Connecting Stranded Wire; A Better Way

You do not see manufactures solder crimps, because it defeats the purpose of using them in the first place. Speed of manufacturing with uniform connection, but I do not see them using crimps and manual crimping tools commonly used by hobbiests. I have often read of electricians and hobbyist's having problems with poor manual crimps and problems with uniform crimps using the typical inexpensive crimping tools. Wires can also be damaged from using too much force on a crimp. I have often seen crimps come loose and corrode (increased electrical resistance) over time. The vibration stresses to break wire over time in the hobby environment would be far less likely, than a non-manufacturer crimped wire coming loose. With high voltage wires, as mentioned, crimp, solder at the tip, and for added protection use fusable shrink tubing. They sell crimps (3M) that include a fusable insulator. Improper securing of wires is also a factor in breakage from vibration.
 
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You do not see manufactures solder crimps, because it defeats the purpose of using them in the first place. Speed of manufacturing with uniform connection, but I do not see them using crimps and manual crimping tools commonly used by hobbiests. I have often read of electricians and hobbyist's having problems with poor manual crimps and problems with uniform crimps using the typical inexpensive crimping tools. Wires can also be damaged from using too much force on a crimp. I have often seen crimps come loose and corrode (increased electrical resistance) over time. The vibration stresses to break wire over time in the hobby environment would be far less likely, than a non-manufacturer crimped wire coming loose. With high voltage wires, as mentioned, crimp, solder at the tip, and for added protection use fusable shrink tubing. They sell crimps (3M) that include a fusable insulator. Improper securing of wires is also a factor in breakage from vibration.

Thank you. I would walk past this man doing the wiring from a blue print. Its been over 40 years ago. A lot of changes and improvements since then. Appreciate your insight.
 
Manufacturers of compression-type terminal blocks and connectors recommend against tinning any stranded wire that comes under direct compression, for the reason that over time the solder can deform and cause a loose connection.

If you use a ferrule, this deformation should not take place, so it will do no harm to solder the wire in the ferrule, but I believe it is unnecessary, as crimped connections have been shown to be the most reliable,

I agree with using ferrules and using an appropriate crimping tool as well. NFPA79 2012 which affects all machine tool and special machinery wiring states that stranded wires shall not be tinned or soldered unless the connection is specifically designed for soldering. An example of allowing solder is a connection to a pot or solder terminal. I prefer to abide by NFPA79 since I occasionally build special machines for local businesses.
 
NFPA79 guidance has to do with connections to devices, I did not see any specifics to the crimp terminal itself, and is somewhat specific to the type of connection/terminals. The same applies to the NFPA70 National Electrical Code, which in most terminations at terminals are specific to use of bare wire.
13.1.1.5 Soldered connections shall only be permitted where terminals are provided that are identified for soldering.
13.1.1.8 Means of retaining conductor strands shall be provided when terminating conductors at devices or terminals that are not equipped with this facility. Solder shall not be used for that purpose.
13.5.9.4 Soldered or insulation-piercing–type connectors (lugs) shall not be used. (for motor connections)

They are somewhat different issues. A soldered sire, which is then crimped or just soldered and attached to a terminal, does not allow the wires to move and fill the area, i.e. a single point of contact. This is somewhat like a cold joint, and the solder will also cold flow making the connection come loose with time. There is also the added issue, that people tend to over tighten connection terminals, often breaking or damaging the wire. One reason why most terminals have specific torque specifications, and are specific to acceptable terminations to be used.

Good crimping/connections is all about minimizing the void volume, thus most professional crimping devices provide circumferential crimping. Even with this, in some circumstances it is preferable to solder the "compressed" joint to eliminate any void are and prevent future corrosion.
Crimps.jpg
Having worked in the boat building environment many decades ago, this was usual and common practice for smaller wires. Example below.
http://www.uscg.mil/hq/cg4/cg432/docs/techsheets/2010-02.pdf
"Lugs are available in tinned copper which avoids the corrosion issue at the crimp and under the screw terminal and battery lug. Lugs can be purchased insulated or non-insulated. Insulated lugs are generally used if they are crimped in the field. Non-insulated lugs are used if heat shrink tubing is applied over the termination after the lug is crimped and/or soldered. When soldering, slide a piece of heat shrink up the insulated conductor, apply a liquid or paste rosin flux to the wire, insert into the lug, apply heat to the barrel of the lug and insert solder into the end of the barrel until it is drawn into the strands. Do not use too much solder as it will wick up the wire past the lug and cause the wire to lose flexibility. Slide the heat shrink over the barrel after it cools and use a heat gun to shrink the tubing in place, sealing the insulation and lug to prevent moisture from wicking up the conductor."

If you want additional bedtime reading, this is how NASA does it. http://www.hq.nasa.gov/office/codeq/doctree/87394.pdf
Ferule with solder is one form of connections for termination.

My main concern is that standard crimping tools sold do a very poor job of making a safe connection, just try it and then try to pull on the wire and see if it moves or pulls out. I always do this after crimping, and you would be surprised how often the wire pulls out. Proper soldering at the tip fills the voids, and minimizes the risk of pullout/corrosion. That along with heat shrink tubing, especially the fusible kind make for a very stable connection.

To address the topic of this post, ferrules, however you want to use them are great.
 
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That picture looks familiar......oh, that's right! It was in that WhitePaper I linked to.
 
I have never had a problem with good quality crimp on insulated terminals when using a ratcheting crimper. Those combined crimper / wire strippers are fine for an emergency tool in the tool box behind the seat of the truck but for serious work a decent quality ratcheting crimper is the right thing to use. good_crimper.jpeg bad_tool.jpg
 
You can also, depending on the size of the strands of the wires, turn the wire ends counterclockwise and then wrap to the right.
When the screw tightens it pulls the individual twists toward the direction of the screw and the wires don't spread out.

If you have enough screw you can add an under the screw clamp. It looks like a flat square washer with grooves in it.
 
I'll second the Weidmuller tools.
I have half a dozen of them that I use at work and their quality can't be beat.
I have two of their Ferral crimpers. The PZ-6 Roto and the PZ-6/5
 
I think MKSJ (maybe others) said, and I agree: don't solder the wires before you wrap, crimp, clamp, or screw them down. The solder is relatively soft and can yield and deform, loosening the connection. Soldering after has a pretty small chance of causing a problem, and does prevent corrosion between the wire and terminal. Everyone knows to use rosin core solder, not acid core from the roofer's world, right?
 
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