How to connect #12 stranded to #10 solid

[Duane Bozarth]

xrongor wrote: ...

No, there is no solder joint at all in that case...

[HorneTD]

The only places the US NEC forbids the use of solder is in connecting grounding or bonding conductors to electrodes and connecting Equipment Grounding Conductors to boxes. In both cases the connection may not be "depending on solder."

250.70 Methods of Grounding and Bonding Conductor Connection to Electrodes. 250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes.

In other applications the US NEC specifically permits soldering vis.

[110.14 Electrical Connections. Because of different characteristics of dissimilar metals, devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be properly installed and used. Conductors of dissimilar metals shall not be intermixed in a terminal or splicing connector where physical contact occurs between dissimilar conductors (such as copper and aluminum, copper and copper-clad aluminum, or aluminum and copper-clad aluminum), unless the device is identified for the purpose and conditions of use. Materials such as solder, fluxes, inhibitors, and compounds, where employed, shall be suitable for the use and shall be of a type that will not adversely affect the conductors, installation, or equipment.

(B) Splices. Conductors shall be spliced or joined with splicing devices identified for the use or by brazing, welding, or soldering with a fusible metal or alloy. Soldered splices shall first be spliced or joined so as to be mechanically and electrically secure without solder and then be soldered. All splices and joints and the free ends of conductors shall be covered with an insulation equivalent to that of the conductors or with an insulating device identified for the purpose.] copyright 2002 the National Fire Protection Association.

-- Tom H

[toller]

I tried soldering on some scraps. I dipped the wires into flux and then tried to solder them. The solder adhered to the stranded wire as well as could be, but it skated right off the solid.

I have never soldered anything but stranded before, but don't understand why the solid is different.

Any advice here?

[Greg]

More heat. If you have the wire hot enough, without oxidizing the copper, the solder will stick (actually form an alloy). Soldering is a trick that was well known to old electricians but was lost whwn they started using wirenuts. BTW an electrician's soldering iron is ~200w, about an inch in diameter with a 5/8" or larger tip. The idea is that the tip brings enough heat to the job that it instantly brings the ends of 2 or 3 #12s to soldering temperature without slowly heating the length of the wire and melting the insulation. If it takes more than a second or two, you need a bigger iron.

[Doug Miller]

[snip]

See that ? "Mechanically and electrically secure without solder." That means that the connection may not depend on the solder.

[Doug Miller]

You probably need a hotter soldering iron. I bet you've got a fairly low-powered unit. Try something around 100W or bigger.

Also, don't use plumbing solder, which is lead-free. Get some 50/50 or 60/40 leaded solder and try that.

[newsgroups01REMOVEME]

I think you're right, the tinning process isn't making the connection, just organizing the wires. But then you might be in violation of 2002 NEC 110.3b ( label and listings) since wire nuts say nothing about tinned wires, just usually copper, copper-clad AL, and AL depending on the manufacturer.

Still an interesting question.

later,

tom @

[newsgroups01REMOVEME]

I think this points out that you must NOT rely on the solder. You must first do the job first then add the solder second.

Which leads me to the question, after you mechanically and electrically secured your connection, why would you add solder? Where is this a good practice?

Thank you,

Tom @

[Chris Lewis]

According to Doug Miller :

If you use plumbing flux, _clean_ the result very thoroughly. Acid flux eats copper. Much more critical with electronics (small wires etc) and usually not a factor with plumbing (big copper ;-), it still can matter with house wiring.

[toller]

I called every electrical supply house in town. They will order me a box of

100, but don't carry it. Some will also order me the Ideal equivalent, but don't stock them either. You wouldn't have 4 you could toss in an envelop would you? I would be most grateful. The alternative seems to be soldering them, and I am not having any better luck with that; my soldering iron is not big enough.

Home Depot carries the split bolts, but insulating them would be a problem.

[toller]

Just occured to me that if you are kind enough to oblige me, you won't get far with the fake email address. I am at [e-mail]. Remove the spam of course. Thanks.

[Greg]

I am still not sure why you are having so much trouble with a wirenut. If you have a red one. wrap the stranded around the solid with a bit of the stranded beyond the solid and twist on the nut I don't know how you would pull them apart without breaking the wire.

[newsgroups01REMOVEME]

Heat shrink tubing not fit?

later,

tom @

[Roger Shoaf]

First off you can attach a stranded wire to a solid wire inside a wire nut just fine. If the wire nut is sized for 2 or 3 connectors I will usually wrap the stranded around the solid from top to bottom and then kind of flip the end over the top before twisting on the wire nut.

To test take a scrap of each assemble and see how hard you have to pull to obtain a failure. If it is easy then you are using too large of a wire nut or you did some thing wrong.

If you need to pull real hard then the wire nut is doing its job.

I interpret the phrase mechanically and electrically secured to mean you twist the wires together rather than laying them side by side to solder them. It might have a different meaning if you were dealing with some heavy cable or something.

[Greg]

Give that man a cigar, we have a winner. That is what they mean. If you wrap a stranded around a solid a couple times and solder it you will break the wire before the joint fails.

[Roger Shoaf]

The same is true for a properly installed wire nut without the solder also.