dennis@home submitted this idea :
Screw terminals are very common on mains wiring, from a few amps to thousands of amps. Even crimped lug connections are held on terminals by nuts and bolts. They do not come loose if they are used properly. Aircraft do not use them because other methods are easier, quicker, more reproducible - the difference is the work isn't conducted out in the field, but under workshop conditions.
That's a common fallacy. It's the cost/benefit per unit that matters. The amount saved by economies only increases with the number of units. The benefit gained by not economising increases with the number of units.
Bill
Nuts and bolts aren't screw terminals and they use lugs not wires. They are significantly different.
If your house vibrates like an aircraft it needs seeing to.
Screw terminals are used as a cheap and cheerful way of connecting a one off. No reason to use them on a loom which will be fabricated, as in a car or aircraft. Also, given the complexity of an aircraft loom, size and weight could come in to it too.
But you're absolutely right. A properly tightened screw terminal (in a domestic setting) doesn't come loose. Those that do weren't properly tightened.
Temperature changes will loosen them over time. As will road traffic vibrations.
I have even seen corrosion on them due to condensation and wallpaper paste. Or that's what I thought it was. Once they start to corrode thats the end as far as screw terminals go, they aren't gas tight like a proper crimp joint should be.
Well, I rewired this house when I bought it in the '70s. And have added to that since.
Still waiting for a terminal to come loose.
I've seen it often on installations others have done, though. Likely an electrician deliberately making work for the future.
I use these:
Problem comes when you have to insert two wires into the same hole that's when it becomes a real pain. Such as when I needed to get the two earths into this. Why have only 5 connections when you should really have 6.
Think I'll give it a low review later.
While I've seen a few screws in plugs work loose etc, I've never seen it in a light fitting, junction box etc. - at least in a domestic setting.
Crimps are, of course, better- if done correctly. A 'nip' with pliers isn't correctly ;-)
They are gas tight if assembled correctly - the contact pressure of a through-hole terminal is many times than of a crimp, which is why the copper deformation is many times higher. The contact pressure of a wrap-around screw terminal is same order as a crimp.
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