Joining thin wires

[RichardS]

After reading this, I, for one, accept that tinning and soldering are not a good idea - and I've done both in the past.

Why are choc blocks worse than crimped connections, or those push-fit choc-block-like things?

Supported choc blocks are fine unless you are using them in the bilges and there is some water around.

The connectors behind the switch panel in most (all?) boats is basically a big choc block.

Richard

 

[Ru88ell]

Blimey. Thanks all.

 

[grumpy_o_g]

Current British / European Standards etc.

Soldering joints has been deprecated for more years than I care to remember and is now very much a last resort as far as wiring and cabling is concerned (pretty much confined nowadays to PCB assembly and legacy products)

I suppose you'll be telling me next it''s a good idea to tin stranded cable before making a connection!



Fair enough but that wasn't clear

I'm not getting into an argument over this, it IS what I do for a living and has been for over forty years man and boy. What college lecturers teach in colleges has always been years, often decades, behind the real world and a lot of people in the industry don't know any better for that matter

Soldering two wires together, with or without heatshrink etc, has never i fact been good practice at any time although it's one we've all resorted to. However, it is now actively considered bad practice and to be avoided. Given the availability of far better alternatives, do it at your peril is all I'm saying!

Never read such rubbish from an apparently otherwise intelligent man in my life. Soldering is actively considered bad practice? You've just grounded just about every airliner and military vehicle, ship and aircraft in service!!!

If you want to use crimps or other connectors go ahead as there's little difference if the joins are done properly but to say soldering is actively discouraged is ridiculous.

To the OP, the comments about solder joint producing a stress point where the solder ends are absolutely true and is one reason for using heatshrink - all joints should be supported where possible though (sometimes by looming to other cables in a harness perhaps for example. For some reason people seem happy to overlook the fact that exactly the same problem exists with a crimp or any other connecter though. At some point the rigid connection stops and the wire is free to flex. You could argue that crimps and other connectors are worse as the connector is heavier - I have no idea if that's true as I just don't do permanent unsupported connections.

Bru - like you I've been doing this for well over 40 years and I have no idea what industry you're working in but your comments are just wrong. Solder is still used extensively and successfully and is actually required in many critical applications. Ask Airbus for example, or the RAF, or NASA or the guys in Blandford Camp (Army Sigs) or even the EMC engineer doing some work for me the other day.

 

[prv]

The connectors behind the switch panel in most (all?) boats is basically a big choc block.

Mine is spade terminals on the backs of the switches, with the corresponding fittings crimped onto the wires. The fusebox, the negative busbar, and the barrier strip that connects the external runs to the wiring inside the enclosure, are all screw terminals with crimped forks on the wires.

Just to keep the other side of the argument happy, most cable joints outside the main panel enclosure are soldered and then covered with adhesive-lined heatshrink

Pete

 

[Bru]

Dammit, it did it again! Take two. ..

Grumpy, you're misunderstanding what I wrote or perhaps I didn't make it clear

Solder is, of course, still widely used in many appropriate applications

What is deprecated is the jointing of wires by soldering them together and there is, and has been for many years, a general trend away from the use of solder terminations in cabling

The aviation industry is one area in not familiar with so I cannot comment but for example soldering cable terminations went out of favour in the lift industry four decades ago as crimps were found to be significantly more reliable

Soldering still has its applications such as panel wiring and component assembly, and of course PCB work, but when it comes to joining cables or making cable connections to equipment in all the industries I've worked in crimp connections superceded solder joints a long time ago

Like I said, I don't make this stuff up

PS. For an idea of what industry I'm working in, my sig might just be a clue!

 

[Hydrozoan]

... Why are choc blocks worse than crimped connections, or those push-fit choc-block-like things?

Here’s my take on it, but an electrician will be able to give a better answer I’m sure.

Simple chocstrip has screws, but there are better types with a flat metal plate on the screw which provides a more secure grip. In a dry location, my simple chocstrip had worked fine for probably 15-20 years, but as part of a general wiring update I replaced it with a Wago 12-way connector (see #7) which is tin plated (the chocstrip was not – though there was very little sign of verdigris) and specifically designed to cope with very fine cables. The grip jaws are flat (like the better chocstrip) and the ‘push’ grip is very, very simple to use with very fine cables in a confined space - probably my main reason for choosing it. The cost difference was trivial (ca. £5 vs. 50p?) in relation to my time and effort.

A simple crimped connection can obviously be readily sealed with heatshrink. For multiway connections with larger cables, I use a multiple screwpost connector with crimped and heatshrinked ring terminals. For very fine stranded instrument cables, one could use very small (green, I think) crimped and heatshrinked pin terminals (though they are not very readily available) and clamp those in the chocstrip/Wago - less likelihood of corrosion creeping up the wire. I did not think the effort was justified in my case as the location is dry and it is even quicker than with chocstrip to demount the cables and check for corrosion.

 

[grumpy_o_g]

Dammit, it did it again! Take two. ..

Grumpy, you're misunderstanding what I wrote or perhaps I didn't make it clear

Solder is, of course, still widely used in many appropriate applications

What is deprecated is the jointing of wires by soldering them together and there is, and has been for many years, a general trend away from the use of solder terminations in cabling

The aviation industry is one area in not familiar with so I cannot comment but for example soldering cable terminations went out of favour in the lift industry four decades ago as crimps were found to be significantly more reliable

Soldering still has its applications such as panel wiring and component assembly, and of course PCB work, but when it comes to joining cables or making cable connections to equipment in all the industries I've worked in crimp connections superceded solder joints a long time ago

Like I said, I don't make this stuff up

PS. For an idea of what industry I'm working in, my sig might just be a clue!

Ah, OK. My apologies in that case, though I still think there's a case for using solder in one or two situations. I probably over-reacted as you're one of the few I rely on to publish common sense in this place so my apologies again.

Aviation industry would normally tell you to replace the cable or loom sadly. Temporary fixes are often solder as that's the only way to keep it thin enough to go back into the loom if they are thin wire.

Didn't spot your sig at first so I didn't do very well. Engage brain and then type

 

[Lon nan Gruagach]

Cheap choc block is bad because the screw cuts the cores. Tinned and crimped or screw terminal is bad because over time the solder flows and the compression is lost.
Crimps are just as good as solder but both must be done meticulously right, thus the specification of the proper crimp tool. Crimping is much faster and is easier for machines so it has become more popular.

And, if you want fine, try a coax with o/d less than 1mm, soldered centre and crimped screen + insulation. fiddliest connector I have done is a TV85: several video, some screened audio pairs, some power and a whole load of control cores all in a 3" dia plug.

edit add: worlds worst connector ever are 5 pin din.

 

[Bru]

Ah, OK. My apologies in that case, though I still think there's a case for using solder in one or two situations.

Indeed and I won't deny that there are times when it's the only viable solution even when the standards say otherwise (a key difference, in my personal universe, between a technician and an engineer is that a technician will always do it by the book because he knows no better, an engineer will know when to break the rules, when he can break the rules. and, crucially, how to break 'em!)

I probably over-reacted as you're one of the few I rely on to publish common sense in this place so my apologies again.

No apology necessary at all - I wasn't as clear as I could have been so it deserved challenging. I am blushing slightly by the way!

Aviation industry would normally tell you to replace the cable or loom sadly. Temporary fixes are often solder as that's the only way to keep it thin enough to go back into the loom if they are thin wire.

Interesting - a parallel example on yachts and mobos being radar cables which are the very devil to joint effectively. Likewise complete replacement would be the ideal way to go but that isn't always a practical, or for that matter cost effective, option. Given enough space I'd always go for a shielded junction box if possible but sometimes there simply isn't anywhere to hide it and needs must

There's also a degree of pragmatism involved. If you're re-making one connection out of several dozen that are already soldered, there's not much point in going to significant lengths to avoid soldering the remade connection. If, on the other hand, you're re-doing the lot from scratch or if it's practicable to use crimps* rather than solder that is definitely the better option and the preferred method in most cases

Didn't spot your sig at first so I didn't do very well. Engage brain and then type

To engage my brain, first I have to find it. That doesn't get any easier with every passing year!!!

* It is perhaps worth pointing out that crimp connections are not without their issues. Provided they are made up correctly initially, they tend not to suffer the long term reliability problems that solder connections exhibit** but the correct use of the correct tool is crucially important. Ratchet crimp tools are infinitely better than the crude cheap crimp tools supplied with the cheap crimp kits but even they need to have the crimp pressure properly set up and I'm about to bin on of my ratchet crimp tools because it's not, even on the highest setting, applying enough pressure

The pre-insulated type connectors are not universally favoured (I know David of this parish doesn't like them for one) because you can't see the crimp itself. I do use them but every now and then I make a crimp on a bit of scrap wire and then cut off the insulation to check the function of the tool (hence the one that's going in the bin). They do however have the advantage of creating less of a hard joint (vis earlier discussion) as although there is obviously a hard edge at the end of the crimp itself, the ability of the cable to move is limited by the un-crimped insulating sleeve beyond that point.

(We found, through testing, back in my dim and distant that this was quite effective in reducing the potential for cable failure from the cable working at the hard point of the crimp. In fairness, I've never conducted similar testing on uninsulated crimps plus heatshrink. That method may well perform just as well or better but nobody is paying me overtime to spend several weeks of Saturday mornings, as Express Lifts did back when I was 18 or 19, making and destructive testing crimp connections. It was a bit boring but it didn't half boost my fag and beer money!)

** It is possibly further worth mentioning that a lot of the long term problems with solder joints in particular and wiring connections in general have only started coming to light, or possibly have only become more fully understood, in recent years. A particular example is wire creep in terminal connections and especially solder creep when the wired is twisted and tinned before being inserted in the connector

We would, in fact, have been summarily shot by our instructors back in my apprentice days for tinning a cable before making up a connection (it was strictly forbidden, and I do mean strictly - an instant quality control fail out on the shop floor) but that was because of the problem of solder wicking up the cable. It was not, at that time, understood (or certainly not widely know, even in the electrical industry) that solder would creep under pressure from a screw or plate terminal which, years later, results in a high resistance if not complete failure of the connection. It's only relatively recently that the use of bootlace ferrules on all stranded cables has come to be considered best practice as it turns out that even un-tinned stranded cable will creep over time

(I'll reiterate what an earlier poster said - we're talking here about the process of tinning, or applying solder, to a cable before making up a connection. This is not the same as tinned cable, preferred and indeed required by current standards for most marine work, where the individual strands have been tinned before the cable was laid)

Anyway, apologies for further witterings, it looks like it's going to be a sleepless night tonight as the dear lady wife is endeavouring to cough her lungs up (bless her, she is suffering) and I'm stressed up to the eyeballs with bloody soliicitors, estate agents, not to mention house buyers and sellers. Arses are being kicked on a daily basis 'cos we need the cash for the new boat asap!

 

[Bru]

edit add: worlds worst connector ever are 5 pin din.

Can't argue with that! Bloody awful design

 

[ghostlymoron]

A lot of choc blocs have plated steel screws which rot after a very short while. Also, the action of tightening the screw tends to part the strands of stranded wires which is why I prefer to use the type that has a screw down plate to retain the wire or a boot lace ferrule. The advantages of choc blocs are: readily available, simple to use, easy to re use with just a screw driver, don't introduce a rigid section in the line like soldered joints.

After reading this, I, for one, accept that tinning and soldering are not a good idea - and I've done both in the past.

Why are choc blocks worse than crimped connections, or those push-fit choc-block-like things?

 

[RichardS]

The fusebox, the negative busbar, and the barrier strip that connects the external runs to the wiring inside the enclosure, are all screw terminals with crimped forks on the wires.

Pete

Screw terminals = choc block (basically)

Richard

 

[Hydrozoan]

… a boot lace ferrule. …

Thanks, GM, that is what I meant by ‘crimped pin’. I presume one could use them, correctly sized, with the Wago and similar connectors, as well as with chocstrip. But I did not see the size needed for fine instrument cable in marine suppliers – are there tinned versions for marine use?

 

[prv]

Screw terminals = choc block (basically)

Possibly I used the wrong term. I mean connections like this:

used with either a fork or ring terminal crimped to the wire:

Pete

 

[Hydrozoan]

Possibly I used the wrong term. I mean connections like this ... used with either a fork or ring terminal crimped to the wire ...

Ah! Good - I thought that was what you meant and had been rather surprised by Richard's comment. But as I've shown, my connector vocabulary is not above reproach - though what else you'd call them I don't know.

 

[KellysEye]

>I have a additional sense that soldered joints on boats are discouraged as they add a level of brittleness into an harsh environment, vibration?

That's why you put a heat shrink cover on them, which I always did.

 

[prv]

Ah! Good - I thought that was what you meant and had been rather surprised by Richard's comment. But as I've shown, my connector vocabulary is not above reproach - though what else you'd call them I don't know.

To be fair, when I googled "screw terminal" to find the upper pic, the majority of the things it threw up looked like this:

...for which Richard's statement of "basically a choc block" makes sense.

I think the term is legitimately used for both kinds.

Pete

 

[lw395]

My oh my, what a lot of twisted knickers.

Can someone point me to this magic connectors, and what am I supposed to do with the 3 rolls of leaded solder?

Keep the leaded solder, it is still entirely legal to use it to repair stuff that was made with leaded solder, even in trade.
I believe there are other exemptions where it's allowed.
But these days, if you employ someone to solder with lead, they have to have 'hazardous materials training' and you have to take various precautions. So it's easier to generally stick to the Dolphin-Friendly stuff.
Which is a joke sometimes because the higher temperatures of lead free can mean you end up breathing all sorts of fumes fom flux, burning circuit board, melting cable etc etc.
To be fair a lot of other restrictions came in at the same time, so the cable is less likely to kill you with fumes as the sheath melts.
RS and loads of other places still sell tin/lead solder.

 

[Hydrozoan]

To be fair, when I googled "screw terminal" to find the upper pic, the majority of the things it threw up looked like this ... for which Richard's statement of "basically a choc block" makes sense.

I think the term is legitimately used for both kinds. .... Pete

Thanks, I see the point - but how then can one differentiate what are really quite different things within that general class of connectors? Perhaps an electrician here will explain.

 

[Capt. Clueless]

I'll go with the earlier suggestions of Wago's. We only sell them in boxes of 100 though.