Is it fine to solder ferrules to wire?

MontyYoungMontyYoung Registered Users Posts: 3
edited December 2018 in Solar Beginners Corner #1
I have read how soldering the actual copper strands is a bad idea for screw terminals as the solder creeps & the screw loosens over time.

But I have been trying ferrulle crimps to 10 & 6AWG wire &  after crimping with the proper crimper the ferrule can be pulled off the copper quite easy with just a pair of pliers. Is this kind of soft crimp really safe? So i held the soldering iron to the ferrule and feed solder into the end opening. 

This gives a strong bond and to my understanding seals against oxidation between copper and ferrule.

So is this a good practice regards to creeping? Or is standard ferrule crimping good enough?



  • BB.BB. Super Moderators, Administrators Posts: 28,441 admin
    It sounds like either the ferrules and/or the crimping tool is the wrong size for the cable being crimped. You should not be able to pull the crimped items apart.

    The idea of using solder to make electrical connections for cabling has always been a little bit controversial.

    There are many who like to use solder to make electrical connections. As long as you use rosin core solder (or other non-corrosive flux) and support the finished joint (do not allow flexing of the wire/joint), it does make for good electrical connections.

    The other side of the argument... When solder is used, it wicks up the strands of wire and where it stops, it makes a fulcrum that focuses bending forces right at the joint, and makes the copper work harden and fail much easier than a properly crimped connection. Also, using solder for mechanical connections is bad because if the connection overheats, the solder melts and the joint pulls apart--And can create a short circuit/arc/fire/etc... So standard wiring connections in most industries only allow/support crimped connections.

    But finding the correct size crimp connectors and crimping tools can be a real pain.

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  • mcgivormcgivor Solar Expert Posts: 2,566 ✭✭✭✭✭
    edited December 2018 #3
    There are differing schools of thought regarding tinning of fine stranded conductors, in some circumstances it is a requirement such as fire alarm applications but for reasons of supervision where one strand may satisfy supervision but not able to carry load . Crimping with commnly available tools is as you have discovered is not that reliable. Personally I solder all stranded conductors but the technique is important, the application of too much heat can soften the transition point, where the solder ends. First tin the connector, then the conductor by applying heat to the tip, once both are lightly tinned insert the conductor and apply heat to the connector, the part with the highest heat requirement and feed in a little solder. Practice on a few to aquire the technique, it should take very little time to fuse the two together, seconds in fact once both are tinned. So far I've never had a failure of a soldered connection, other than when I was an apprentice. Just my opinion others may differ. 
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  • jonrjonr Solar Expert Posts: 1,195 ✭✭✭✭
    You need a better crimper, matched to the ferrules.   Pulling on it is good verification.

    I've seen all the above mentioned problems with solder.  So while it intuitively seems like a good thing, it isn't.
  • mike95490mike95490 Solar Expert Posts: 8,118 ✭✭✭✭✭
    But I have been trying ferrulle crimps to 10 & 6AWG wire &  after crimping with the proper crimper the ferrule can be pulled off the copper quite easy with just a pair of pliers. 
    You are for sure, not using a "power distribution grade" hydraulic crimper.   There may be some 36" hand crimpers for 10ga, but #6 is 12 ton hydraulic.

    A proper power distribution grade crimp cold flow welds the wire to the crimp. it does not pull out, the wire will break first, with a proper crimp.
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  • stmoloudstmoloud Registered Users Posts: 86 ✭✭
    edited December 2018 #6
    A while back I watched a US utuber pool solder into a battery lug and then plunge a cable into it. I thought, that's a good idea. But for neither love or money I could not find any such lugs here in NZ. And the price for ready made 200 Amp cable was ridiculously expensive. The way around this was to take a trip to a welding supplies shop. I bought a metre of Lincoln Electric Maxiflex and had them make up two lug to lug half metre cables They charged only for the parts, labour was free. All for a total of one quarter of what others were charging. Very nice crimping job done with a hydraulic crimper and all lugs heat-shrinked at the cable ends. 

    For smaller wire I use  a cheap crimper that crimps the typical colour coded terminations found in auto shops. The crimpers are only good for one year of heavy use, as they will wear out at the fulcrum point.  With these you must make sure to get the maximum of wire into the terminals. If there isn't enough, you should double or fold over the wire to make sure there is enough to crimp down on. Unless you have the muscle power of a gorilla, you should not be able to fully close the crimpers.  I will then use a 'polygrip' plier to force the crimper to complete the close.

    If done right, these will never pull out with pliers. 

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  • NANOcontrolNANOcontrol Registered Users Posts: 98 ✭✭
    It may not be the best connection, but solder will always be a solid connection.  Generally, if the connection can face corrosion many solder.
  • jonrjonr Solar Expert Posts: 1,195 ✭✭✭✭
    edited December 2018 #8
    > solder will always be a solid connection

    Unless it heats up too much or causes the wire to break or compresses/creeps and causes a loose connection.

    If for some odd reason you really want to use solder, then do a proper crimp first and make sure it doesn't vibrate or get flexed.
  • stmoloudstmoloud Registered Users Posts: 86 ✭✭
    I've soldered all my connections from my panels  though I don't have extreme heat at this location. Probably something I wouldn't do in some parts of the US.
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  • BB.BB. Super Moderators, Administrators Posts: 28,441 admin
    The heat causing solder to melt will not be from "ambient" (room/roof/etc.) temperatures, it will be from some sort of fault condition (overcurrent, corroded connection getting hot, vibration/movement of cable causing copper wire to work harden where the copper stops wicking up the strands and focuses bending forces at the "fulcrum point").

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