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These wires will carry up to 1.5A at 5V outdoors in clear weather. Would it be reasonable to connect them by simply taping them together with electrical tape?

I'm new to electronics outside of embedded programming and simple Arduino prototyping, so I wanted to check that I'm not running into any safety issues. Hope this is on topic and not too basic.

enter image description here

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  • \$\begingroup\$ Are you going to be connecting many wires like those? \$\endgroup\$ – Andrew Morton Jun 26 '18 at 12:48
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    \$\begingroup\$ If you need them to be disconnectable then some sort of plug and socket would be in order, or if not then Wago connectors are easy to use, or choc block connectors might be useful for you. \$\endgroup\$ – Andrew Morton Jun 26 '18 at 12:51
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    \$\begingroup\$ What is the guage of the wires, and how long will the wires be? It's pretty hard to comment on the safety or practicality of your plan without that information. \$\endgroup\$ – Elliot Alderson Jun 26 '18 at 14:05
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    \$\begingroup\$ Re: "simply taping them together" -- no, never. That won't create a tight, low-resistance connection, and sooner or later they'll come apart. \$\endgroup\$ – Pete Becker Jun 27 '18 at 12:11
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    \$\begingroup\$ What do you mean by "outdoors in clear weather" ? That there is zero chance this device will ever by outdoors when a cloudburst happens? I strongly recommend only using outdoor-rated wires and connectors regardless of your faith in the weather. \$\endgroup\$ – Carl Witthoft Jun 27 '18 at 15:36
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For a good connection that can withstand lots of movement/bending, use:

  • Solder
  • Crimp terminals (either permanent "butt" connectors, or male and female terminals if you want to connect and disconnect)
  • Screw terminals ("terminal block")

crimp terminals with crimp tool
(Image from pixabay.com)

screw terminal block
(Image from wikipedia.org)


For a more temporary connection that is quick to add/remove: Use spring-loaded terminals

spring wire terminal block
(Image from dhgate.com)


For a hack that will work in a pinch but destined to eventually fail under light abuse: Twist the wires together and add wire nuts or tape.

wire nuts
(Image from cnc-plus.de)

This is all under the preface of "clear weather" as you had stated. Note that while weather can be "clear", hidden moisture in the air can still accelerate corrosion/rust over time, depending on the metals involved. Corrosion can lead to shorts or opens.

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  • \$\begingroup\$ For wire nuts, you would want the smaller ones; blue or smaller. A yellow one is out of the question. Follow it with some electrical tape just to hold it together due to the small wires (you don't normally need to tape wirenuts on mains wiring); keeping weather out will be a lost cause. \$\endgroup\$ – Harper Jun 27 '18 at 16:47
  • \$\begingroup\$ For outdoor installation, for serviceability, safety, and specifically UV Exposure. I would use wire nuts or terminal block inside a junction box with passthrough glands for strain relief . \$\endgroup\$ – crasic Jun 28 '18 at 0:54
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I would solder them and then use three section of shrink-tube. One around each wire and after that a third one to cover all of them.

But then I happen to have a drawer full of shrink tube of various sizes so I don't have to buy some...

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    \$\begingroup\$ Heat shrink is not waterproof though. It's pretty good, but moisture will make its way up the heat shrink by capillary action; and then the heat shrink keeps the water in instead of out. It might slow the onset of corrosion, but it won't stop it. \$\endgroup\$ – Graham Jun 27 '18 at 0:23
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    \$\begingroup\$ Adhesive-lined heatshrink is totally waterproof. \$\endgroup\$ – mkeith Jun 27 '18 at 7:01
  • \$\begingroup\$ you can also stuff silicone grease into the heatshrink to keep the water out \$\endgroup\$ – user163177 Nov 25 '18 at 17:36
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Yes. Assuming these wires are not being moved or pulled apart, a rat-tail splice insulated by electrical tape is perfectly acceptable. However, if they are being pulled apart, you'll need something more.

enter image description here

You may very well get away with a western union splice with no solder if the wires are being lightly pulled apart, but this is risky so you should just apply solder anyway.

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  • \$\begingroup\$ Thank you! I had never heard o the western union splice, exciting that it's stronger than the individual wires! In my case, there will be no load stress but slight movement. I was mostly worried about fire/melting hazards. \$\endgroup\$ – Anna Jun 26 '18 at 13:55
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    \$\begingroup\$ It's stronger than the unspliced wire when it's been soldered. Don't expect an unsoldered splice to be stronger than the wire. \$\endgroup\$ – Dampmaskin Jun 26 '18 at 15:27
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    \$\begingroup\$ These splices are for single wires, aren't they? I don't think they make sense when one end is stranded. \$\endgroup\$ – leftaroundabout Jun 27 '18 at 10:26
  • \$\begingroup\$ @leftaroundabout They are fine to use with stranded wire. The "western union splice" is simply a variant of the double fishermans knot which is often used to join stranded and kernmantle ropes. However, for stranded wires you can make a more secure connection by spreading the wires and interleaving the individual strands together instead. \$\endgroup\$ – crasic Jun 28 '18 at 0:43
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You have a bunch of answers related to functionality, but at least one of your main concerns seems to be safety.

Personally I would solder the wires and insulate them (maybe heat shrink with internal adhesive to seal if there was power available- I have a butane soldering iron but not a butane heat gun). A wire nut or a couple layers of tape is okay for temporary use. Offset the connections (make one wire shorter than the other and vice versa for the other end) so that a short is more unlikely.

For safety you should make sure that the source is current-limited or fused at a current below the maximum the wires are rated for. If your wires are good for 8A, a 5A or 8A fuse will protect the wires from overheating if a short circuit occurs.

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    \$\begingroup\$ Thanks a lot for your input! I'll definitely look into fuses -- something obvious that I hadn't thought of. Also great idea about offsetting the wires, never would have come up with that myself. \$\endgroup\$ – Anna Jun 26 '18 at 14:52
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    \$\begingroup\$ If you're careful, you can shrink shrink-tube with just about any strong enough heat source. It's tricky to do with a soldering iron (must make sure it never touches the tube, of course!) and even then the result isn't optimally smooth, but it will still fulfill the protective role. \$\endgroup\$ – leftaroundabout Jun 27 '18 at 10:22
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You said "clear weather", but, outdoors anyway.... There are wire nuts you can buy that are made for outdoor/wet environments. They have silicone in them and the silicone squeezes out over the wires as you tighten the wire nut, thus weather-proofing the connection. You could use those and then electrical tape it afterward (or not). My landscaper used them on my 12V outdoor landscape lighting.

Search on "DryConn"... Home Depot site even has a video of their usage.

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If you have a soldering iron you could connect them with solder like this:

soldering

You have to tin the wires before, like this:

tin w

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    \$\begingroup\$ That crocodile clamp on that wire makes me flinch a little bit, even if it's just a ground wire. Damaging the insulation is way to easy that way \$\endgroup\$ – Pelle Jun 27 '18 at 9:59
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    \$\begingroup\$ @Pelle yeah, it's a good idea to wrap the jaws of croc-clamps on a helping-hand stand in tape or shrink-tube. \$\endgroup\$ – leftaroundabout Jun 27 '18 at 10:29
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    \$\begingroup\$ @Pelle probably used the alligator clamp on the earth wire while soldering all of them. Piercing the insulation of an earthing wire is not a code violation, they're not even required to be insulated, insulation is just there as a marker/disambiguator. Only exception is Aluminum earth wire in damp locations, there the insulation is the membrane that keeps water out. What makes me flinch is soldering mains wiring; definitely a Euro thing. \$\endgroup\$ – Harper Jun 27 '18 at 16:53
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    \$\begingroup\$ Since this is stranded to stranded joint. A much better bond can be made by intertwining the strands together and then soldering, instead of tinning the ends and soldering them like you have. This means you do not need to tin before splicing, and you avoid the "kink" in the wire from the tinned portion. Also, the cable lays flat without a bump and has superior mechanical strength- Much Cleaner! See this for an illustration \$\endgroup\$ – crasic Jun 28 '18 at 0:46
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There are many other good answers here, but I'd also suggest using a Chocbox:

https://en.wikipedia.org/wiki/Chocbox

https://www.screwfix.com/p/chocbox/54936

This provides a handy protective enclosure for the place the wires are joined.

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