Extending cable, soldering method

[markwm]

I need to cut into some 2.5mm cable to extend it. I'm not a big fan of crimp joints and would prefer to solder.

Regarding insulting the joints, is shrink wrap the only way to go as opposed to insulation tape?

 

[ban-all-sheds]

I need to cut into some 2.5mm cable to extend it.

Why?

I'm not a big fan of crimp joints

Why?

and would prefer to solder.

Why?

Regarding insulting the joints, is shrink wrap the only way to go as opposed to insulation tape?

No, you could also call them ugly and smelly, and suggest they are lacking in the manhood department.

 

[ban-all-sheds]

But seriously...

1) Try to replace sections of cable, not cut'n'shut.


2) Nothing wrong with crimping, soldering worse, not better. Does your lack of admiration stem from using the wrong tool?

You need one like this:

not one like this:

If you really, really, really, really must solder: http://www.markhellerelectric.com/solder.pdf


3) "Insulating tape" starts out not being the former, and then falls off.

 

[PrinceofDarkness]

I suppose you mean that this joint would be inaccesible? This situation ought to be avoided if possible, but if not so, then I approve of your preference for a soldered joint rather than a crimp.

A soldering iron in the hands of a competent person is so much more reliable than a pair of crimping pliers in the hands of an inexperienced dolt using an inappropriate crimp not suitable to the type of cable core.

Yes, you can 'insult' the soldered joint using decent quality PVC insulating tape using at least three layers - provided that you use a mini-cable tie at each end of the tape, to stop it unravelling when it becomes tired.......


Lucia.

 

[ColJack]

coloured tape is NOT insulation tape, it's phase identification tape and should only be used as a top layer AFTER you use proper insulating tape, preferably self amalgamating tape..

 

[PrinceofDarkness]

You're the first to mention 'coloured' tape, Coljack. Others here have referred only to insulating tape.

So what's your point - are you saying that insulation tape is colourless?


Lucia.

 

[ColJack]

if you want to be picky, there's no such thing as "colourless", everything has colour as colour is a function of reflected and absorbed light..
if something is "colourless" then it's invisible as it would reflect no light at all..

but you're right, no one has mentioned coloured PVC tape, but the general misconception is that all of the coloured PVC tapes sold as "insulation tape" are actually insulating tape.

while many insulating tapes are indeed coloured, not all coloured tapes are insulationg, at least not to the required specifications..

 

[ColJack]

ok, now I'm scared...

while googling for "insulation tape" I found out that they have "nuclear grade" gaffer tape..

it's not filling me with comfort to know that they need their own grade of gaffer tape to hold the reactor together..

 

[markwm]

I don't like crimps because it's just a personal thing in that I don't think they feel as permanent as a soldered joint.

I've had our electrician do them before and I've tried myself(not live) and there always seems to be a tiny tiny little bit of play in the joint.

I have done soldered joints before myself, I hooked the cables together, nipped them tight with plyers, heated the cable with a mini gas soldering iron, then applied solder. I did use heat shrink that time but just wondered if insulation tape would do.

Once the 3 individual cables have been insulated, should you also group them together with tape??

 

[PrinceofDarkness]

There's no need for pliers, Mark - and certainly no need for twisting the wires together prior to soldering. The wires should be laid alongside each other and bound together with tinned wire (eg, fuse wire) and then soldered. This will give you the strongest possible joint.

If you're soldering or crimping insulated and sheathed cables, and the joint is to be inaccessible, then you have to restore the full insulation including the jacket.
I've lost count of the number of poorly made crimped joints that I've seen where no attempt has been made to restore the outer sheath insulation.


Lucia.

 

[mikhailfaradayski]

I don't like crimps because it's just a personal thing in that I don't think they feel as permanent as a soldered joint.

fair dos, everyone is entitled to their own preferred method, so long as it works adequately. However, correctly crimped joints are very strong indeed. So strong they are approved by aircraft manufacturers (both civil and military) railway rolling stock (both for surface and underground) In those examples, the failure of a joint could potentially result in lost lives. Plane lands too abruptly(like a stone), tube train catches fire in a tunnel - both disasterous consequences. If its good enough for them, surely its good enough for a bit of T+E that will be fixed and buried in plaster.

I've had our electrician do them before and I've tried myself(not live) and there always seems to be a tiny tiny little bit of play in the joint.

how much stress did you apply to find that bit of play? MOre than the joint would ever experience whilst in service?

I have done soldered joints before myself, I hooked the cables together, nipped them tight with plyers, heated the cable with a mini gas soldering iron, then applied solder. I did use heat shrink that time but just wondered if insulation tape would do.

Other than for a temporary repairs (mainly to get machines back into production) i only ever really consider insulation tape to be a tool, not a material. Even though the name of the stuff would seem to contradict that. H/shrink is far better (the stuff with the glue lining is best IMO)

Once the 3 individual cables have been insulated, should you also group them together with tape??

As others have suggested, this should be avoided if possible by replacing the whole of the defective section if at all possible, but if you really do need to do it this way, use the tape to build up the insulation back to original dimensions.

FWIW, when splicing cables, i used to stagger the individual joints so they look neater and will give a stronger result.

 

[holmslaw]

..

 

[1john]

If you have twisted conductors together you have stretched them therefore you have made the csa smaller and the cable cannot carry it's maximum design current, I would consider a twisted soldered joint to be a poor connection and an area of failure.

Correctly sized and quality crimps with a good ratchet crimper are the way forward. Self amalgamating tape is also preferred over insulation tape and it you cannot get large enough shrink wrap. In general, insulation tape doesnt require a tool to remove it as it can be unwound, self amalgamating tape requires to be cut away to remove it.

 

[empip]

23 posts on the question, re. Marine connections ...
http://www.sailnet.com/forums/gear-maintenance/40595-crimping-versus-soldering.html

Little bit of everything at Terminal Town -
http://www.terminaltown.com/Pages/Page7.html

More here... http://www.pbase.com/mainecruising/wire_termination&page=1
p.2 double crimp ratchet tool -- Side to side and top to bottom orientation of insulated crimp...
Side to side ...

Top to bottom...

... Advice is, to position barrel split at top.

-0-

 

[ColJack]

If you have twisted conductors together you have stretched them therefore you have made the csa smaller and the cable cannot carry it's maximum design current, I would consider a twisted soldered joint to be a poor connection and an area of failure.

he doesn't say he twisted the wires together, and even if he did, unless he's soldering round end to round end, then the contact surface when soldered is going to be a lot more than the CSA of the wire..

nothing at all wrong with a correctly made soldered joint, but most of us don't know how to do it properly nowadays since we are all used to the faster and easier way of using crimps..