I'm very confused (tinned wire v silver solder applied to the ends)

M

mortehoe

Well-Known Member
Joined
19 Sep 2006
Messages
290
Visit site
I\'m very confused (tinned wire v silver solder applied to the ends)

If you take 2 core standard domestic copper multistrand wire and use it on your boat and 'tin' each end of the wire with non-acidic fluxed silver solder is there any difference between that and fully tinned wire when the strands of the domestic wire go completely black????? ( ie will there be any difference in the resistance between the power supply and the appliance? Sorry to be a pain, but a drum of tinned wire is more than muy caro for a test that whose results should be common knowledge to us all .... And I haven't a clue!!!)

Cheers /forums/images/graemlins/smile.gif
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

I could be talking complete bow-locks but I'm sure that I read somewhere that the current actually travels along the surface of the wire rather than through the middle of it. If that is the case then I am sure that oxidization must have a detrimental effect.

As I said though, my little grey cells are not what they used to be and I may have mis-remembered.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

You can tin the ends with soft solder, but silver solder is quite different. The lowest melting point silver solder in my workshop is a cadmium bearing alloy with a melting point of between 680 & 720 Celcius, others vary up to about 900 degrees C. All of these require far too much heat for use with electric cable unless you want to melt all of the insulation.

In answer to your question, copper seems to turn black when exposed to sea water. If you can keep it completely dry you should not have any problems, but on a boat wiring often seems to get routed where it will get wet. The black colour indicates oxidisation, so resistance will increase, but the amount of increase may not be critical if the wiring was adequately sized in the first place. My own experience of this is a through hull transducer fitted with ordinary copper flex sealed in to the unit and not replaceable. It still works even though it is black from the transducer to the point a yard away where I cut it and joined in a new cable.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

If its nice clean new untinned wire,the solder will resist the negative corrosion, in the ideal world fully tinned wire is best. Pesonally I use untinned wire crimp the connector on then flood the joint with solder. In heavy engineering this crimp and solder is a common method,have experienced hot crimps without the solder so for the type of voltage/currents us boaties use this method will last for a long time, hope that this does not confuse you further.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

=======================================
I could be talking complete bow-locks but I'm sure that I read
somewhere that the current actually travels along the surface of the wire rather than through the middle of it. If that is the case then I am sure that oxidization must have a detrimental effect.
=======================================


This is true at RF frequencies and why on ships the antenna leads from the radio room were copper tubing. This is not the case with DC where the current utilises the full cross section.


John
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

You will find that the blackening if the copper extends well up inside the insulation but it has never amounted to what I would call corrosion hence my challenge elsewhere to the need to used tinned wire on the average family yacht. A dollop of silicone grease on the wire end should stop it but it will frustrate any future efforts to tin the ends.

However it is not silver solder that you will be tinning the ends with as it has silver solders have rather high melting points and I doubt if you could do it without melting too much of the insulation. If, like me, you like the idea of tinning the wire ends then use the same ordinary tin/lead solder that you would use for electronics wiring or circuit boards. Tinning the ends keeps all the little strands together as well.


Looks like I am the slowest typist on the forum
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

You should be aware that cable ends tinned with tin/lead solder and then crimped or fastened using 'chocolate block' will work loose as the solder will creep under pressure.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

As others have said, silver solder has a very high melting point, and requires some kind of flame to apply. This heat would damage the insulation and negate the whole process.

Tinning the ends with ordinary solder makes the end brittle, and with the vibration on board a yacht, could eventually lead to failure.

Far better, in my opinion, to use crimped connections, PROVIDED THAT THE CORRECT CRIMPING TOOL IS USED. These ones that look like a pair of pliers are as much use as a chocolate teapot. Invest in a proper ratchet crimping tool.

Again as already stated, the problem is a salt-laden atmosphere. I use either silicon grease or silicon spray over the connections to keep the moisture out.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

I am not certain that the blacking of the cable is totaly due to salt. Of the panel we get back for referb some wires are black, but the majority are not. It seems related to if the circuit is powered up in normal use. Thus we find three circuits will have copper wire, then a couple of blackened wires, then back to clean copper cables.
So it may be an electro plating effect, or electro/chemical, but does not look like corrossion.

Brian
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

I would agree with you there, Brian. Some of the effect must be due to (excess ?) load as well as electro plating or electro/chemical effects. Probably made worse by DC systems.

Jim
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends

We've had a couple of F1 mechanics at the cottage and both said that they crimp connections on F1 cars to avoid vibration breakages that occur with soldered joints.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

The blacking is caused by if I remember correctly by the loss of 1 negative neutron when power is applied and is known as Negative conductor corrosion and is not caused by the salt laden air. Im not a scientist,just an artisan in the electrical field. I forgot to mention in my post that all of my looms are laced Admiralty pattern and hence have not suffered from mechanical failure due to vibration, the only time that I have seen a silver soldered connection was a "Get her out quick" attitude by a Spanish ship yard, that cable sheared off in three weeks disabling the generator.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

This is something that happens with any moisture, salty or otherwise.

The black is Cupric oxide (black copper oxide).

The moisture is wicked up the cable (maybe for several metres) by capillary action.

Use tinned wire as this protects the copper core of each strand.

Things are maybe ok in low current cabling i.e sensors, but higher currentr cables may cause high resistance in a joint, that equals volt drop & heat.

If you use cable & tin the ends & then crimp or insert into a screw connector then the solder may cold flow & cause a loose connection + a stress point where the solid, soldered end finishes.

Why not use a common trick, coat the wire & fill the connector with vaseline or petroleum jelly & then crimp or screw ?

This keeps moisture out of the joint & stops it wicking up the cable.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

if tightened and soldered properly a soldered joint will not come loose, think of a soldered joint in an armature, this is revolving at many thousands of revs and they dont come loose!!I had many years as an armature winder and I never found a soldered joint come loose.Dont use solder used by plumbers there is too much lead in it and it wont flow up the conductors, you want a high tin content solder usually called 60/40. Over many years I would always prefer a soldered joint to a crimped.I have never seen a soldered joint fail (if done properly) but I have seen crimped ones.As previously mentioned silver solder has too high a melting point.It doesnt hurt to spray your connections with something like WD40.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends)

Presently the industry is switching/has switched(?) to lead-free solder. One of these alloys contains about 2.5% silver, some copper and tin. Melting point a little higher than the old 60/40 Tin Lead. This may have been called silver solder leading to the confusion with silver hard solder an alloy of silver and copper.
Google for lead free soldering will give plenty of info on this.
Theo.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends

In practical terms for a small yacht while tinned wire is better ordinary copper wire can be used. However crimp or solder the connections.
make sure all wiring is in tubular conduit so that it can be easily replaced and expect to replace the wire after a few years. Obviously using heavier wire than necessary with less strands willl make it last longer and grease or simmilar will help keep the moisture out.
Once that black corrosion has entered the wire you can not reconnect the wire if you get a fault. Just throw it away.
So not the best practice but it seems to be what I do. olewill
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends

I also always solder and crimp. Solder does not make the wire 'brittle' and does improve the mechanical and electrical properties of the join. However it does create a weakened 'hard point' where the solder ends and solderless wire continues. For this reason I encase the lot in adhesive-lined heat shrink.

PS. DC does indeed tend to run up the outside of a cable, but that does not mean that an outer layer of gunge creates significant resistance. It is only at joints that it really matters.
 
Re: I\'m very confused (tinned wire v silver solder applied to the ends

I recently re-wired a 1972 boat which had been wired throughout with plain copper stranded household wire. I found that in most cases the wire had corroded far into the length and I believe this was due to atmospheric moisture tracking up the interstices between the copper strands. The best solutions are (a) use a tinned or silvered strand if you need flexibility, or (b) use a solid conductor where you don't.

However, I think both of these methods are just delaying the inevitable in the marine environment (salt spray is deemed by the MoD to be top of the list of corrosive agents).

When using stranded conductors it's good practice to tin the end of the cable as far back as the sheath to try and seal up the intersticial paths, and to seal the area between this tinned end and the sheath with something like silicone sealer or printed circuit board lacquer. The idea is to stop moisture getting in.

Most of the joints I made were soldered (and covered with heatshrink) because I don't like crimps that aren't made with a calibrated tool; however, I admit I've had to come away from that ideal in many cases. Someone has suggested soldering after crimping which sounds good.

I personally also think chocolate blocks are the absolute worst things ever invented due to the coarse threads in an environment where there is constant low frequency vibration. Some work loose, and it constantly amazes me that they don't all work loose all the time. If you have to use them, use them only on services that are not vital.

But your original question was about resistance changes and I don't think this should be an issue. If there is a resistance change it's going to be minimal and unnoticable unless you get to the point where the joint is imminently going to fail.
 
Many tks for all the input - I got the solder wrong!

What a learning curve about something I though that I knew something about, and soon found out that I was totally out of date!!!!

The solder that I was referring to was Maplins 'Lead Free Silver Solder' 4% Ag 95.5% Sn 0.5% Cu with a melting point of 217*C Quote from Maplins Catalogue: "The high Ag content improves the conductivity and lowers the melting point, improving the flow."

The 2nd Maplins solder that I used to use is 99.3 Sn/ 0.7% Cu with a melting point of 227*C.

The other solders that I use are Bernzomatic 'Silver Bearing Lead Free Solder' for plumbing and it has a melting point of 255-260*C and an old 1/8" solder, possibly Pb/Sn 183*C

I didn't realise that when I said 'silver solder' you all thought I was referring to brazing solder. Sorry, I should have googled 'silver solder' before I wrote it down!!!!

Anyway, having Gooogled away and digested most everything on 'lead free solder and soldering' it seems to be that ideally tinned wired should be use OR fresh/non-oxidised domestic multi strand or solid core can be used with rosen-fluxed low temperature lead-free solder to 'tin' ends. It doesn't seem to matter if the wire strands go black beyond the solder tip as long as the mechanical joints are made properly with say a 0.4-0.6 or less Ohm resistance say across 3m for 1.2mm^2 wire.

I'm basically rewiring the boat - It's a complete mess at present with really strange voltage drops (upto -0.4V) across joints less than a metre apart!

I'm connecting into mainly terminal blocks (brass screws) and occasionally will be using galvanised (?) crimps crimped with a ratchet crimper. All mechanical joints will be coated with vaseline or Boeshield depending on accessibility/idleness etc.

My worst problem seems to be that the copper wire (single core, 12 strands, ~2mm^2) that goes from the engine gearbox to the external anode (2m) vibrates and snaps off inside the insulation about every 8 months. I don't know whether I should be using starter motor cable .... mind you the starter motor cable snaps off at it's crimped joint every other year as well in spite of the anti-vibration loop. I might as well just bite the bullet and replace the engine/anode cable annually.

I agree that multi-strand wire which has sat on the boat for several years and has gone completely black (over 15m!) is wire now only fit for the skip. Solid core wire can be cleaned and tinned ....

So all in all, the best solution and cheapest long term solution would be to strip out all the non-marine wire (ie auto or domestic) and replace it with genuine marine tinned wire .... So I'd better start saving.

Many thanks for the info and advice /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif
 
Re: Many tks for all the input - I got the solder wrong!

This whole thing is about a ha'porth of tar. If A is better than B, and you can afford the difference, surely the question is a no-brainer?

/forums/images/graemlins/tongue.gif
 
You must log in or register to reply here.

Share this page

Top