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Old 2nd Nov 2018, 7:53 pm   #101
G6Tanuki
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Default Re: Modern MK Safety Plug. Not impressed

Quote:
Originally Posted by Brigham View Post
Quote:
Originally Posted by G6Tanuki View Post
Yes heating of the fuse is _very_ common in 13A plugs (one of the reasons I dislike the things...)...

...For high-current stuff I still like the old BS546 15A round-pin sockets, which are available in a nice dual-outlet metalclad version if you know where to look.
Me too.

I've found a source of switched single-outlet ones (Branded JoJo), but I've not seen duals.
Any chance of a subtle nudge in the right direction?
See here: https://www.mtxengineering.co.uk/pro...20Socket%20Box
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Old 2nd Nov 2018, 7:59 pm   #102
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Default Re: Modern MK Safety Plug. Not impressed

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I do recall being told that the reason for the lengths of the wires being different was to encourage the live to let go first, and the earth last...
?
There seems to be a popular idea that 'cutting the live short so it lets go first' is somehow safer, but that disregards the likelihood that the live will partially pull-out causing a (possibly perisstent) arc.

I prefer to wire all 3 cores equal, so if the cord-grip does fail the tension will be spread over the 3 conductors (minimising the likelihood of any pull-out), and the equipment will continue to operate (albeit slightly less-safely) until the failed cord-grip is picked up at the next inspection.
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Old 2nd Nov 2018, 8:54 pm   #103
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Default Re: Modern MK Safety Plug. Not impressed

Most plugs are designed so that the live is the shortest wire, so be it.
I always leave the earth with as much slack as possible.
There are some rubbish cord clamps around.
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Old 10th Nov 2018, 10:56 am   #104
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Default Re: Modern MK Safety Plug. Not impressed

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I don't think it was just the sleeved pins; I vaguely remember trade advertising which promoted the difficult-to-get-wrong cord-grip arrangement (in the past it was quite common to see plugs fitted with the card-strip-and-screws style cord-grip not tightened) and how it was easier to wire correctly because you could cut all three conductors to the same length rather than fiddling around with making each one a different length as was normal for other plugs.
I thought you were supposed to leave the earth wire longer so that if the cord got pulled out of the plug the earth was the last to go.
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Old 10th Nov 2018, 12:16 pm   #105
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Default Re: Modern MK Safety Plug. Not impressed

In that case, the plug design would simply need to be such that the route to the earth connection is shorter than to the line and neutral ones but with space to lose a bit of slack.

That way cutting all three wires to the same length would still meet the requirement.

In any case it's a known fact that whenever an "idiot proof" design is in progress, nature will be quietly evolving a better idiot

What about a plug design where the cable entry and grip is at the earth pin end?
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Old 10th Nov 2018, 12:52 pm   #106
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Default Re: Modern MK Safety Plug. Not impressed

During the 1990's I worked for a company that did IT supply & maintenance for government departments. It was a stated requirement of the contracts that mains plugs are to be wired with the L wire the shortest and the E wire the longest. When said equipment arrived at the customer's (new or post-maintenance), the plug wiring was often inspected by the customer's resident technicians. If the wiring was not as stated, the entire product was returned - even if the mains lead was of the removable variety.

Al.
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Old 10th Nov 2018, 2:17 pm   #107
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Default Re: Modern MK Safety Plug. Not impressed

Hello all.

Thought this plug might be of interest. I think I bought it around 1991, and our local hardware/electrical shop had them on display as the 'latest thing'.

I think, maybe, that the manufacturers hoped it would become the new Safety Plug.

Has anyone else seen one of these? Or heard of IDC Plugs Ltd? Google hasn't really told me anything!

PS. Forgot to say, the top cover is attached to the rest of the plug with quite a stiff hinge. It can make things a bit awkward having to hold it out of the way when wiring up the plug.
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Old 10th Nov 2018, 11:45 pm   #108
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Default Re: Modern MK Safety Plug. Not impressed

I remember these being promoted for some time, but by the early 1990s more & more electrical items had fitted plugs so they never really caught on.
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Old 11th Nov 2018, 2:32 am   #109
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Default Re: Modern MK Safety Plug. Not impressed

Strange- with a name like that you'd at least expect the plug itself to use IDC technology!

Though I guess the wide range of possible wire gauges would militate against that being particularly safe.
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Old 11th Nov 2018, 11:28 am   #110
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Default Re: Modern MK Safety Plug. Not impressed

How do you mean, Chris?

What sort of technology would be incorporated in a BS 1363 plug?

By the way, militate - nice word - and new to me! I had to look it up! ��
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Old 11th Nov 2018, 12:54 pm   #111
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Default Re: Modern MK Safety Plug. Not impressed

Insulation Displacement Connector.

Like Scotchloks or ribbon cable connectors.

Closing the lid would force the wires down into forks which displace the insulation and make direct contact with the wire inside. (Well technically I suppose a Scotchlok does it the other way round.)
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Old 11th Nov 2018, 1:10 pm   #112
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Smile Re: Modern MK Safety Plug. Not impressed

Oh, I see! Sorry, Chris, I hadn't heard of that before - although now you've described it, I see exactly what you mean.

Gosh, I am learning a lot today!
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Old 11th Nov 2018, 7:04 pm   #113
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Default Re: Modern MK Safety Plug. Not impressed

As an aside I once had (and maybe still have) an IDC American mains plug. It was designed to go onto what they call 'zip cord' -- single insulated twin cable a bit like speaker cable. You put the cable on top of the main body of the plug and slid the cover on which forced the cable onto a pair of offset IDC 'forks' attached to the pins. That was it. It could be fitted without any tools at all.

Of course it was dangerous in that nothing stopped you sliding the cover off again and touching the tips of said IDC forks. But perhaps not so lethal on 115V mains.
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Old 12th Nov 2018, 2:04 pm   #114
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Default Re: Modern MK Safety Plug. Not impressed

Just fitted an MK Toughplug. It may be okay for a 3A flex but for a 13A flex it was a real struggle to fit. The space was tight and the cord grip a total pain. Either you put the cord in first, then it was a struggle to get the wires to the pins, or you wired the pins first, then it was a struggle to get the cord into the grip. I think MK may well be losing their shine.
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Old 12th Nov 2018, 3:26 pm   #115
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Default Re: Modern MK Safety Plug. Not impressed

IDC for mains applications is well established: the waterproof light-bulb-sockets used for high-street coloured christmas-tree and similar street-lights are invariably IDC! I guess it makes sense when you've got to make up chains of a few thousand of the things.
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Old 12th Nov 2018, 4:36 pm   #116
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Default Re: Modern MK Safety Plug. Not impressed

The only reference to IDC I can find is to contractors.

Last edited by Scott37; 12th Nov 2018 at 4:38 pm. Reason: Inaccuracy after re-reading earlier post.
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Old 12th Nov 2018, 4:50 pm   #117
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Default Re: Modern MK Safety Plug. Not impressed

A search for "festoon lampholder" will find the IDC lampholders. The ones I have seen have been designed for use with special 2-core 2.5mm flexible mains cable.
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Old 13th Nov 2018, 10:09 am   #118
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Default Re: Modern MK Safety Plug. Not impressed

I think the main reason the earth wire was kept longer than the live wire was to prevent it working loose, unknown to the user, then working it's way down to touch the live connection with disastrous consequences.

I used to keep a black museum of photographs taken of customers plugs on equipment brought in for repair. I wish I could find it but fear it was skipped when I closed my shop. John.
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Old 13th Nov 2018, 10:30 am   #119
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Default Re: Modern MK Safety Plug. Not impressed

I wouldn't mind seeing that if it ever happens to turn up!
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Old 13th Nov 2018, 12:13 pm   #120
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Default Re: Modern MK Safety Plug. Not impressed

Here is some black museum photos to be going on with while you hunt for your book.
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