Anyone solder wires into mains plugs?

[BigRedX]

My parent's house that they lived in from 1968 to 1980 had every single type of socket distributed throughout the rooms. Often it would provide challenging if you wanted to move an electrical appliance to a different room as it may not have the correct type of socket in the room and if it did it might be on the opposite wall to where you wanted to plug your device in. My bedroom had 15, 13 and 5amp sockets on different walls as well as a hard-wired connection to an electric radiator, and later another hardwire connection to the storage heater (on a different wall). I was well used to changing plugs on my electrical appliances before I was 10.

[tauzero]

11 minutes ago, sprocketflup said:

When I think of what electrical current is on an atomic level, i.e. electrons jumping/being passed from one atom to another, it makes me think of the idea that all the cells in our bodies are renewed from time to time, therefore we literally arent the same people we were 7 years ago ( I think it was 7 years). So, whenever I'm looking at an old piece of cable, it occurs that it may not be the same as it was when it was put in years ago.

With electrons moving, maybe that would explain why I encounter as an electrician, loose screws in electrical fittings so often. And it's a fact that we are not allowed to use junction boxes that utilise screws in places that are/will become inaccessable, under a wooden floor that is being tiled over for example, instead we must use accessories that have sprung fittings for the cables.

 

AIUI the electrons only travel a short way, then knock an electron out of the atom they're joining, which then moves on in its turn. So there isn't a huge migration of electrons into and out of the wire.

 

The cells in our body are a bit different, as it's actually cells replicating and old cells dying that causes the renewal.

 

Given how small electrons are, it's more likely that it's repeated thermal expansion and contraction, plus vibration, that eventually causes a screw to loosen. And of course there's always the chance that whoever did it up didn't do it up tightly enough.

[sprocketflup]

Indeed yes, usually only as far as the next atom. Hence me saying "on an atomic level". So the wire or whatever will still have the same amount of overall atoms in, even after many years of (undisturbed) service. 

The heat cycles are indeed the most likely culprit for loosening screws as you say. 

[Stub Mandrel]

Funnily enough I just posted an explanation of why crimping is superior to soldering.

 

The same goes for plugs. Done up tight the screw cold welds and unsoldered is more flexible, improving fatigue life.

Edited November 18 by Stub Mandrel

[Stub Mandrel]

On 15/11/2025 at 13:23, itu said:

You can solder Al, but it is complicated because of oxidization et al. Still crimping is considered superior to other solutions. 

 

You can soft solder to aluminium. You need to abrade off the oxide layer, cover it with light oil (not flux), use a powerful iron and scratch through the thin oxide layer that formed before you got the oil on.

 

It is tricky.

 

I've also got aluminium welding rods (alutite), used with a blowtorch- mechanical abrasion also important. 

[Stub Mandrel]

On 15/11/2025 at 12:59, SpondonBassed said:

 

When user serviceable domestic mains plugs were the norm screw clamped terminals made it possible for average home owners to rewire plugs.  Back in the day, there were several types of mains plug and it was necessary to be able to change them to suit the type of socket at the user's home.  People are no longer expected to do this so plugs are now crimped and sealed.  

 

Crimping is widely used in electronics.

 

It's particularly useful in avionics when aluminium wire is used to save weight.  You can't solder aluminium.

 

Hooray for crimping!

 

 

 

Sone posh plugs have washers you loop the wire round.

 

Plugs with little scews are better (if they are quality ones) because if they can be done up tight enough they cold weld like a crimp... you hear them creak or crack when undoing them.

[NancyJohnson]

On the OP, for as long as I can remember I've tinned the bare copper when I wire a plug.  Always felt a well tinned cable end will be stronger than splayed copper strands.

 

Doesn't really make any difference to electrical performance, does it?  

 

Also, I'll tin the ends of speaker cables for the hifi as well.

[Mottlefeeder]

7 hours ago, NancyJohnson said:

On the OP, for as long as I can remember I've tinned the bare copper when I wire a plug.  Always felt a well tinned cable end will be stronger than splayed copper strands.

 

Doesn't really make any difference to electrical performance, does it?  

 

Also, I'll tin the ends of speaker cables for the hifi as well.

I think it depends on the amount of solder you use. 

My understanding is that silder will ooze under pressure, so your screw-tight pressure will reduce over time, and eventually become a faulty connection.

David

[BigRedX]

On 23/11/2025 at 10:21, NancyJohnson said:

On the OP, for as long as I can remember I've tinned the bare copper when I wire a plug.  Always felt a well tinned cable end will be stronger than splayed copper strands.

 

Doesn't really make any difference to electrical performance, does it?  

 

Also, I'll tin the ends of speaker cables for the hifi as well.

 

This came up on another forum, and the advice from several experienced electrical engineers was that a better and more permanent contact between the screw terminal and the wire conductor was achieved if you did not tin the wires, because the copper strands can compress and essentially cold weld to the terminal under the pressure from the screw.

[Stub Mandrel]

1 hour ago, BigRedX said:

 

This came up on another forum, and the advice from several experienced electrical engineers was that a better and more permanent contact between the screw terminal and the wire conductor was achieved if you did not tin the wires, because the copper strands can compress and essentially cold weld to the terminal under the pressure from the screw.

 

This.

[Phil Starr]

On 16/11/2025 at 14:02, Steve Browning said:

My Dad had one of these in his gig bag.

 

I think I still have one of these alongside a bayonet plug to connect a plugboard to a light fitting

 The good old days 😲

[Phil Starr]

On the serious side, don't solder your mains cable, if you do want to tidy up the wire ends (and escaping strandd of mains cables are a hazard) then you can use a crimp connector over the stripped ends. You often find these on the few wired plugs around. 

 

I prefer wired rather than moulded plugs as I often chnage out the mains cable, either because of wanting a different length but also so I can change to a nice flexible cable rather than the overly stiff plastic that a lot of gear comes with. However I don't think I've ever had a moulded mains cable actually break and wonder why I look down on moulded mic/guitar cables which frequently need re-soldering?

[KingBollock]

If worried about the screws backing out, loosening the connection, then perhaps a threadlocker might be a solution? You can get different strengths, one that makes a connection that can be broken, and a stronger one for a more permanent connection.

 

We have two different types of plug sockets in our living room. There’s the normal one, and then there’re are ones that have round pin holes. Those are for lights and are controlled by switches next to the main light switch.

[BigRedX]

If a screw terminal UK mains plug has been properly constructed and competently wired, then there shouldn't be a problem even if the screws do work loose.

 

1. The conductor wires can't come apart from the terminals on the plug contacts because there is nowhere for them to go with the cable clamp in place. 

 

2. Even if the screws come completely out of the holes there is nowhere for them to go as they are captured by the construction of the plug casing. I haven't tried this but I suspect that there probably isn't enough room in the plug casing for them to become completely unscrewed anyway.

 

3. The cables inside the plug can't be moved by external forces because the cable clamp at the entry point prevents this.

[neepheid]

Believe it or not, a lot of thought went into the design of the UK plugs and sockets...