I'm sure glad UK plugs have fuses

[Fraser]

And to think moulded plugs were made law in the UK in order to improve safety 

I used to run a course teaching people how to wire a UK plug. The students liked the fact that they could actually put their on own plugs on rather than needing an electrician. A little knowledge can be dangerous however so I included examples of what can go wrong and the consequences.

Sadly with regards to the Chinese supplied moulded IEC leads, some are less than acceptable quality. I have been send so real weird versions of the UK plug. A really small body only just bigger than the pins footprint, no fuse, no insulation sleeves on L & N and suspiciously flexible cable. Very little copper in the conductors. Total rubbish fit only for the bin.

Aurora

[IanB]

Perhaps we could persuade Mike to pop some in his postal Xray unit and show the internals. I have taken a few apart and there is a lot of poor workmanship under the plastic overmoulding. Poor crimps. poor wire preparation ( nicked cores and loose strands outside the crimp) and often cable that is at best optimistically rated.

I just tried to disassemble one with a hacksaw. However, it appears they are not meant to come apart. The whole thing is layer upon layer of solid plastic. There is an outer layer of soft rubbery plastic, an inner shell of brittle plastic, and inside that the whole thing is filled with what looks like injected hard setting plastic. I can't even get to the wires and terminals.

[Zero999]

And to think moulded plugs were made law in the UK in order to improve safety 

What law is that?

Moulded plugs may be very common but there's no legal requirement for them.

[Towger]

Unfortunately MK of today is not the same quality brand of yesteryear. For example new model redesigned the MK (Duraplug) 4 way trailing socket is not a patch on the old version. The MBA playbook rules are used to run the company now.


Edit: Removed strange text at top of reply.

[wreeve]

My uni (Warwick) was the same Ian! And that was the late 90's! 5 amp round plugs!

[IanB]

What law is that?

Moulded plugs may be very common but there's no legal requirement for them.

The law requires appliances to be supplied with pre-fitted plugs. And no way is a person going to be sitting on an assembly line fitting plugs by hand. So plugs are fitted by machine on an automated production line. Which means moulded plugs.

[Howardlong]

EU Low Voltage Directive innit. Yes, 240VAC is low voltage as far as this directive is concerned.

Good idea, problem is now nobody knows how to wire a plug any more, they have to get an electrician in.

[G7PSK]

5 amp round pin plugs are used for lighting in places such as theatres a lot. I have seen a 13 amp socket used in airports where the pins are 90 deg rotated so that a standard plug will not fit, the idea is to stop the public plugin in their phones etc. and stealing electricity. The UK. 13 amp plug is used in Zimbabwe at least where plugs are used and bare wires are not just twisted together that is.

[SteveyG]

UK ring mains are 32A, while spurs are given a 16A breaker.

Not strictly true. What are you basing this information on?

[Red Squirrel]

Wow considering the beefy design of those plugs I imagine there was quite a lot of current going through to actually melt it, like 40a or more?  Those plugs seem somewhat similar to dryer plugs here in Canada which are rated for 30 amps at 240v.  Oven ones are rated at 40a.  Mind you the wiring in the oven and dryer plugs is probably way thicker.   #8 for ovens and #10 for dryers IIRC.

[bookaboo]

Good idea, problem is now nobody knows how to wire a plug any more, they have to get an electrician in.

Half the people didn't know how to do it before, which was the problem. Changing a plug is a pretty rare thing to do these days - usually the fuse goes and can be replaced, or outlasts the appliance anyway.

Look at it this way. The government used to have to make public information videos warning people not to use matches to push the earth cover open and then shove some bare wires into the live and neutral sockets. It's probably better than people don't even attempt to replace plugs unless they have been properly instructed to do so. I have but even so I can't recall a time when I actually needed to do it on an appliance.

I once had the Managing Director of a previous firm bring me a "faulty" piece of equipment that he had wired the plug on wrong. Live and earth mixed no less.

[SteveyG]

Wow considering the beefy design of those plugs I imagine there was quite a lot of current going through to actually melt it, like 40a or more?  Those plugs seem somewhat similar to dryer plugs here in Canada which are rated for 30 amps at 240v.  Oven ones are rated at 40a.  Mind you the wiring in the oven and dryer plugs is probably way thicker.   #8 for ovens and #10 for dryers IIRC.

The current was probably in the region of 20A with the fault being an inferior quality fuse holder which caused excessive heating from I²R losses.

[Howardlong]

Good idea, problem is now nobody knows how to wire a plug any more, they have to get an electrician in.

Half the people didn't know how to do it before, which was the problem. Changing a plug is a pretty rare thing to do these days - usually the fuse goes and can be replaced, or outlasts the appliance anyway.

Look at it this way. The government used to have to make public information videos warning people not to use matches to push the earth cover open and then shove some bare wires into the live and neutral sockets. It's probably better than people don't even attempt to replace plugs unless they have been properly instructed to do so. I have but even so I can't recall a time when I actually needed to do it on an appliance.

Blimey, no fun in your house, that's for sure!

[IanB]

The government used to have to make public information videos warning people not to use matches to push the earth cover open and then shove some bare wires into the live and neutral sockets. It's probably better than people don't even attempt to replace plugs unless they have been properly instructed to do so. I have but even so I can't recall a time when I actually needed to do it on an appliance.

Blimey, no fun in your house, that's for sure!

It was generally more fun to use a screwdriver to push the earth cover open and then push Meccano rods into the live and neutral sockets before shorting them with said screwdriver. Unfortunately the satisfying bang that resulted also resulted in significant parental displeasure at having to replace the main fuse, meaning that such excitement was only available once without risk of severe sanction 

[Chris Jones]

What law is that?

Moulded plugs may be very common but there's no legal requirement for them.

The law requires appliances to be supplied with pre-fitted plugs. And no way is a person going to be sitting on an assembly line fitting plugs by hand. So plugs are fitted by machine on an automated production line. Which means moulded plugs.

Someone in China hand-wired the plug on my Asda extension lead - or at least they got most of the way through it, but didn't bother to do up the earth screw so the wire subsequently lost contact with the pin.

I will generously assume that it was tested and that the wire fell out after it passed the earth resistance test.

[G7PSK]

Wow considering the beefy design of those plugs I imagine there was quite a lot of current going through to actually melt it, like 40a or more?  Those plugs seem somewhat similar to dryer plugs here in Canada which are rated for 30 amps at 240v.  Oven ones are rated at 40a.  Mind you the wiring in the oven and dryer plugs is probably way thicker.   #8 for ovens and #10 for dryers IIRC.

The usual problem with the plugs is at the point where the fuse clip is riveted to the live pin, on all the plugs that I have had that melted or just got hot for that matter, the problem was loose riveting causing a high resistance point.

[vk6zgo]

It is a safe assumption, as fuses have been not allowed as either replacement or new here since the 1960's, and the old fuse boxes are only still allowed to be used until there is any upgrade made, which then requires the new wiring or socket outlet ( original socket outlets would be a 5A socket, the plugs for which are still common, but which are typically now only used for suspended lighting in a ceiling void or for hanging lights under 500W, and the standard now is a 15A outlet) to pass the modern standard, which calls for a circuit breaker and a residual current device. The PVC wiring was made mandatory in the 1960's, so any install with a fuse box would likely have cotton covered wire.

In any case the standard now calls for the earth to be provided by a dedicated wire, not like in the old scheme where the steel conduit was used for earth. thus in any case you will be doing a rewire with 3 cores of cable, though likely you will be replacing the old 4mm cables with 2.5mm cables, so you can fit them still in the steel conduit. Most DCC wire here at the coast will fail insulation test in any case, just from it absorbing water from the humid air. 77% RH and 28.5C at the present here in sunny Durban in the evening.

So, yes, you are making assumptions based on where you stay, not about where this thread is about.
My parents house (that's here in the UK, not SA) was last rewired by the government in the 70s, and it has a fuse box along with PVC wiring, so in the UK, it's perfectly OK to have that combination, along with no requirement to rewire or replace anything.

In Australia,there was a mandatory shift to PVC wiring & a bit later,plugs in the mid to late 1950s,so that anything wired after that time will have basically similar wiring.
The DCC stuff was pretty well non-existent by then,anyway.

Fuse holders were made so that anything other than 10A (lights) or 16A (power) fusewire could not be used.
They are still legal,but modern installations use circuit breakers.