Soldering or splicing

Re: Soldering or splicing

Hairfarm wrote: »

Like this: http://chevythunder.com/twist_wires_together.jpg

Or like this: http://imagesdesavions.com/2m/mesh.jpg

My soldering gun can't seem to heat up the wire enough to melt the solder onto it.

Not sure either of those are appropriate. When butt-soldering wires, a "Western Union" splice is best.

http://en.wikipedia.org/wiki/Western_Union_splice

Complete the splice, in the usual manner, then solder and cover with double-walled heat shrink.

Re: Soldering or splicing

inetdog wrote: »

But not really great for stranded conductors or for large gauge wires, both of which are common in PV work.
Of course for really large gauge wires some sort of mechanical connector or a cadweld is better anyway.

Western Union splicing stranded conductors works just fine, and I'm not sure I'd call a #10 (what Cariboocoot mentioned) "large". Practice making Western Union splices helps as well. The key is that Western Union splices are mechanical strong, whereas the other sorts of splices mentioned aren't. Solder, especially high lead solder (like a 60/40) has little or no mechanical strength.

Still -- much better to avoid the need for splicing in the first place.

Re: Soldering or splicing

Cariboocoot wrote: »

Shame they had to ban real (lead) solder, as it had a broader operating temperature. This safe stuff is a bloody nuisance.

Surprise! At least it was for me. I just received some from these guys, along with some 12 volt relays and other stuff. Found service excellent. Ordered online and they delivered. Solder price was a lot better than I had expected.
Minimum Order:$50.00 minimum for merchandise, shipping extra.
http://www.abra-electronics.com/categories/Soldering/
Not sure where it comes from, Quebec I think, but anyway no import duties etc for me.

Re: Soldering or splicing

electrical (rosin core solder) protects the joint from corrosion, but you have to have things clean and hot enough, for the solder to flow on it's own, not just globbing it on like metallic hot melt glue. And Julie is right, solder is weak, so a decent splice/mechanical connection has to be present first. With a couple of #10 wires, you will likely heat the copper so much, it's going to melt the insulation quite a ways down the wire. Not good.
You are likely going to be better off to put in a large enough pull box, and use wire nuts with moisture proof goop, or split bolt splices.

Re: Soldering or splicing

The problem with soldering a splice is not the solder joint strength itself, which is pretty good if done correctly -- the problem, as Bill has stated, it the points where the stiffened soldered wire meets unsoldered wire. Flexion at these points can lead to breaks.

For joining 10 AWG PV wire to 10 AWG THHN, I've used the inexpensive, yellow insulated 10 gauge butt splices which are easily crimped with good crimpimg pliers. Covered with adhesive lined double wallled shrink tubing its makes a fine splice.

Re: Soldering or splicing

Hairfarm wrote: »

Ok. I'll give that a try. Nice cheap solution too! I can still put heat shrink on it too when I'm done for an extra layer of weather proofing for when it gets up to 113 degrees in the summer while it's also raining at the same time (monsoons)

Then definitely use the adhesive lined! Also, non PV wire should probably be in conduit with splices accessible in a J- box.

Re: Soldering or splicing

mtdoc wrote: »

The problem with soldering a splice is not the solder joint strength itself, which is pretty good if done correctly -- the problem, as Bill has stated, it the points where the stiffened soldered wire meets unsoldered wire. Flexion at these points can lead to breaks.

Copper, which is rather ductile, is much stronger than lead. The ultimate tensile strengths differ by a factor of 5, more or less.

Re: Soldering or splicing

waynefromnscanada wrote: »

Very true, but still the mention of flexing where the solder ends in stranded wire is something to consider. At that exact point, there is a sudden and dramatic change in flexibility. The finer the strands, the more dramatic the change. If there will be no ongoing flexing in that area beyond initial installation, all will be fine, but if by chance there is ongoing vibration and flexing at that point, that's when breakage problems eventually crop up.

Yep, it concentrates the metal fatigue. I have seen that a lot in soldered audio cables that get a lot of flexing; the wires always break right at the point where the solder has stopped wicking into the strands.

Re: Soldering or splicing

waynefromnscanada wrote: »

Very true, but still the mention of flexing where the solder ends in stranded wire is something to consider. At that exact point, there is a sudden and dramatic change in flexibility. The finer the strands, the more dramatic the change. If there will be no ongoing flexing in that area beyond initial installation, all will be fine, but if by chance there is ongoing vibration and flexing at that point, that's when breakage problems eventually crop up.

That's true, and irrelevant. Properly done, a Western Union splice is mechanically strong, which means it doesn't need solder, or as much, to stay together. A proper splice is actually a mechanical connection, with the forces in the wire strengthening the connection. You can't "push" on wire -- it just flops out of the way of the forces. Pulling on the wire jams the two ends of the splice into each other. The wires can't just slip past each other because the perpendicular windings in a Western Union splice would have to un-wrap.

I have some 12/2 Romex and #12 THHN lying around. I'll have to see if I can scrape up the spare time, do a few splices, photograph and post. Even #12s are pretty easy to splice -- it just takes patience, a pair of locking pliers (to hold things together initially) and a pair of lineman's pliers (to work the end of the wire).

Re: Soldering or splicing

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I've done better, but I'd also like to do some laundry and eat dinner, rather than spend the night editing photos.

The key is the last three photos where the wrap goes from the usual "twist" to something that should be perpendicular to the wire. The last two show how to finish off the end. When you have that pointy-barb-thing on each end, you need to bend it around the wire so it won't puncture the heat shrink. You can trim it up with a pair of sharp side cutters. If you don't have heat shrink, mastic tape would work. If you don't trust your work, you could solder the inner third and the outer two thirds should protect that from flexing.

That should be a lot stronger than a crimp-on butt splice, even without solder. It's more compact than a Polaris connector and definitely easier than Cadweld (which would have destroyed the insulation). It's small enough that it can probably be fished. If I'd taken more time and laid the wires out carefully enough to get three or four "perpendicular" wraps around the wire, I'd feel comfortable hanging something heavy from the ceiling with it -- without adding solder.

That's a "long splice". For small or stranded wire, the "short splice" might be better. For heavier gauge wire, get bigger tools. You could probably splice 1/0 if you used longer starting lengths and a piece of rigid conduit for a lever and a large pipe wrench to hold the non-working end. For splicing something that size, I'd go with the Polaris connectors or Cadweld, but I'm sure it can be done in a pinch.

Re: Soldering or splicing

waynefromnscanada wrote: »

Awesome looking splices there tallgirl! It's obvious this is not the first time you've done this. lol

That one is a piece of crap.

And you're right -- not the first time. Won't be the last time ...