Soldering Techniques

[wiggles]

This is purely a question to satisfy my curiosity.

I know that two methods of connecting wires that are considered permanent are crimps and soldering. There are a lot of posts about the former (with helpful suggestions) and very few about the later.

I have a lot of soldering experience in electronics but none or very little with heavier gauge wires. Also, with electronics, most connections tend to be soldered between PCB’s and components rather than wire to wire.

I can envisage how a sound soldering joint would be possible between say 2.5mm2 wire but I would like to know what techniques are used to connect larger (say 10mm2) cables?

Also, in terms of insulation presumably each conductor in a cable would insulated with heatshrink and then covered with one large piece of heatshrink which covers the whole cable?

From a mechanical strength point of view, when soldering cables, would it be better to offset the joins on the conductors – say 10mm so they are not all in the same place or would this make no difference?

RS, I’m sure you will have some educational pictures

 

[plugwash]

iirc the reccomended way of soldering thick solid wires is to put them next to each other and then bind them together with thin wire (say offcuts of phone cable or cat5) before soldering.

The tighter the wires are bound together before soldering the better the joint will be.

You will also need to be able to apply a lot of heat, a 25W iron just isn't going to be enough.

Remeber to insulate the joint appropriately after soldering.

 

[bernardgreen]

iirc the reccomended way of soldering thick solid wires is to put them next to each other and then bind them together with thin wire (say offcuts of phone cable or cat5) before soldering.

Some phone cable and most Cat 5 will NOT solder very well as they are not pure copper. Thin CPC from Twin and earth is better

And remember to put the insulation sleeve on one wire BEFORE soldering the joint and keep it cool otherwise it will shrink before you can slide it over the joint.

 

[plugwash]

I'd think the earth core from T&E would be too thick to use as an effective binding wire.

anyway the solder doesn't really need to stick very well to the binding wire, the binding wire is only there to hold the conductors in close proximity during soldering.

 

[TicklyT]

I believe tinned copper wire is available in appropriate gauges for binding.

I have successfully used single strands pulled from a bit of scrap flex to bind joints to be soldered in steel piano wire. I found single strand telecomms wire was a bit too thick to use for binding unless the joint was in 8SWG (about 3mm dia.) wire.

The binding wire contributes greatly to the mechanical strength of the soldered joint.

 

[plugwash]

I believe tinned copper wire is available in appropriate gauges for binding.

Indeed thats probablly the best bet, downside is you'd have to buy it specially.

 

[wiggles]

Thanks guys. Anyone know a supplier of this tinned copper wire for binding or any guidelines on what should be used for different wire sizes?

Any pictures or diagrams would be much appreciated.

 

[Norv]

You can buy it from RS Components. Heres a link (Dont know how to make the words 'RS Components' as a link)

http://rswww.com/cgi-bin/bv/rswww/s...cddaddlgkkgddlcefeceeldgondhgi.0&cacheID=ukie

 

[JohnD]

I think you can use Fusewire (still sold in old-fashioned hardware stores).

 

[tim west]

Large cables are sweated rather than soldered, the insulation is cut back sufficiently, special flux paste is applied to the joint as described above (splicing and tying together) then a gas torch is applied with care along with a stick of solder, wet rag or newspaper is used to clean any excess solder and keep the joint looking tidy. Large Lugs are done the same way as an alternative to hydraulic crimping.

 

[plugwash]

Whats the melting point of fusewire like? you don't want your binder melting when you try to solder it.

 

[holmslaw]

..

 

[ricicle]

Crimping or soldering is bodging.

I think you might be in the minority with that one

 

[holmslaw]

..

 

[RF Lighting]

So you honestly think that a screwed connection is more reliable than a soldered one?

The BS7671 permits inacessible crimped and soldered joints, but not inacessible screwed joints, but what do the IEE know

I agree that it is best to replace a cable, but it is not always practicable.