The MK Safety plug
Discussion
WinstonWolf said:
Smiler. said:
WinstonWolf said:
When you wire a plug correctly all three wires are different lengths after the cord grip. If there's enough force on the outer sheath to pull it from the pins and leave the plug in the socket the live will fail first.
If the strain relief provided by the cord grip is compliant with the requirements of the BS or EN (IEC) standard with which it complies, then the plug will be ripped from the socket before the strain relief gives way - assuming that it has been fitted in the correct manner by a suitably qualified person.Strain relief is there to protect against such mechanical damage.
Many years ago there was a uk plug made by dorman smith. The live pin was a screw in fuse. The pin/fuse would come loose an leave the live pin in the socket when the plug was pulled out, deadly if touched. https://www.google.co.uk/search?q=dorman+smith+plu...
speedyman said:
Many years ago there was a uk plug made by dorman smith. The live pin was a screw in fuse. The pin/fuse would come loose an leave the live pin in the socket when the plug was pulled out, deadly if touched. https://www.google.co.uk/search?q=dorman+smith+plu...
That's interesting.Also from that page The Museum of Plugs
The internet always delivers
Tom Scott does a really good video on why UK plugs are so good.
https://youtu.be/UEfP1OKKz_Q
I'm saying this while looking down at my wife's american hairdryer with the exposed live terminals. In the bathroom. Next to the sink.
If a UK sparky saw US electrical safety standards they would have a fit...
https://youtu.be/UEfP1OKKz_Q
I'm saying this while looking down at my wife's american hairdryer with the exposed live terminals. In the bathroom. Next to the sink.
If a UK sparky saw US electrical safety standards they would have a fit...
Great thread, seriously. 
I'm a big fan of those MK plugs too, but I can't remember the last time I wired a plug
https://www.bing.com/images/search?q=badly+wired+p...
I'm a big fan of those MK plugs too, but I can't remember the last time I wired a plug
https://www.bing.com/images/search?q=badly+wired+p...
Brother D said:
I'm saying this while looking down at my wife's american hairdryer with the exposed live terminals. In the bathroom. Next to the sink.
Bro Ive been there had dark thoughts but its not worth it. Relationships work themselves out eventually, rigging an accident just ain't the way to deal with ittechiedave said:
Brother D said:
I'm saying this while looking down at my wife's american hairdryer with the exposed live terminals. In the bathroom. Next to the sink.
Bro Ive been there had dark thoughts but its not worth it. Relationships work themselves out eventually, rigging an accident just ain't the way to deal with it
Gotta say I don't rate those MK plugs at all...couple of issues:
1] As you screw down on the cable, despite the washer that is supposed to hold the cable in place, they invariably grab on and pull the cable round the screw.
2] If you screw down too hard (sometimes not that hard), the screw simply snaps off because it's clamped down at an angle.
I'm not that struck on the cable clamps either.
1] As you screw down on the cable, despite the washer that is supposed to hold the cable in place, they invariably grab on and pull the cable round the screw.
2] If you screw down too hard (sometimes not that hard), the screw simply snaps off because it's clamped down at an angle.
I'm not that struck on the cable clamps either.
Worth bearing in mind that the uk 13A plug is fused, the plug is fused because our wiring standard uses the ring main rated at 32A.
The european schuko plug and us plugs are not fused because the building wiring is different. Using plugs without fuses in uk buildings represents a very serious hazard to life and property plus a darwin award entry.
The european schuko plug and us plugs are not fused because the building wiring is different. Using plugs without fuses in uk buildings represents a very serious hazard to life and property plus a darwin award entry.
gottans said:
Worth bearing in mind that the uk 13A plug is fused, the plug is fused because our wiring standard uses the ring main rated at 32A.
The european schuko plug and us plugs are not fused because the building wiring is different. Using plugs without fuses in uk buildings represents a very serious hazard to life and property plus a darwin award entry.
bThe european schuko plug and us plugs are not fused because the building wiring is different. Using plugs without fuses in uk buildings represents a very serious hazard to life and property plus a darwin award entry.
ks.techiedave said:
thebraketester said:
They are referring to the internal wiring not the external pin length.
Here's a question for you. When wiring up a plug, do you guys remove the pins when connecting the wires and then replace them? Or do you leave the pins in the socket?
Riveting stuff.....
Very good question. I can see you are being a little humorous by the question and then the comment Rivetting stuff. Here's a question for you. When wiring up a plug, do you guys remove the pins when connecting the wires and then replace them? Or do you leave the pins in the socket?
Riveting stuff.....
Well as you know the pins are not removeable in the MK safety plug they are secured down (riveted in) you might say so it's not possible to remove them when wiring up the MK Safety Plug. This is not the case with other plugs as many do indeed allow the pins to be removed.
Personally I leave the pins in on other brands I do tend to unscrew the cord grip completely on one side and near complete on the other and then sort of lift it up and turn it at right angles to its normal position. Then once the important pin terminal connections have been made I rotate it back and screw it down. I also make sure that the earth terminal is screwed down even when it's not required.
I always offer the cable up, cut the wires to the correct length, then remove the pins and connect the wires then replace the pins. Makes it easier IMO
I used to wire plugs badly without realising that what I was doing was dangerous in the long term.
My dad taught me to always tin the ends of the stranded wire with solder before putting them into the screw terminals of the plug. It keeps things neat and prevents stray strands, and intuitively seems like an obvious enhancement to safety.
But it's wrong.
The problem is that solder is a soft metal, and will 'creep' over the course of a number of years, especially when subjected to the pressure from a screw terminal. When you tin the ends of the wire, the solder goes in between the strands and occupies the space, so when you screw it into the terminal the solder is taking a lot of the pressure. Over the years, the apparently solid solder behaves in a somewhat liquid way and will 'flow' away from the pressure, thus leaving a much looser connection than it was originally. Eventually all the current is going through a very small amount of metal. You may also get some arcing. Both of these will lead to overheating, and possibly even fire.
By contrast, leaving the copper strands bare means there's nothing in between them when you tighten up the screw terminal. The strands are pressed tightly together, so it's the copper taking all the strain. Copper is much less ductile than solder, and the 'creeping' effect will probably take hundreds or thousands of years rather than, say, 10 years with solder.
So ignore my dad. Don't tin the ends of stranded wire that you're going to put into a screw terminal!
My dad taught me to always tin the ends of the stranded wire with solder before putting them into the screw terminals of the plug. It keeps things neat and prevents stray strands, and intuitively seems like an obvious enhancement to safety.
But it's wrong.
The problem is that solder is a soft metal, and will 'creep' over the course of a number of years, especially when subjected to the pressure from a screw terminal. When you tin the ends of the wire, the solder goes in between the strands and occupies the space, so when you screw it into the terminal the solder is taking a lot of the pressure. Over the years, the apparently solid solder behaves in a somewhat liquid way and will 'flow' away from the pressure, thus leaving a much looser connection than it was originally. Eventually all the current is going through a very small amount of metal. You may also get some arcing. Both of these will lead to overheating, and possibly even fire.
By contrast, leaving the copper strands bare means there's nothing in between them when you tighten up the screw terminal. The strands are pressed tightly together, so it's the copper taking all the strain. Copper is much less ductile than solder, and the 'creeping' effect will probably take hundreds or thousands of years rather than, say, 10 years with solder.
So ignore my dad. Don't tin the ends of stranded wire that you're going to put into a screw terminal!
Dr Mike Oxgreen said:
I used to wire plugs badly without realising that what I was doing was dangerous in the long term.
My dad taught me to always tin the ends of the stranded wire with solder before putting them into the screw terminals of the plug. It keeps things neat and prevents stray strands, and intuitively seems like an obvious enhancement to safety.
But it's wrong.
The problem is that solder is a soft metal, and will 'creep' over the course of a number of years, especially when subjected to the pressure from a screw terminal. When you tin the ends of the wire, the solder goes in between the strands and occupies the space, so when you screw it into the terminal the solder is taking a lot of the pressure. Over the years, the apparently solid solder behaves in a somewhat liquid way and will 'flow' away from the pressure, thus leaving a much looser connection than it was originally. Eventually all the current is going through a very small amount of metal. You may also get some arcing. Both of these will lead to overheating, and possibly even fire.
By contrast, leaving the copper strands bare means there's nothing in between them when you tighten up the screw terminal. The strands are pressed tightly together, so it's the copper taking all the strain. Copper is much less ductile than solder, and the 'creeping' effect will probably take hundreds or thousands of years rather than, say, 10 years with solder.
So ignore my dad. Don't tin the ends of stranded wire that you're going to put into a screw terminal!
To much of a faff anyway !My dad taught me to always tin the ends of the stranded wire with solder before putting them into the screw terminals of the plug. It keeps things neat and prevents stray strands, and intuitively seems like an obvious enhancement to safety.
But it's wrong.
The problem is that solder is a soft metal, and will 'creep' over the course of a number of years, especially when subjected to the pressure from a screw terminal. When you tin the ends of the wire, the solder goes in between the strands and occupies the space, so when you screw it into the terminal the solder is taking a lot of the pressure. Over the years, the apparently solid solder behaves in a somewhat liquid way and will 'flow' away from the pressure, thus leaving a much looser connection than it was originally. Eventually all the current is going through a very small amount of metal. You may also get some arcing. Both of these will lead to overheating, and possibly even fire.
By contrast, leaving the copper strands bare means there's nothing in between them when you tighten up the screw terminal. The strands are pressed tightly together, so it's the copper taking all the strain. Copper is much less ductile than solder, and the 'creeping' effect will probably take hundreds or thousands of years rather than, say, 10 years with solder.
So ignore my dad. Don't tin the ends of stranded wire that you're going to put into a screw terminal!
I wonder what percentage of the public can actually wire a plug ?
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