Regarding spring-loaded 'quick-connectors' on accessories in at least some other countries...


- Someone here mentioned  terminals on the output of a Hager AFDD in another thread, a few weeks ago.  


- The US has its "back-stab receptacles" - see the picture "Stab-In Connection to Neutral Bus" for how the wire is held in a very simple configuration of spring-edge against flat. This is quite a similar principle to some European sockets I've seen with very simple, low-cost quick connectors.

The wago connector shown below is quite different, as the wire first passes through an eye - making it hard to avoid getting all strands through - and it is then clamped there with a nice little bend that helps it not slip. (These pictures are not meant to show a good way to prepare the conductor; they're the first I found in my assortment.)
  


- A lot of schuko sockets, light-switches, and even CEE (3-phase) 16 A sockets and plugs, that I've seen in Sweden, have gone over to quick-connector terminals. However, my experience is that these are usually not at all as nice as the piano Wagos.

It may feel ok getting a wire in, but getting it out of some models can be hard and can bend the spring teeth making them clearly not as tight next time. There's generally a knack, such as to hold in a fiddly little release button or insert a screwdriver, and to push the conductor a little inwards and then draw it out with a gentle wiggle. There's also the matter of what happens to the strands of the commonly used 7-strand 1.5 or 2.5 mm2 conductors (used in conduit) when pushed in: some models make it easy for these to splay out internally, not making good contact but not obvious from the outside. Twisting helps for this, but it's not obvious that twisting is the overall best choice, though I tend to do it anyway as I worry more about having few strands in contact than about having a smaller contact area to the terminal. I've not come across a strongly 'evidence-based' recommendation either way. Manufacturers don't usually mention twisting. 

I've taken many of these switches or schuko sockets to pieces to see how the conductors are held and released, and whether I really want to use them in long term installations. Still, I prefer to pay extra for the screw versions - which usually are a bit more like a small cage than a screw-tunnel. A view I heard from an  installation inspector was to 'ask the fire service' about which is the better choice. They meant there are more problems with the quick-connectors, but I really doubt that the installed populations of different types are well known, and it's not fair to compare the good and bad quality designs all together within the categories of "screw versus quick", and there's the matter of whether users have followed the instructions about bared length etc. 

Anyway, although some of the accessories with quick-connectors seem nice, many feel only really quick for assembly, and not very solid. If the manufacturers would have terminals like the piano Wago I'd be much happier. Perhaps the rather chunky nature of multiple solid-core 2.5 mm2 conductors into BS1363 sockets, with little clearance room in the back-box, is one reason for not trying quick connectors yet. When it happens, I hope it's not done following the cheapest practice. I can imagine a good design would be very convenient and could be better than trying to get three or four conductors held properly in a tunnel or cage. 


I was just going to mention that I don't remember seeing spring-loaded connectors above about 30 A, when I saw mapj1's comment and picture. Impressive. 

Regarding spring-loaded 'quick-connectors' on accessories in at least some other countries...


- Someone here mentioned  terminals on the output of a Hager AFDD in another thread, a few weeks ago.  


- The US has its "back-stab receptacles" - see the picture "Stab-In Connection to Neutral Bus" for how the wire is held in a very simple configuration of spring-edge against flat. This is quite a similar principle to some European sockets I've seen with very simple, low-cost quick connectors.

The wago connector shown below is quite different, as the wire first passes through an eye - making it hard to avoid getting all strands through - and it is then clamped there with a nice little bend that helps it not slip. (These pictures are not meant to show a good way to prepare the conductor; they're the first I found in my assortment.)
  


- A lot of schuko sockets, light-switches, and even CEE (3-phase) 16 A sockets and plugs, that I've seen in Sweden, have gone over to quick-connector terminals. However, my experience is that these are usually not at all as nice as the piano Wagos.

It may feel ok getting a wire in, but getting it out of some models can be hard and can bend the spring teeth making them clearly not as tight next time. There's generally a knack, such as to hold in a fiddly little release button or insert a screwdriver, and to push the conductor a little inwards and then draw it out with a gentle wiggle. There's also the matter of what happens to the strands of the commonly used 7-strand 1.5 or 2.5 mm2 conductors (used in conduit) when pushed in: some models make it easy for these to splay out internally, not making good contact but not obvious from the outside. Twisting helps for this, but it's not obvious that twisting is the overall best choice, though I tend to do it anyway as I worry more about having few strands in contact than about having a smaller contact area to the terminal. I've not come across a strongly 'evidence-based' recommendation either way. Manufacturers don't usually mention twisting. 

I've taken many of these switches or schuko sockets to pieces to see how the conductors are held and released, and whether I really want to use them in long term installations. Still, I prefer to pay extra for the screw versions - which usually are a bit more like a small cage than a screw-tunnel. A view I heard from an  installation inspector was to 'ask the fire service' about which is the better choice. They meant there are more problems with the quick-connectors, but I really doubt that the installed populations of different types are well known, and it's not fair to compare the good and bad quality designs all together within the categories of "screw versus quick", and there's the matter of whether users have followed the instructions about bared length etc. 

Anyway, although some of the accessories with quick-connectors seem nice, many feel only really quick for assembly, and not very solid. If the manufacturers would have terminals like the piano Wago I'd be much happier. Perhaps the rather chunky nature of multiple solid-core 2.5 mm2 conductors into BS1363 sockets, with little clearance room in the back-box, is one reason for not trying quick connectors yet. When it happens, I hope it's not done following the cheapest practice. I can imagine a good design would be very convenient and could be better than trying to get three or four conductors held properly in a tunnel or cage. 


I was just going to mention that I don't remember seeing spring-loaded connectors above about 30 A, when I saw mapj1's comment and picture. Impressive.