

But then you've got the problem of a 20A fuse protecting an appliance with a 3A or 5A cable that would otherwise be unfused. Lamps come to mind, the only fuse in a lamp is the one in the plug.

If anyone remembers the Philips TV's the with the MD range of chassis, the mains switch used to break down and burn out, Due to poor design on Philips part, the main fuse inside the set was on the set side of the mains switch. The burnt out switch relied on the plug fuse to protect it.

Slightly OT Does anyone know how mains wiring is carried out in Europe or where they have European wiring?
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