Advice on crimping from true leccy experts please

[salar]

When connecting very thin wires from a LED nav light to the "normal" sized wiring of about 1mm I am using a crimp connector, but there is hardly anything for the connector to grip on the thin wire. What is considered good practice? Is it OK to double back over the insulation and crimp that, or is there a pro method?

 

[Norman_E]

All I do with very thin wires is insert them into the same crimp as the thicker wire and crimp the lot together. Either use an "end to end" crimp or a normal one with a ring or spade end which I cut off and then insulate with heat shrink. If you must make the wires seperable cut a short piece of thicker wire to crimp in with the thin one.

I dont claim to be an expert but the method works and heat shrink taken so that it covers the crimp and about half an inch of the wires going in protects the thin wire against breakage where it comes out of the crimp.

 

[PaulRainbow]

When connecting very thin wires from a LED nav light to the "normal" sized wiring of about 1mm I am using a crimp connector, but there is hardly anything for the connector to grip on the thin wire. What is considered good practice? Is it OK to double back over the insulation and crimp that, or is there a pro method?

Not in my book. It's OK to double the conductor though. I would use glue lined, heat shrink butt crimps. These will not only give you a waterproof seal, but they will give additional support to the thinner wires. For added support you could add some heat shrink over the two/three thin wires too . (heat shrink over all wires together), safety in numbers

 

[salar]

Thank you, two ideas in about as many minutes!

 

[boatmike]

Not in my book. It's OK to double the conductor though. I would use glue lined, heat shrink butt crimps. These will not only give you a waterproof seal, but they will give additional support to the thinner wires. For added support you could add some heat shrink over the two/three thin wires too . (heat shrink over all wires together), safety in numbers

I agree of course but if you are talking about NMEA signal wires my usual practice has always been to bare twice the required length double over and tin the doubled end with electrical solder before connecting. If you have a whole bunch of them (like connecting a radar etc) Its good to have a proper connecting box that will support the incoming and outgoing cables so that there is no stress on the connection itself. Failing that I agree with Paul about heat shrink or even a liberal binding of insulating tape (less tidy of course) Don't just leave the connection hanging in the air with no support!

 

[anoccasionalyachtsman]

Again, possibly not best practise but I've used a short length of solder wire to help fill the oversized hole. Crimps very nicely.

 

[Poignard]

What I do is to fit the correct sized crimped bootlace ferrules to the wires and connect them using a terminal box.

 

[Lon nan Gruagach]

I agree of course but if you are talking about NMEA signal wires my usual practice has always been to bare twice the required length double over and tin the doubled end with electrical solder before connecting. If you have a whole bunch of them (like connecting a radar etc) Its good to have a proper connecting box that will support the incoming and outgoing cables so that there is no stress on the connection itself. Failing that I agree with Paul about heat shrink or even a liberal binding of insulating tape (less tidy of course) Don't just leave the connection hanging in the air with no support!

Again, possibly not best practise but I've used a short length of solder wire to help fill the oversized hole. Crimps very nicely.

I learnt that you should never ever allow solder to enter a crimped joint. It so malleable that over time it will flow out of the joint reducing pressure on the conductor and lead to a fail.

 

[oldmanofthehills]

I agree of course but if you are talking about NMEA signal wires my usual practice has always been to bare twice the required length double over and tin the doubled end with electrical solder before connecting. If you have a whole bunch of them (like connecting a radar etc) Its good to have a proper connecting box that will support the incoming and outgoing cables so that there is no stress on the connection itself. Failing that I agree with Paul about heat shrink or even a liberal binding of insulating tape (less tidy of course) Don't just leave the connection hanging in the air with no support!

If you go to the trouble of tinning the wire on site, why not just solder the wires together, and then insulate with sleeving (or as its low voltage even insulating tape) ? Much better than a crimp particularly for connections with very low currents and thus increased vulnerability to high resistance connections. Seawater can cause nasty corrosion in connections thus causing high resistance, and gets to many areas of boat where it shouldn't.

Of course if you can only reasonably tin wire end off site you still need a crimp, but tinning ends will help

 

[PaulRainbow]

If you go to the trouble of tinning the wire on site, why not just solder the wires together, and then insulate with sleeving (or as its low voltage even insulating tape) ? Much better than a crimp particularly for connections with very low currents and thus increased vulnerability to high resistance connections. Seawater can cause nasty corrosion in connections thus causing high resistance, and gets to many areas of boat where it shouldn't.

Indeed, but you suggest soldering an wrapping in insulating tape, on a nav light that's obviously going to be out in the elements. There is never, ever, an excuse for wrapping soldered wires in insulating tape.

Of course if you can only reasonably tin wire end off site you still need a crimp, but tinning ends will help

See post #8

You either crimp or you solder, not both.

 

[lw395]

[/COLOR]Indeed, but you suggest soldering an wrapping in insulating tape, on a nav light that's obviously going to be out in the elements. There is never, ever, an excuse for wrapping soldered wires in insulating tape.



See post #8

You either crimp or you solder, not both.

Self-amalgamating tape perhaps, if you have to....
Tinning before crimping is a bodge.

If you solder after 'crimping' you probably haven't really crimped the joint. A properly done crimp has no gaps that solder will run into. If you just squeeze the connector on to the wire so it stays put while you solder it, that's not crimped, that's soldered.

The OP's idea of crimping onto the plastic insulation is absolutely wrong. Crimping works at enough pressure to move copper around, A wodge of plastic in there will prevent that.

Get connectors appropriate for the wires.
Small wires, strain relief is important, they will be vulnerable to breaking whether crimped or soldered if under any stress. Crimps which have a secondary grip which holds the insulation help.

 

[oldmanofthehills]

[/COLOR]Indeed, but you suggest soldering an wrapping in insulating tape, on a nav light that's obviously going to be out in the elements. There is never, ever, an excuse for wrapping soldered wires in insulating tape. See post #8.

You may not work on a boat at sea much. I have soldering iron and insulating tape aboard. I can always re-solder damaged connections but may not have crimps or shrink sheathing to hand halfway across the Irish sea. Insulating tape is not ideal but …...

.[/QUOTE]You either crimp or you solder, not both.[/QUOTE]

Interestingly clamped connections are often tinned, and there is no known issue in clamping or indeed crimping pre-tinned wires or wires as supplied with various items. Maybe it depends on whether it is just tinned or "blobbed" with solder

 

[Lon nan Gruagach]

You clearly don't work on a boat at sea much. I have soldering iron and insulating tape aboard. I can always re-solder damaged connections but may not have crimps or shrink sheathing the hand. Insulating tape is not ideal but …...


.

You either crimp or you solder, not both.[/QUOTE]

Interestingly clamped connections are often tinned, and there is no known issue in clamping or indeed crimping pre-tinned connections as supplied with various items. Maybe it depends on whether it is just tinned or "blobbed" with solder[/QUOTE]

Pre tinned wire will have virtually no free solder on it, the bulk of the surface being the copper/solder amalgam. Tinned stranded wire will have been tinned before plying. It is not possible to reproduce this without separating all the strands.

 

[noelex]

Both crimping and soldering can produce good marine connections.

With fine wires soldering and then protecting the joint with glue lined heat shrink is my preferred option.

 

[boatmike]

You either crimp or you solder, not both.

Interestingly clamped connections are often tinned, and there is no known issue in clamping or indeed crimping pre-tinned connections as supplied with various items. Maybe it depends on whether it is just tinned or "blobbed" with solder[/QUOTE]

Pre tinned wire will have virtually no free solder on it, the bulk of the surface being the copper/solder amalgam. Tinned stranded wire will have been tinned before plying. It is not possible to reproduce this without separating all the strands.[/QUOTE]

Well I must say that although I usually agree with Paul Rainbow on most things I agree with you that most electrical equipment I have had supplied that needed to be connected to a clamp, screw, or crimp terminal had tinned ends. It is IMO important to avoid damaging the wires when clamped to do so especially when using the dreaded "chocolate box" connectors. Crimp connectors less so but the original post was about connecting unequal wires and in particular very fine signal cables used for NMEA connections which are easily damaged or broken. Frankly I have always preferred to solder these direct but if they are required to be removable like for instance a radar cable going through a deck fitting where you need to remove it to take the mast down I think you will find that most manufacturers tin the wire ends as originally supplied.

 

[rszemeti]

Tinned (as in all the wires stuck together with solder, rather than individual wires coated in solder) is a no-no as it almost always fractures just where the wire transitions from "tinned" to "free" ... you won't find it on planes, and you won't find me doing it on boats.

If your crimp will not effectively hold on the wire, or a "doubled up" wire, then you are using the wrong size crimp!

 

[Ceirwan]

Tinned (as in all the wires stuck together with solder, rather than individual wires coated in solder) is a no-no as it almost always fractures just where the wire transitions from "tinned" to "free" ... you won't find it on planes, and you won't find me doing it on boats.

If your crimp will not effectively hold on the wire, or a "doubled up" wire, then you are using the wrong size crimp!

I think the problem here is going between 2 different wire thicknesses. At a guess the supply wiring will be 1.5mm maybe 2 or 2.5mm. These cheap nav LEDs (and maybe the expensive ones as well, I don't know as I only ever got the cheap ones) have absolutely tiny wires, so any crimp that's suitable for one diameter will probably not fit the other.

I used open barrel crimps on mine, followed by two layers of adhesive lined heat-shrink.
Handy guide on how to use them here: https://www.youtube.com/watch?v=cWkLgkqMVfY

 

[seadog30]

What I do is to fit the correct sized crimped bootlace ferrules to the wires and connect them using a terminal box.

+1

This is the way we had to connect on high reliability connections such as rail electronics and defence products.

Regards

 

[PaulRainbow]

+1

This is the way we had to connect on high reliability connections such as rail electronics and defence products.

Regards

Would you do this to fit a nav light ? Where would you fit the terminal box on a sailboat, in the mast or on the outside ?

 

[rszemeti]

I think the problem here is going between 2 different wire thicknesses. At a guess the supply wiring will be 1.5mm maybe 2 or 2.5mm. These cheap nav LEDs (and maybe the expensive ones as well, I don't know as I only ever got the cheap ones) have absolutely tiny wires, so any crimp that's suitable for one diameter will probably not fit the other.

Crimp a bootlace ferrule of the correct size onto the thinner wire, crimp the ferrule into a larger crimp that fits the larger wire?

As you rightly say, when going up/down wire sizes, a bit of heatshrink does wonders for strain relief and protecting the thinner wire.