Connect stranded to solid wire

11 years ago

18g stranded wire to 18g solid, attaching power cord to a light fixture - can I just twist the stranded counterclockwise, hold the two wires next to each other, and screw on the standard garden variety wire nuts as usual?

I ask because I actually read the box for the first time in decades (if ever) and it says the wire nuts can only be used with stranded wire that has fewer than 20 strands. Sure enough, the power cord I'm working with uses something like 25 or 26 strands per wire for each of the white, black, and ground.

I've always just used the garden variety wire nuts for this sort of thing in the past. Never a meltdown or fire.

I'm thinking that statement on the box is assuming you're doing wall wiring that'll draw at or near the amperage the wire is rated for. As opposed to just wiring up a low-amp device like a light that will be running at like 8% of the wire capacity, max.

Am I good to go with the garden variety wire nuts, or have I Been Doin' It Wrong for umpty-bazillion years?

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Comments (5)

kudzu9
11 years ago
The more strands, the thinner the individual wires, which increases the likelihood of individual strands breaking from the twisting of a wire nut when you are joining stranded to solid.

However, I have to ask: What kind of fixture is this? It's not customary for there to be solids in a light fixture. Are you sure they are solid, or are the ends simply tinned with solder and look solid? I'm presuming this splice will be protected, like inside the ballast space of a fluorescent fixture? If not, I would be concerned about the longterm safety and the appropriateness of this kind of splice. Please provide more detail as I would hate to see you take a UL-listed fixture and make it unsafe.

Having said all that, if this is a situation where you are really joining stranded to solid and the splice will be in a safe location, then you could improve the splice by tinning the stranded ends, and then use the wire nuts. Or twist the strands around the solids by hand, solder each pair, and then screw on wire nuts for protection.
kudzu9
11 years ago
zensojourner-
So...what's the story?
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mtvhike
11 years ago
I'm not sure I understand the situation. As I read it, there is a wall or ceiling fixture. The wires for the fixture are stranded, and the feed wires are solid. I'm surprised that they are 18 ga, not 14 ga, but I would guess that if they were 14 ga, this would be completely normal, and wire nuts for connecting the fixture wires to the feeds would be OK. Am I right?
kudzu9
11 years ago
MTVhike-
Yes, the original posting is a little vague, but the OP is referring to power "cord" rather than cable, and it's 18 ga, so that couldn't be a power feed (as in Romex-type wiring).
Pyewacket
Original Author
11 years ago
Sorry, I've been down again with whatever this thing is that won't go away. Started as a cold. Apparently humans are not immortal, but some of our diseases appear to approach it, LOL!

It's a fluorescent fixture. I guess I'm not sure what wasn't clear in the OP, except that I didn't list the amperage - which is 800mA max and something around 600mA at normal operating levels.

Actually need to work on several. I have some that need cord replacements and some that came direct wire that I'm converting. I will also be doing some ballast replacements eventually, and I'll most likely replace old power cords at the same time.

In the meantime I've identified the proper connectors for this use. They are Wago 222 series lever nuts, and they will handle solid, stranded, and the fine-stranded wire in the sizes with which I am working. These are UL etc approved for many many applications, including in-wall supply lines.

These fine stranded conductors in power cords are something new to me, so I guess I've NOT been Doin' it Wrong in the past when I used wire nuts. I've also located much cheaper power cord for future use, which is 16g NEMA 15/5 to ROJ wire for hospital use. The stuff in the lengths I need seems to be available for $1 or less each. Way WAY overkill for my use.

BTW: I recounted the # of wires in the conductor while wearing my Opti-Visor. There are 41 wires, not 26, which makes that Class M fine strand. Even with my glasses on that's all the better I can see without extra magnification. I miss my eyesight! LOL!

This post was edited by zensojourner on Sun, Dec 14, 14 at 22:36