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I'm working on a raspberry pi project - a sump pit monitor that sends an emergency email if a float switch above the point where the water triggers the pump is switched (purely for monitoring, not driving the pump or anything, mainly peace of mind). I have a couple of float switches I'm using. The float switch wires are 24 awg and about 15 inches. I need them to be a few feet so I'm planning to buy some 24 awg wire and splice them to the switch wires. The wires are AWM 1007 - will any 24 awg wire do? This might be a dumb question but the bare wire is a silverish color. Is it safe to assume it's copper or could it actually be something else? Does it matter?

Anyways, for the splicing I bought a small pack of the yellow IDEAL UY IDC connectors for 5 bucks (the yellow ones here: https://www.homedepot.com/p/Ideal-IDC-Connector-Multi-Pack-UB-UR-UY-Standard-Package-4-Pack-of-25-85-960/302918233)

I didn't realize at the time how heavily it's recommended to use the dedicated crimping tool for these. The tool, at least that I saw at the store, was about 30 bucks. I would buy it but it seems very dedicated, and I may never need to use it again. I tested some 24awg wire I had laying around in the connector using just a pair of regular pliers, and got what appears to be a clean connection (using a multimeter continuity test).

If the splice failed it'd trigger the emergency email (the switch is normally closed, rising water opens it) which is the "safe" way to fail, and this itself isn't mission critical, and it only needs to carry a digital 3.3v signal - are regular pliers (and testing after making the splice) good enough for this application? Does anyone have experience with the splice failing later or intermittently?

Is there a solution for such small wire that doesn't need crimping? It appears nearly all wire nuts and other twist connectors that I can find only go down to 22.

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  • \$\begingroup\$ why not solder and heat shrink? that's what i like for permanent splices. \$\endgroup\$
    – user156429
    Commented Feb 13, 2019 at 20:37
  • \$\begingroup\$ Well, the same frugality keeping me from just buying the dedicated crimping tool since I don't own any soldering equipment. I may end up going the soldering route since I am more likely to get future use out of a soldering iron. \$\endgroup\$
    – mock_blatt
    Commented Feb 13, 2019 at 20:47
  • \$\begingroup\$ @mock_blatt Get yourself a decent iron, not one of the $20 pieces of junk you can find at home depot. You'll be glad you did later, if you use it very much. \$\endgroup\$
    – Hearth
    Commented Feb 13, 2019 at 21:46
  • \$\begingroup\$ If you're going use a monitoring system with this many failure modes (particularly putting a pi in there) you probably need to do a periodic "all is well" message and generate a warning or maintenance request email in the cloud if that is not received after a couple times the expected interval. \$\endgroup\$
    – Chris Stratton
    Commented Feb 13, 2019 at 21:53
  • \$\begingroup\$ @ChrisStratton Yes I have a reliable home server I normally use for backups, I was thinking of having that listen for a message. Maybe have the pi periodically write a log to it, and the server checks for that log. A missing log or two and I send out another alert. I won't pretend this isn't primarily an excuse to do some fiddling around, so might as well throw some light linux shell scripting in there! \$\endgroup\$
    – mock_blatt
    Commented Feb 13, 2019 at 22:05

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You do NOT need the dedicated crimp tool for these splices. What you need is something that will close with the jaws parallel at the proper gap distance.

A pair of ordinary slip-joint pliers works well when you have the pliers set for the larger gap size. Add a shim of some sort if the gap is too large when the jaws are parallel. The smaller slip-joint pliers that I use have a gap that is just about bang-on. The larger slip-joint pliers are used with a small piece of 1/16" PCB material as a shim.

I actually do own the proper crimp tool for these connectors. But I rarely use it - the slip-joint pliers are usually close at hand whereas the proper crimp tool is put away in another building.

All that said: you shouldn't use these in a location where they might get wet UNLESS you have the grease-filled version. Although the grease-filled version is a standard item for telephone repair persons, I suspect that Home Depot doesn't sell them.

What I would do instead is simply twist and solder the conductors, then encase the connections with adhesive-lined heat-shrink tubing.

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  • \$\begingroup\$ Yes, I think I'll stop being lazy and just go buy a soldering kit. For what it's worth, the back of the connector box I've got says "with moisture sealant" - I guess that's not the same as the waterproof gel-filled ones. \$\endgroup\$
    – mock_blatt
    Commented Feb 13, 2019 at 21:23

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