Even the mighty DuraPlug …

[Michael GilliganParticipant @michaelgilligan61133]

… dies of fatigue eventually:

 

Unplugging my extension lead t’other day was interesting to say the least.

The top came off in my hand, and the live bits remained in the socket:

.

 

The rubbery plastic post, with its little brass threaded insert was the ‘single point of failure’

… be warned.

MichaelG.

[DC31kParticipant @dc31k]

Possibly repairable with a bookbinder’s screw.

[Mark RandParticipant @markrand96270]

One thing I’ve noticed with Duraplugs is that as sulfur fumes outgas from the Vulcanised rubber, tin sulfide is formed on the fuse end caps. Unfortunately, this doesn’t conduct electricity. A number of times over the years, both at work and at home, I’ve had to remove the fuses and either clean or replace them.

[Mark Rand]

On Mark Rand Said:

One thing I’ve noticed with Duraplugs is that as sulfur fumes outgas from the Vulcanised rubber, tin sulfide is formed on the fuse end caps. Unfortunately, this doesn’t conduct electricity. A number of times over the years, both at work and at home, I’ve had to remove the fuses and either clean or replace them.

Just buy a new plug, not worth electrocuting yourself for a couple of quid

[Michael GilliganParticipant @michaelgilligan61133]

Plug was removed and condemned, immediately after photographing it for the forum.

I’m definitely with Duncan on this one !!

MichaelG.

[Martin ConnellyParticipant @martinconnelly55370]

The lesson from this should be to only use Duraplugs in switched sockets. It is an example why it is always a good idea to switch off a socket before removing the plug.

Martin C

[SamsarandaParticipant @samsaranda]

I’ve noticed that after a while the rubber used for Duraplugs age hardens and becomes brittle, I was under the impression that vulcanised rubber wouldn’t do this, I must admit I have had a similar occurrence with a Duraplug in the past.   Dave W

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I also agree with Duncan. Faulty/broken plugs should always be replaced with a known good one. I’ve never liked those Duraplugs myself.

Regards Nick.

[Anthony KnightsParticipant @anthonyknights16741]

A lot of the so called 13amp plugs and sockets these days are simply not up to the job. My son recently had the plug on a tumble drier burn out. I myself have noticed the plug on a 2kw fan heater getting hot after a short while. Not sure if it’s the plug, socket, or the combination of the two which is at fault. Are these items tested, before allowed to go on sale?

[Bob Unitt 1Participant @bobunitt1]

I had a one side of a double-socket fail showing signs of excess heat. I was using both sockets for heaters, assuming that each would handle a full 3 Kw  (12.5 amps each, total 25 amps – which is less than 13 amps * 2). I was later informed by an electrician friend that, even though each individual socket is rated 13 amps, the double-socket as a whole is only rated at 20 amps. If you want multiple 3 Kw appliances connected, they need to be on physically separate sockets.

[noel shelleyParticipant @noelshelley55608]

The 13A SQUARE PIN plug WASN’T a good idea in the late 50s when I first saw them., and things have only got worse. The idea of the ring main and individual fuse plugs was based on cost and ease NOT safety ! It is at best difficult to get anything but point contact on the pins, then there is the issue of GOOD contact to the fuse and finally there is the electric fire, better known as the fuse ! Washing machines, tumble driers, fan heaters, in fact anything that draws much current will cook this type of plug with the risk of fire. The european 16A system has small round pins and our old 15A round pin plugs would happily take 30A, each socket wired individually and fused at the board Why does almost ANY method of pin connection use ROUND PINS ?  In the 50s there wasn’t even a standard voltage – Bornemouth was 200V Noel.

[densleighParticipant @densleigh]

Does anyone  remember the older  ‘Wylex plug’ ?   round pin (hollow) in centre and two offset smaller ‘square’ pins at each side. and not much in the way of cable restraint.

Socket was on a porcelain base with a bakerlite cover alll surface mounted on a wooden ‘plinth’ and of course wired in TRS or waxed cotten in older (1910’s) earth was usually an ‘optional’ extra in unsheathed tinned 7/029’s

 

NZ and other countries use dedicated sockets and back to distribution board fuses / mcb’s

No in plug fuses.

 

John

[noel shelleyParticipant @noelshelley55608]

YES I remember them ! In the context of the 13A plug the poorer the quality the greater the fire risk, and the quality of some is all but criminal ! Noel.

[duncan webster 1Participant @duncanwebster1]

1. Whether on a ring main or radials surely you’re better off with a fused plug, provided the fuse is matched to the flex as they often aren’t.

[Bob Unitt 1]

On Bob Unitt 1 Said:

I had a one side of a double-socket fail showing signs of excess heat. I was using both sockets for heaters, assuming that each would handle a full 3 Kw  (12.5 amps each, total 25 amps – which is less than 13 amps * 2). I was later informed by an electrician friend that, even though each individual socket is rated 13 amps, the double-socket as a whole is only rated at 20 amps. If you want multiple 3 Kw appliances connected, they need to be on physically separate sockets.

Fuses get hot in normal operation and most of the heat is dumped into the Live pin and hence into the socket.  A fuse is a short length of thin Copper wire of higher resistance than the cable.   As they work by melting a metal wire at about 1000°C, shouldn’t be a surprise that fuses get warm!   If a 13A plug is carries anywhere near 13A for a long time, any plastic near the live pin will eventually develop signs of being cooked.   The problem is thermal rather than electrical, and the cooking very slow.  Never heard of a fully loaded 13A fuse starting a fire, but I’ve seen many discoloured plugs and sockets.

Deeply upsetting to economically minded model engineers who believe technology should last for centuries, but the answer is to replace damaged plugs and/or sockets.

Dave

 

[duncan webster 1]

On duncan webster 1 Said:

1. Whether on a ring main or radials surely you’re better off with a fused plug, provided the fuse is matched to the flex as they often aren’t.

I have often felt that plugs sold separately should be fitted with a 3 rather than a 13 amp fuse, giving the option of fitting a larger one if needed.

[Andy StopfordParticipant @andystopford50521]

The thing that used to irritate me about Duraplugs was cramming (with some difficulty) the cores into the rather limited space, connecting them up, and then finding I’d forgotten to thread the top onto the cable…*

I reckon you should restore it, Michael, complete with period correct red, green and black core insulation.

*Some 2-pin continental plugs have this fun feature too.

[SillyOldDuffer]

On SillyOldDuffer Said:

 

………………  Never heard of a fully loaded 13A fuse starting a fire, but I’ve seen many discoloured plugs and sockets.

……………………………….

Dave

 

There’s quite a few videos and articles about fake/counterfeit fuses on the net, including this fairly spectacular short excerpt.
As far as I know, genuine 13a fuses are filled with sand or similar to absorb/dampen the arc flash.

The second longer video explores it in a bit more depth; I saw it ages ago, but not re-watched it all today

And finally playing with high currents on a plug & socket

https://www.youtube.com/watch?v=NPDG4aQ0PE8

Bill

p.s. this reminded me of one of my posts on the old forum

[Mark RandParticipant @markrand96270]

The only time I’ve ever seen an overheated 13A plug has been when the line or neutral screw was loose, leading to a high resistance connection as the copper gradually oxidised.

Personally, I think that the ring main, with fused plugs is the best and safest system in use in the world. The fuse can be correctly sized for the load and you only need a dozen to 15 breakers in the average house instead of the more than 50 that I would need in my 2 1/2 bed semi even with a single breaker protecting twin sockets.

[Roger BParticipant @rogerb61624]

Long ago I was involved with endurance testing 13A plugs and sockets. Only the best quality thermosetting plastic plugs were capable of long term 13A. Normally the live pin assembly failed due to the additional heat from the fuse. This often left the pin and fuse in the socket bare and live.

The continental ‘Fuse Per Room’ system generally doesn’t require many more breakers than the UK ring and lights per floor system.

The biggest problem with the UK BS1361 plug and socket is mechanical. There have been many injuries due to people being hit on the head or in the eye by the plugs on items being lifted off the top of cupboards etc. or by people stepping on the upturned pins of a plug (several stages worse than a Lego brick). Most continental unfused plugs, especially the universal (except in Britain) Europlug lie flat on the floor.

[Mark RandParticipant @markrand96270]

Maybe now we’ve been subjected to the idiocy of brexit, we can go back to the red, yellow and blue phases being those colours instead of brown, grey and black. 😀

[Nicholas FarrParticipant @nicholasfarr14254]

Hi densleigh, I’ve never seen those Wylex plugs that you mention, but I do have an old Crabtree 5 amp socket without an integral switch, this has a porcelain base with a brown bakerlite cover, which would have been mounted on a round wooden plinth fixed to the wall, with its own cable back to its own fuse.

I can remember my father having one of these in his shed, which had only a twin outlet, and when I was about five or six, I was in there with him once, and I put two of my fingers over both the holes, and they must have been small enough back then, to just make contact with the terminals, and soon found out they bite, learnt not to that again.

Regards Nick.

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