I came across (somewhere) a reference to a (seemingly) small splice connector to break out from a wiring run, but of course I didn't bookmark it and now can't find the reference. They were referenced in someones blog about layout building (I believe). They were blue but the only blue ones I can find seem a little on the big side. Does anyone have any ideas?
I think in the US they are called suitcase connectors?
If it is solderless splices then search terms such as "T tap", "quick splice" or "Scotchlok" might turn something up. The smallest I've seen is 18-22 AWG (roughly 0.5 mm2), e.g.
https://www.ebay.co.uk/itm/120-60PCS-Quick-Splice-Scotch-Lock-T-Tap-Wire-Crimp-Cable-Terminals-Connectors/373117835458?hash=item56df8e58c2:g:~KQAAOSwMYVfEUx9 (https://www.ebay.co.uk/itm/120-60PCS-Quick-Splice-Scotch-Lock-T-Tap-Wire-Crimp-Cable-Terminals-Connectors/373117835458?hash=item56df8e58c2:g:~KQAAOSwMYVfEUx9)
This sort of connector has various trade or brand names, but the generic term for them is "insulation displacement connectors", or IDC's for short, because when you close them around the wire they cut through the insulation and part of the cable inside it.
I've never liked using them because to my mind cutting partway through a cable reduces its strength and increases the possibility of the cable snapping in half, I also think that there is a risk of the blade cutting too deeply into the wire and adversely affecting the integrity of the circuit that I'm tapping into.
Personally, I've always regarded them a lazy man's way of tapping into a circuit and much preferred to cut the cable and use a proper terminal block or a soldered connection.
Thanks Peter, I consider my wrist firmly slapped 8) :o
Whether or not there is a theoretical risk of cable damage does not change the fact that IDCs are almost universally used in everything from computers to mains wiring.
Used properly, the junction is a cold weld and is safer and more reliable than a screw-down connection, potentially reducing fire risk in current carrying applications. One of the worst forms of connection is where well-meaning people solder the strands of multi-strand wire before inserting it into a screw terminal. The solder will creep and flow over time loosening the join. If it is desirable that the individual wires are held together, a bootlace ferrule should be used. If soldering is the only option to prevent fraying then only the very tip should be soldered so the screw down connection is made on the unsoldered wires.
Quote from: GraemeD on January 16, 2021, 18:40
The solder will creep and flow over time...
You learn something new every day* - never knew solder crept with time. Thanks for the warning.
David.
*hopefully!
Some good points have been made about connecting cables together.
I think the most important thing when doing so is to consider the current the cable is carrying and where the cable is being used then selecting the most suitable jointing method.
Quote from: clayliner on January 16, 2021, 18:55
Quote from: GraemeD on January 16, 2021, 18:40
The solder will creep and flow over time...
You learn something new every day* - never knew solder crept with time. Thanks for the warning.
David.
*hopefully!
Yes, when wires are twisted together before putting into a screw terminal they will retain some 'springiness' but when 'tinned' and soldered together into a mass then over time the solder will 'smoosh' (if there is such a word) and the contact will become slack. ... I had to go and double check just in case I'd imagined the whole thing or the colleague who told was making it up, but I was OK:
https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=23305 (https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=23305)
I understand that screw terminals themselves are not preferred and sprung terminals are to be recommended. I don't know if it was an installation fault or just age but I noticed the immersion heater switch started showing a brown patch which got bigger over time. When got round to investigating a wire was loose and it was quite black inside.
I found these on the RS components website.
https://uk.rs-online.com/web/p/splice-connectors/1787179/
They look as though they cover a better cable range ( somewhat smaller than the others) so I've ordered some to try. Postage is a bit more expensive, but the unit cost is better!
Quote from: GraemeD on January 16, 2021, 21:12
Yes, when wires are twisted together before putting into a screw terminal they will retain some 'springiness' but when 'tinned' and soldered together into a mass then over time the solder will 'smoosh' (if there is such a word) and the contact will become slack. ... I had to go and double check just in case I'd imagined the whole thing or the colleague who told was making it up, but I was OK:
https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=23305 (https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=23305)
Looking at the forum you quote it's clearly quite a complex issue, and there seems to be some debate as to whether heating is involved in the process or not.
I'm guessing that most model railway joins are unlikely to be problematical in real life (apart from just coming adrift), but clearly it's a very different matter when you're wiring an aircraft!
David.
The other point when soldering multi strand wires is that these wires as made are quite flexible but the soldered part becomes a solid metal block and if the transition is flexed by the wire moving then the wire will likely break at the point where the stiff soldered part changes to the more flexible unsoldered part.
So again if you use screw terminals either do not solder the wire or just solder the tip and then the screw will hold on to the more flexible unsoldered part and the wire will be less likely to break.
If you are soldering the wire directly onto another wire or contact then support the wire where it is still flexible eg by heat shrink sleeving or by fastening it to a nearby structure to stop it flexing.
Solid core wires are much less likely to break like this.
Frank
I can vouch for wires breaking where the soldered end transitions into the individual copper strands. I'm not keen on using solid single core wires unless they are fixed in position as again the bend point work hardens and fractures.
It is not for everyone, but for larger or club layouts with a lot of wiring a crimping tool and bootlace ferrules might be worth considering. If you find yourself scrabbling around under a baseboard trying to poke wires into screw terminals while trying to avoid 'whiskers' and splayed ends more times than you care for it can save a lot of frustration. The crimping tool is a bit of outlay though.
There are inexpensive plain ferrules:
(https://i.ebayimg.com/images/g/HpsAAOSwvD5aL5O2/s-l64.jpg)
https://www.ebay.co.uk/itm/100pcs-Uninsulated-Bootlace-Cord-End-Ferrule-Terminals-Crimps-Cable-0-5mm-6mm/162799742287?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D20160908110712%26meid%3D1b668ea733464bbfb832e50b940e2f58%26pid%3D100677%26rk%3D3%26rkt%3D30%26mehot%3Dnone%26sd%3D223433835482%26itm%3D162799742287%26pmt%3D1%26noa%3D0%26pg%3D2386202%26algv%3DSimplAMLv5PairwiseWeb&_trksid=p2386202.c100677.m4598 (https://www.ebay.co.uk/itm/100pcs-Uninsulated-Bootlace-Cord-End-Ferrule-Terminals-Crimps-Cable-0-5mm-6mm/162799742287?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D20160908110712%26meid%3D1b668ea733464bbfb832e50b940e2f58%26pid%3D100677%26rk%3D3%26rkt%3D30%26mehot%3Dnone%26sd%3D223433835482%26itm%3D162799742287%26pmt%3D1%26noa%3D0%26pg%3D2386202%26algv%3DSimplAMLv5PairwiseWeb&_trksid=p2386202.c100677.m4598)
and fancier ones with shrouds that also make inserting wires into awkward holes easier:
https://www.amazon.co.uk/Estmoon-Self-Adjustable-Crimping-Terminals-0-08-10mm%C2%B2/dp/B07YFV5S1J/ref=asc_df_B07YFV5S1J/?tag=googshopuk-21&linkCode=df0&hvadid=389357479641&hvpos=&hvnetw=g&hvrand=3583976217872069029&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007293&hvtargid=pla-829327209833&psc=1&tag=&ref=&adgrpid=80316621555&hvpone=&hvptwo=&hvadid=389357479641&hvpos=&hvnetw=g&hvrand=3583976217872069029&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007293&hvtargid=pla-829327209833 (https://www.amazon.co.uk/Estmoon-Self-Adjustable-Crimping-Terminals-0-08-10mm%C2%B2/dp/B07YFV5S1J/ref=asc_df_B07YFV5S1J/?tag=googshopuk-21&linkCode=df0&hvadid=389357479641&hvpos=&hvnetw=g&hvrand=3583976217872069029&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007293&hvtargid=pla-829327209833&psc=1&tag=&ref=&adgrpid=80316621555&hvpone=&hvptwo=&hvadid=389357479641&hvpos=&hvnetw=g&hvrand=3583976217872069029&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007293&hvtargid=pla-829327209833)
Graham
I used to use a lot of the more expensive shrouded ferrules when I was working so I actually have a pukka crimp tool for those. Might go back to them for some things. Thanks for reminding me.