A strange wiring phenomenon

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Portsladepete

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Some of my layout is wired with a fairly hefty gauge wire which leads into my home made switch box, (waterproof), I have found that the wire that has been outside for 2-3 months does not take solder well at all, this is despite flux and a 100 watt soldering gun.
To discount the outside temperature I removed a section, stripped where the copper was nice and bright, but the result is the same. Using the some of the wire that has been indoors, no problem even with my 30 watt iron.
The wire is multi strand heavy duty speaker wire, do you think this is the problem? Having worked outdoors on vehicles for over 30 years, never came across this before.
 
Oxidization !
 
Are the wire strands tinned, or bare copper? - I assume it is not 'oxygen-free'? :rofl::rofl::rofl:

My guess:
The core is many-many very-fine strands? - These will have an enormous surface-area, compared to a single, thick, core. All this surface will be very-slightly oxidised, so there will be a large area of 'dirty' copper to deal with..

Try stripping a good inch of cable. Use a fine wire-brush (failing this, either wire-wool, or emery) work the brush from insulation to tip of wire. One direction away from the insulation. Rotate the wire a little and repeat.. pull-through a bit of tissue, or lint-free cloth. Twist up the core. Lightly flux (your flux is for electronics, and not brass/plumbing, isn't it?) and try that.

PhilP.
 
Yeah, if you think about it, a plumber when soldering a copper joint, even a Yorkshire fitting, will wipe the end of the pipe with wire wool and then use a separate flux.

I don't think the separate flux is an issue, although I prefer them to the resin core, just a personal thing - but wiping the pipe is what does the trick :nod::nod:
 
Wire is bare copper, about 8-10 strands, roughly similar to household 15 amp, flux is for electrical as is the solder.
The same wire kept indoors solders easily, the piece I cut out was about 18 inches long, one end I stripped about an inch back from the cut was fine, the other end, same procedure ,no way!
Maybe the wire is to blame
 
PVC insulation is not 'gas-tight' so oxidation will occur over time..

The wire will 'age' (oxidation again) over-time, so thirty year old wire from my Dad's workshop, is a PITA to solder!

Where was the wire manufactured? - Quality of the copper used..


Be VERY careful with fluxes used.. If it is at all aggressive, it will need cleaning off after the job is done. - If not, the wire will 'disappear' over time.
 
Portsladepete said:
Wire is bare copper, about 8-10 strands, roughly similar to household 15 amp, flux is for electrical as is the solder.
The same wire kept indoors solders easily, the piece I cut out was about 18 inches long, one end I stripped about an inch back from the cut was fine, the other end, same procedure ,no way!
Maybe the wire is to blame
Click to expand...
It may be a lot of things in one - although I'm not a fan of speaker wire because you can get cheap and nasty stuff. It may be the oxidation and the temperature.

Do you have any separate flux, the stuff used for lower melt solder on brass, say? Philp will give you the warning about not using it on printed circuit boards, and you're meant to wash the finished piece after use because of the corrosive qualities, but in the right circumstances it works a treat, especially when working with some copper wires.
 
Portsladepete said:
Some of my layout is wired with a fairly hefty gauge wire which leads into my home made switch box, (waterproof), I have found that the wire that has been outside for 2-3 months does not take solder well at all, this is despite flux and a 100 watt soldering gun.
To discount the outside temperature I removed a section, stripped where the copper was nice and bright, but the result is the same. Using the some of the wire that has been indoors, no problem even with my 30 watt iron.
The wire is multi strand heavy duty speaker wire, do you think this is the problem? Having worked outdoors on vehicles for over 30 years, never came across this before.
Click to expand...
Some manufacturers have been reducing costs on multistrand speaker cable and instrumentation cable by using an aluminium or steel core and copper plating it. Works OK for high frequency signals but is rubbish for high current use. Also copper plating will not last long outside and the wire will then be very difficult to solder. Maybe you have used some of this cable.
Peter
 
That sounds like it, bought from a local Screw. fix, cos it was so cheap, 25 metres for 2 packets of crisps , yet again my mean tight wad nature has come back to bite me.
If it fails I will replace with the 10 packets of crisps stuff, Thanks gents, meanwhile my grand alpine slope is installed and all the locos manage it, with my limited amount of stock.
 

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And did you know that pasta do lutowania is Polish for solder (cheap) paste? I’m not that much of a tight wad really, it’s just that my preferred prices are based on pre decimalisation, it’s best if I don’t go into supermarkets etc, bar of chocolate at 15 shillings !!!
 
So, it is not uncommon for moisture and air to work a ways "under" insulation. Remember that the strands are round.

Take a package of canned food or soda, notice the nice big spaces between the cans?

So, that may be part of it. Cut about 6" off the wire end, then strip and see if your solder takes.

Also, it is also true as already stated, thank in the search to sell a cheaper product, some wire is plated which can go bad also.

I use very coarse stranded wire outside, since the thin strands can oxidize away so quickly they turn to dust in some situations (mine get water every day).

you could also solder a short length of solid wire to the end of the stranded, and then fully encapsulate the solder joint, with liquid rubber, or perhaps well-sized heat shrink (but since your wire is 2 conductor "zip" wire, the separate wires are NOT perfectly round, and do not seal perfectly with heat shrink all the time).

Greg
 
Being of scientific curiosity I tried holding the gun to the wire for an extended period, the copper colour was replaced by a very steel like colour.
Looks like peterexmouth was right, it does seem that my bargain wire was not.
I worked on vehicle’s wiring that was exposed for years to the outside, any deterioration was to the insulation hardening etc, the only wire faults were caused by dissimilar metal contact etc, or excessive current draw.
Anyway, the speaker wire is going to be replaced as and when, luckily my layout is small.
 
Mechanical connection - 'Choc-Block' and the like, may buy you some extra time?

PhilP.
 
Portsladepete said:
Being of scientific curiosity I tried holding the gun to the wire for an extended period, the copper colour was replaced by a very steel like colour.
Looks like peterexmouth was right, it does seem that my bargain wire was not.
I worked on vehicle’s wiring that was exposed for years to the outside, any deterioration was to the insulation hardening etc, the only wire faults were caused by dissimilar metal contact etc, or excessive current draw.
Anyway, the speaker wire is going to be replaced as and when, luckily my layout is small.
Click to expand...
Marine cable is good for external use - you'll only get it from Chandlers and surprisingly, it only comes in US sizes /codes. If you're going to wire a boat, it's the only stuff to use - even UK auto wire isn't up to the task :shake::shake::shake:
 
I used some 40 year old 18 awg speaker wire for one set of sensor leads on my reverse loop module. The zip-cord wire insulation was clear and the multi-strand conductors were differentiated by one being tinned copper and the other bare. I had no trouble soldering a lug onto the tinned conductor. Trying to solder a lug to the bare conductor was a whole different animal! The bare conductor was obviously well oxidized. It was dark brown instead of a bright copper color. I ended up cutting the wire back almost a foot to get to wire that could be soldered. Even then it took alot more heat and flux than the tinned conductor.
I have had pretty good results using an AMTECH paste flux NC-559-ASM for electrical/electronic applications. I've tried a liquid rosin flux from GC electronics but the AMTECH paste works much better for me.
 
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