Connecting stranded wire to screw terminals

[Stephen Tashiro]

What's the secret to getting a neat looking connection when attaching stranded wire to screw terminals?

I find that connecting stranded wire to screw terminals (like those on a lamp socket shown at http://www.lamppartsrepair.com/p/common-repair-tips.html) tends to flatten the bare wire and leave hairs of it sticking out. Should I twist the wire tightly and tin the end of it with solder? The wires shown on that webpage appear to have a tinned ends.

[John McClanahan]

I bend the U or loop and solder the wires.

John

[George Bokros]

Install ring terminals on the wire first.

[Pat Barry]

Strip a bit more than you would normally do, twist tightly, bend into hook around screw and pinch tightly around screw with needle nose before torquing the screw.

[Jim Koepke]

I sometimes tin the wire first. Usually do as Pat suggest. One trick is to leave the insulation on past the stripped section. This leaves a neat appearance after the excess is cut off with a good pair of dykes.

Remember to wrap the wire around the screw clockwise.

jtk

[Mike Null]

I prefer ring terminals or solder.

[Dave Zellers]

Remember to wrap the wire around the screw clockwise.

jtk
Very important. Also just as important to twist the strands clockwise before that.

[Shawn Pixley]

Twist and tin them with solder. Wrap clockwise so it tightens with the screw.

[John K Jordan]

...Should I twist the wire tightly and tin the end of it with solder? The wires shown on that webpage appear to have a tinned ends.

I usually twist tightly and tin part of the end with solder or use a crimped connector.

Crimping connector on the wire is recommended where the wire is subject to flexing since fine stranded wire will eventually break at the point where the stranded meets the solder. This can be avoided by going easy on the solder and not allowing it to extend out past the head of the screw. Or, simply constrain the wire movement.

Crimping avoids the issue. I like the slotted crimp connectors (can't remember the name) that slip under the screw head instead of the ring connectors for those devices where the screw is made to not be easily removable (so it can't be lost).

JKJ

[Leo Graywacz]

I usually do this with an auto stripper. The stripper will remove 1/2" of insulation. So instead of starting at 1/2" in from the end of the wire you start in at 1". When you use the stripper it will strip the insulation for 1/2" and leave 1/2" of wire with insulation at the end of the wire. You clip the empty 1/2" of insulation off. This will keep the wire from fraying out when you apply screw pressure to it. Just make a "U" loop with the wire and slip it onto the terminal and tighten it. Leave the insulation on the end of the wire.

[Kev Williams]

if you tighten screws like I do, NOTHING will keep the strands from fraying out :)

But if I'm being picky, I'll cut lots of insulation off, twist tight, and once around the screw I'll cinch it up and hold it tight with needlenose pliers while tightening the screw, then cut off the excess wire with dikes.

But usually I'm not so picky... ;)

[John Terefenko]

Very important. Also just as important to twist the strands clockwise before that.


This statement is wrong. Twist the wires counter clockwise and then bend around the screw clockwise and tighten. electrician for 43 years.

[Malcolm Schweizer]

+1 for ring terminals.

[Bob Grier]

Copper wire used in the marine industry is always stranded and tinned. Each strand is tinned, not after the strands are assembled into a wire. I was once told by a electronics person working on my boat to not solder the ends of the wires and then crimp them into a ring connector or secure in any other connector. The reason is that if the connection were to either loosen up from vibration or stress releave due to the solder softening from the circuit heating up, and then it cools down, arcing could start taking place making for more heating and loosening. Not good situation.

The best way, according to him, is to use crimp connection if using a connector (ring, spade or whatever) and then solder the wire at the crimp after crimping to give protection against corrosion and also I suppose it gives some security to the crimped part of the connection although I don't think that is necessary if properly done.

[Rick Moyer]

This statement is wrong. Twist the wires counter clockwise and then bend around the screw clockwise and tighten. electrician for 43 years.
Interesting. Could you explain why this is better than clockwise? It would seem to me that as one turns the screw, a clockwise twist of the wires would be compressed whereas a counterclockwise twist would want to unravel? I'm just a homeowner so likely there's something I don't understand.

[John Terefenko]

Interesting. Could you explain why this is better than clockwise? It would seem to me that as one turns the screw, a clockwise twist of the wires would be compressed whereas a counterclockwise twist would want to unravel? I'm just a homeowner so likely there's something I don't understand.

It is actually the opposite. when you twist clockwise and then put under screw, the screw will splay the wires out thus the stray hanger. When you twist counter clockwise and put under screw the screw will not untwist the wires thus they stay together. Try it someday and watch the action of the wires as you do both. Of course the best method here is to use Stakons. Clean and fail proof. No chance of stray wires unless you miss one putting in the stakon.

[Kev Williams]

makes sense- think spiral cut gears, the clockwise rotating screw wants to turn the wire beneath it counterclockwise :)

[Stephen Tashiro]

In wiring a lamp socket, is it useful to use crimp-on connectors on the ends of the wires? That would be easier than tinning the ends of the wires.

I don't understand how the shape of typical lamp sockets is supposed to accommodate the wires. There is a ridge around the bottom bottom of the socket below the screw terminal so the wire can't sit flush with the surface below the screw terminal.

[Jim Koepke]

In wiring a lamp socket, is it useful to use crimp-on connectors on the ends of the wires? That would be easier than tinning the ends of the wires.

I don't understand how the shape of typical lamp sockets is supposed to accommodate the wires. There is a ridge around the bottom bottom of the socket below the screw terminal so the wire can't sit flush with the surface below the screw terminal.

Many lamp sockets do not have the room for a crimp-on connector inside the assembly.

Desk and floor lamps have been wired for over a century with stranded wire without major problems. Well, maybe without problems by many folks.

My lamp socket wiring usually doesn't include tinning the wires. My greenhouse was wired with stranded wire. There are four switches, a dozen outlets and five lamp sockets all done with stranded wire under screw heads and wire nut connections.

It isn't rocket science.

Make it neat and do not over tighten the screws. Also remember to not wrap a wire around a screw terminal with the wire crossing over itself.

To me it seems simple, after all my father had me doing such at about age 8 or so.

jtk

[Ken Fitzgerald]

Twist and tin them with solder. Wrap clockwise so it tightens with the screw.

I once had to take a week long US Navy micro-miniature repair class. The final test was 4 hours to solder 70 connections to NASA standards. The standards were even more rigid as too much solder isn't good either. In the mid-70s, NASA standards required that any strand not touching the element to which it was being soldered had to be coated with solder but still distinguishable as an individual strand.

I agree with you, Shawn. Twist clockwise and solder. Then twist the tinned wire clockwise around screw and tighten. Electronics 40+ years

[Myk Rian]

I twist the wires in the same direction they are twisted when made.

[Ronald Blue]

This is a simple and effective solution. We use these on machinery that's subject to a lot of vibration and they hold up well. They are thin and crush under the screw but contain the wire strands quite well.

fastenal.com/products/details/0749664?r=~|categoryl1:%22601280%20Electrical%22|~ %20~|categoryl2:%22601347%20Terminals%20and%20Wire %20Connectors%22|~%20~|categoryl3:%22604304%20Ferr ules%22|~%20~|sattr01:^%2212%20AWG%22$|~

[Malcolm Schweizer]

Copper wire used in the marine industry is always stranded and tinned. Each strand is tinned, not after the strands are assembled into a wire. I was once told by a electronics person working on my boat to not solder the ends of the wires and then crimp them into a ring connector or secure in any other connector. The reason is that if the connection were to either loosen up from vibration or stress releave due to the solder softening from the circuit heating up, and then it cools down, arcing could start taking place making for more heating and loosening. Not good situation.

The best way, according to him, is to use crimp connection if using a connector (ring, spade or whatever) and then solder the wire at the crimp after crimping to give protection against corrosion and also I suppose it gives some security to the crimped part of the connection although I don't think that is necessary if properly done.

Good advice. They use stranded wire because stuff on boats moves- even the hull can flex. Stranded wire flexes without cracking. I use heat shrink terminals or add heat shrink over the terminal separately. This not only protects the exposed wires from corrosion, but it also keeps the wire from getting stressed at the join to the terminal.

[Alan Bienlein]

This statement is wrong. Twist the wires counter clockwise and then bend around the screw clockwise and tighten. electrician for 43 years.

This is how you do it. No need for any thing else such as soldering or crimping on connectors. I was taught this by an electrician I was working for.

[John K Jordan]

All this varied advice points to different ways to achieve the same thing with stranded wire - a connection with good conductivity, strength to not come apart, and a clean connection with no stray strands to cause shorts. Many of us have been making these connections successfully for decades with obviously different techniques.

I found this tutorial on making electrical connections with wires. It looks reasonably good, especially concerning the details of crimping stranded wires.
https://learn.sparkfun.com/tutorials/working-with-wire

This doc from Molex is full of useful information including charts at the end, for those who like to read:
www.mouser.com/ds/2/276/molex-487566.pdf

BTW, my own preference for crimped connections for most stranded wire comes from a military project our group did creating a mobile control and data acquisition monitoring station for field explosives. I wrote all the software and had a hand in the design and implementation. This was in the '80s and the specifications for that project were for crimped connectors on most stranded wire connections. It was explained to us that where wires were subject to movement from either flexing or vibration, soldered stranded wires may break at the point just past where the wire turned solid from the solder. This did not apply to this type of military connector where soldering was required, however the cable connector in this case provided strain relief to keep the wires from moving at the connection:

355301

For standard lamp sockets I have no problem with stripping, twisting tightly, tipping with solder, and tightening the screw firmly. As mentioned in another thread, I'm also a believer of using a dab of dielectric grease on most friction connections, especially those outside or in damp locations (under a trailer, etc.) As with any connection, tug after connecting to be sure it is tight. For connections exposed to the environment, I like to use heat shrink tubing if possible.

Another favorite way to seal connections, is the self-sealing silicon stretch tape, sometimes sold as Rescue Tape:
https://www.amazon.com/Rescue-Tape-RT1000201201USC-RT1000201201USCO/dp/B001JT0ET8
This is especially good for larger connections, such as two extension cords plugged together. The tape bonds to itself and makes a great seal. I like to use the clear tape. It will also make temporary repairs on water hoses.

JKJ

[Brian Elfert]

This statement is wrong. Twist the wires counter clockwise and then bend around the screw clockwise and tighten. electrician for 43 years.

Why counter clockwise? That seems backwards when every stranded wire I recall using is twisted clockwise from the wire manufacturer.

[Alan Bienlein]

Why counter clockwise? That seems backwards when every stranded wire I recall using is twisted clockwise from the wire manufacturer.


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http://www.sawmillcreek.org/images/misc/quote_icon.png Originally Posted by Rick Moyer http://www.sawmillcreek.org/images/buttons/viewpost-right.png (http://www.sawmillcreek.org/showthread.php?p=2664784#post2664784)
Interesting. Could you explain why this is better than clockwise? It would seem to me that as one turns the screw, a clockwise twist of the wires would be compressed whereas a counterclockwise twist would want to unravel? I'm just a homeowner so likely there's something I don't understand.



It is actually the opposite. when you twist clockwise and then put under screw, the screw will splay the wires out thus the stray hanger. When you twist counter clockwise and put under screw the screw will not untwist the wires thus they stay together. Try it someday and watch the action of the wires as you do both. Of course the best method here is to use Stakons. Clean and fail proof. No chance of stray wires unless you miss one putting in the stakon.

[Brian Elfert]

I've never tried it, but I would think the stranded wire would fight being twisted the opposite directed it was twisted at the factory. I deal a fair bit with finely stranded marine wire and I have a heck of a time getting that to stayed twisted in the clockwise position, let alone twisting it completely opposite. I never wrap marine wire around a screw and mostly use crimped terminals with it.

[John Terefenko]

I've never tried it, but I would think the stranded wire would fight being twisted the opposite directed it was twisted at the factory. I deal a fair bit with finely stranded marine wire and I have a heck of a time getting that to stayed twisted in the clockwise position, let alone twisting it completely opposite. I never wrap marine wire around a screw and mostly use crimped terminals with it.


If you crimp then you have no problem. But I suggest you try the counterclockwise twist Just watch the action of the strands and do it both ways. You will never believe me unless you try for yourself. I can not do it for you. Just giving my advice that I have used for many years. I have seen people wrap solid wire around a terminal couterclockwise and now that is wrong.

[Jason Roehl]

Another technique I saw mentioned on SMC (by a retired electrician) is to strip the wire further back, but leave the piece of insulation on the wire. Twist the wire counter-clockwise, then loop the exposed wire clockwise around the screw.

As a clockwise twist of wire strands is compressed, the strands first contacted by the bottom of the screw head will "roll outward" from the screw shaft. If the strands are twisted counter-clockwise, the strands will be forced closer to the screw shaft as they are compressed.