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Electricians- school me on fine strand/DLO cable

6K views 4 replies 4 participants last post by  bikebumIII 
#1 ·
I stumbled across this article by accident the other day on fire hazards with improper terminals/lugs and fine stranded cable.

I don't do house wiring, but I do occasinally work with fine stranded cable so I thought it was interesting reading.

I was always under the impression that fine stranded cable could carry more current than equivalent gauge Class B cable. That and it's more flexible, and I can buy it by the foot at any welding supply so I tend to use it more often.

If I'm doing things wrong - please tell me a better way:

On welder connections with set screws I wrap the end of the cable in a strip of soft copper sheet and use the little steel spreader tab that come supplied with the connectors. I'm not too worried about this - seems good and strong, well connected. It also goes 100% with the manufacturer's directions. (I do notice that if you flip the direction of curvature on the spreader tab it holds better on smaller gauges)

But on crimp-on lugs I'm a little worried now. I didn't know there was two types. I do use the long ferrule crimp on lugs with a rounded off chisel to crimp them (I can't justify the expense of a commercial "bolt-cutter style" crimper and haven't been able to find a little "hammer type" one locally). I then fill the lug with solder and add a heat shrink sleeve. Is this a bad practice? Any suggestions are appreciated.

I don't have to do anything that meets a code requirement, but this is the part that has me questioning the integrity of my crimps:

Factory-supplied markings and literature indicate
which lugs are suitable. An example is the ILSCO FE
series of lugs in sizes 2/0 AWG and larger (see photo
6). Burndy makes the YA-FX series of lugs in sizes 8
AWG and larger that have been listed for use with fi ne
stranded cables. In both cases the lugs are solid copper.
It should be emphasized: Most crimp-on lugs are not
listed for use with fine-stranded wire. Where the crimpon
compression lugs can be used, they must be installed
using the tools recommended by the manufacturer and,
of course, they must be attached to a stud with a nut
and washer.
It is suggested that the use of fine-stranded conductors
be avoided wherever possible. Where such cables
must be used, they should only be terminated with the
appropriate connectors/lugs. Previously installed systems
should be revisited and the cables replaced where
possible or terminated properly.
Thoughts/Notes:
I assume with AC changing polarity 60 times a second any arcing would be more quickly destructive than on something like a battery cable, but I figure high current is still high current no matter what it's wired to or what direction it's going. There's a diesel place nearby that I can have crimp my large lugs (2/0), but ocassionally I have to make a jumper or power lead for something that involves smaller cable. The guy at one of my welding supply stores said "Hmmm, I dunno - I just use a big vise" when I asked about 4 gauge crimping tools, so I'm not really impressed with his knowledge. I already know that driving a set screw directly into fine stranded cable will tear the sh!t out of it. Should I switch to using the class B stuff for my small projects or is there something I'm missing? I think Home Cheapot sells normal Class B cable down to about #4 or #6 by the foot.

Thanks - Matt
 
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#2 ·
Squeeze it till the copper juice comes out.

Have you tried looking at those blocks that have reliefs casted into them specifically for terminating end lugs?

I know it seems butch, but sometimes I have cut a section of thick steel tube in half (bisect it--you can see the inside...a split) and use thick flat stock NOT A SCREWDRIVER to terminate a lug end. The tube or pipe must be thick and form-fit around the circumference of the lug, so as to cradle it.

I did this when I replaced all my welders ground clamps and then soldered the lugs for extra protection.
 
#3 ·
I'm not a fan of soldered connections. Normally you create a cold joint, or you melt back the cable insulation as the solder wicks into the cable, and stiffens the end of your ultra-flexible cable.

Crimping with an anti-oxidant compound makes most sense to me.

You can make your own crimper out of a boltcutters too:


(FYI, the electric vehicle community is a good resource for high-current cabling and connections).
 
#5 · (Edited)
I am a commercial electrician and you can buy all kinds of lugs from the supply house. We set screws all the time into the stranded stuff. Especially on so cords. they handle a lot of power if you are running a contractors trailer and so on. You can always get solid cable. It is a pain to bend around though. We order larger stranded cable sometimes for special stuff, just because you cannot always count on the 100 million trillion copper wires to make contact, like you could count on the solid wire. Although then you can get into scaring your wire especially your solid and lose some connection that way. I think what you are doing is fine. Persoanlly I would not even put the copper sheet around the wire, I would just set the set screw and use it. You can always jump up another wire size if you are worried....just my 2 cents...hope this helps you out a little....Oh yeah and as far as the crimpers go you can try getting the klein hand crimpers around your wire $20-$30. We use racheting ones for big stuff, same for cutting unless you use the sawzall...
 
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