Recommended wire gauge for micro-controller projects

[Youkai]

I'm considering buying some new spools of wire since I learned about silicone coated wire. If I'm going to be buying new wires anyway I want to make sure I get the right gauge.

The types of projects I usually work on use Ardiuino compatible micro-controllers, servos, and LED strips like DotStar/NeoPixel. Those being the case what's the recommended size.

I'm sure a few gauges will work but is there a "rule of thumb" about them. Is bigger better, thinner, the middle of the road? I imagine thinner wires are more flexible but can handle less current. Is the amount of current you would use to run a meter of LED strip negligible compared to the amount of current that even a thin gauge wire could handle? Are thinner wires harder to work with than thicker?

Also any recommendations for good online marketplaces to get wire for a decent price (shipping to the US).

Thanks for your suggestions.

[ledtester]

I don't think there is one recommended wire gauge -- like everything in engineering there are trade-offs to weigh.

First you should distinguish between sold-core and stranded wire. Stranded wire can survive a lot more bending and handling -- think of your multimeter cables or power cords. The drawback is that they will be thicker for the same amount of current capacity. Solid core wire generally appears inside enclosures and are not directly handled by people -- think of the wires carrying mains current inside the walls of your home. They are generally thinner for the same amount of current capacity.

The gauge generally depends on the amount of current you need the wire to carry. For digital signals you generally can get by with very small gauge wire but for larger currents you'll need thicker wires. For instance, in a PC consider the difference between the wires in ribbon cable vs. the wires which carry power from an ATX power supply.

For long runs of wire the resistance per meter (or foot) is also a consideration.

There are charts which will tell you the current carrying capacity and resistance per length of various wire gauges. For example, here's such a chart for American Wire Gauge (AWG) sizes:

https://www.engineeringtoolbox.com/wire-gauges-d_419.html

[james_s]

If you want to work with solderless breadboards you want solid core wire, IIRC typically #22 fits nicely. For almost everything else, stranded wire will be preferable. I use two different sizes for most of my projects, #20 for power connections and #24 for signal wires and low power stuff like LEDs. There are exceptions where heavier wire is needed but if I could only have two I would get #20 and either #24 or #26.

A great source of project wire is to find an old parallel printer cable or 25 pin serial cable and cut it up. You can still find those for next to nothing and even a grimy dirty beat up one will give you a nice bundle of pristine wires in a rainbow of colors when you strip off the outer insulation.

[ledtester]

Here is an example of the different solid core gauges I use:





The jumpers on the front side are from telephone cable. A lot of people say 22 AWG solid core works well in breadboards but you might find they are a little too thick to use in protoboards which is why I like the modular telephone wire. And you get four colors - red, black, yellow and green.

The wires on the back side are 30 AWG solid core. This particular wire doesn't have the kind of jacket you find in Kynar wire -- it's more of a PVC jacket, but Kynar wire would probably work just as well. I use the 30 AWG for higher density connections. One advantage of solid core wires is that you can form them into a specific shape and they'll stay that way.

As james_s mentioned, old Centronics printer cables are a good source of small gauge typically stranded wire. And you get a variety of colors.

Old ethernet cables is another source of solid core, multi-color wires which can be used for general hook-up purposes.

[ledtester]

And another useful kind of wire to have is red-black zip cord.

[tooki]

My go-to wire is 24AWG solid for perfboard builds, and 24AWG stranded for everything else. But of course I’ll use other wires as needed.

For test leads, I use silicone wire of various gauges.

I don’t advise using telephone wire for anything soldered for the simple reason that in my experience, the insulation melts at extremely low temperatures, so unless you’re experienced enough at soldering to do it extremely quickly, it just turns into a mess.

If you happen to live anywhere near Los Angeles, go to Apex Surplus in Sun Valley. There you can buy surplus military-grade wire for pennies on the dollar. That stuff is wonderful to work with: the stranding twist doesn’t fray as easily, and the insulation is more resistant to heat. (The downside is that the insulation is a bit harder to strip.)

[sleemanj]

20AWG silicone
30AWG silicone
Tinned copper buswire
Bare copper pulled from scrap cat-5 cable or similar when I can't find what I did with the tinned buswire
Solderable enable wire comes in handy for pcb bodge

Not much a fan of normal pvc wire where it is not required, silicone is so much nicer to work with.

[Doctorandus_P]

Connections for logic between IC's I usually do with 0.2mm (diameter) "enameled" wire. This stuff is good upto about 200mA and you can fit a lot of them on a PCB. You can also easily poke 7 of them though a single hole.
For higher current, scale up accordingly. The three main factors that determine wire diameter are:

* Current handling capability (before the wire gets too hot).
There are tables for this, but it's usually thing wire so oversizing it a bit hardly costs anything.

* Voltage drop. (not such a problem for digital stuff, but can be important for analog stuff).
When working with matrix board, it's also easy to use star points, to prevent voltage drops in one wire being picked up by some other sensitive input. Just give each connection it's own wire straight from whatever the output is.

* Mechanical strength.
When you route wires off-pcb you may want to use thicker wires just for mechanical strength.

[Ian.M]

Soldering stranded wire to a PCB is a PITA, so once resistance and ampacity are satisfied, it usually comes down to what wide sizes do you have connectors and (preferably crimp) tooling for?  One size does not suit all - e.g. you may well choose to use 0.1" pitch headers for IDC or DuPont connectors with thin wire for signal wiring, but need something much heavier e.g. PCB mount 1/4" blade connectors for power.