Conductor sizing, and stranded vs solid

Energy
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So I’m getting this RGB+WW+CW single pixel strip and this WiFi controller I’m going to flash to ESPHome to control it, for some under counter lighting for now, and in the future probably additional accent/etc lighting around here and there.

However, the cupboards are in 2 sections, and while I suppose I could have 2 separate runs/sections, just makes sense to have a single one. So I’m looking around for some 6 conductor, preferably white jacked (or I’ll just get some white shrink tube and use that over top).

I found some 22/6 stranded already in white, some 18/6 solid but in brown, and some 18/6 stranded already in white (don’t need plenum, but that’s what this is), or this 18/6 in gray or white, whatever they send me, or 18/6 or 20/6 in black.

For length needed, I expect something like 3-5 feet, probably max, wherever I might need to have a split on the strip. And I don’t think I’ll need more than 1-2 meters on the other side of the wiring, which based on the description is peak 30W per meter, or ~2.5a per meter (12v). That’s worst case, I expect it to be probably closer to 15W per meter typical max, probably decently below that. So what gauge do you think I should get? I think the 5 individual color channels can be even smaller gauge, while the +12v would need to be the largest for worst-case. Or just have them all the same gauge would be easiest. I’m not too worried about voltage drop for distance, more that I don’t want to even come close to overheating/loading a wire and being a possible fire hazard.

And I can easily enough just buy separate wire and heatshrink tube and do it all by myself.

Past that, stranded or solid? I’m inclined towards solid, since once installed I won’t be moving anything around. And if I go solid, can I go slightly smaller, for overall smaller diameter?

All in all, I’m thinking I can probably just get the 18/6 solid in brown from above, and just get white heat-shrink to put over it. Or just get some 20 awg solid in 6 color, and the white heat-shrink and DIY? Or do you think I can get even crazier and go 22 awg solid? I think that’s getting too small myself, if I ever trend towards the upper end of possible power use, even if solid.

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18 should be fine for the high current one, 20 for the smaller ones (though I’d probably use 18 if it would fit), and I don’t think 22AWG is a good idea. It might work, but… eh. Getting too close to the edge.

If stuff is firmly fixed, solid is fine, otherwise save your sanity and go with stranded. Stranded solders to pads a bit better, too.

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I agree with @syonyk, even for relatively low current runs it’s preferable to go on the larger side with the wire. I can’t stand using solid wire in an install - over time it can get brittle and then poof you have an intermittent connection suddenly and I’ve seen this happen even with solidly fixed installs from what I assume are thermal stresses over the seasons. Stranded, even if it gets brittle, has a comparatively lower chance of breaking from it and greater chance that the individual strands won’t all break in the same place. And yes, it’s easier to solder and work with in general.

I’ve not done programming work with the ESP8266 chips, but they’re fairly popular so you shouldn’t have much trouble with that side of it if you stick with the tried and true projects out there. That said, they’re not as popular as Arduinos or ARM based projects like Teensy, and they seem to be fading out to the wave of recent tiny, cheap, and fast ARM chips, so do consider that in your decision process.

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Thinking through some projects where I used solid assuming it would be fine, then wasn’t over time, yeah… just use stranded. Also, if you’re under-gauge for the current, you can always parallel a few runs of stranded between connections. I’m pretty sure my office lighting setup (which is a couple LED strips, wired up similarly) has one of the runs with a couple bits of stranded wire twisted together and paralleled.

I’ve used ESP8266s for wifi-over-serial, but not as standalone controllers, though I understand they’re pretty good at it.

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OK, decided to get a 6-color/spool 5m spools pack of 18 awg stranded, and 3:1 white heatshrink with adhesive lining. That’ll work, and give me other options in the future.

As for programming it, that’s what ESPHome is for. Already have it all programmed in, just need to provide some YAML and it’ll configure itself, broadcast to find the HomeAssistant server, etc. Even already has the RGB WW/CW component with color wheel control/etc.

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Nice, that works! I love those little colored bundles, used to buy them at Radio Shack. Just check loaded temperatures before you bundle stuff together - it shouldn’t be an issue on 18AWG, but bundles of wires are usually rated for less current than the same wires, separated by airspace, because of heat dissipation.

Solid wire is great for building your own breadboard jumpers, though!

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A rule of thumb I use for this without looking up resistance vs gauge charts and doing math is that standard 10A wall outlet power cords are 18 gauge stranded for two meters. So I wouldn’t worry about 20 gauge at all. You bought 18… so zero things to worry about there.

You won’t ever be running it anywhere near full current. 3 meters at its peak of all five leds on with no PWM would be crazy bright and not a desired look. In reality you’ll (a) never drive any of the LEDs at their peak, and never drive all five of them at once. Planning for 40% peak is more than enough.

What bothers me with such assumptions is that it all depends on the software and hardware working properly. When any of that fails they could all wind up at 100% full on. But that rare chance is what fuses are for. Does anyone ever actually puts those in their own designs anymore? :stuck_out_tongue:

I’m curious if you hear any audible PWM noise from that controller and the specific power supply you choose to use.

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But of course! It’s just the un-replaceable surface mount version underneath a layer of potting in the glued-together enclosure you can’t open; thereby rendering the device forever safe by bricking it completely if anything goes wrong. :crazy_face:

At least with my own PCB designs I like those solder-in socket for the mini automotive fuses. Never without them on a project that sees an AC input. Getting better about putting them in other designs.

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Sure, 22AWG interconnects serve the purpose very well! :slight_smile:

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In my personal experience the circuit blows to protect the fuse… :wink:

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Just got the controller device, nice little ESP, VERY easy pry open with just my fingernails. Has 5 N-chan MOSFET, up to 30v so no problem with the 12-24v that it says it can handle, and while I’m not very skilled at reading these data sheets, looks like the switching time is in 10s of ns, and should be able to handle the high frequency PWM just fine. And appears like they should handle the rated 4a per channel just fine, as long as they don’t overheat. Which I don’t expect will be an issue for me.

It has a spot with what appears to be an external antenna, but it doesn’t appear to be hooked up, correct? Should I bother trying to hook it up?

Also on the bottom it’s got the 3.3v, V-, IO, RX, TX pins brought out to pads and have a bit of solder already on them, so should be easy peasy for me to solder some leads onto those for the FTDI to flash it =D

led driver

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For posterity’s sake, here’s the details on setting it up via ESPHome in Home-Assistant.

So the controller is a 1MB flash ESP8265MOD M2 device. This is basically an ESP8266 with less flash memory, and maybe a few less pins.

There isn’t anything too specific on the ESPHome site about it (I need to go in and contribute some docs updates), but Adafruit to the rescue, I got the pinout. Tracked the pins to the input SMD resistor or capacitor, can’t tell which, at the top of each of the MOSFETs, for the right channel. After screwing it up, since the labeled image is upside down, and I messed that up for a while, finally got each channel correct in the configuration! Works great, although Home-Assistant card element I think I need to figure out how to get it to not try and use the RGB to mix in with the white when trying to just mix the white to cooler or warmer. But I think that’s just configuration. I may choose to use color_interlock setting to prevent RGB and White LEDs from being on at the same time, Although I do kinda want the option to mix them, might just not be all that good an idea.

I also realized when I opened the LED strip, that I got ones with the epoxy top to make it waterproof, not bare LED strip which is what I meant to get. I’ll see how well it fits into the LED strip channel with diffusor I have coming, since I do want to diffuse to get a more consistent strip of white/color. On the whole, I’m happy with it! I’m getting the full set of wires and heatshrink tomorrow, and unfortunately all the way to Friday for the channel. Ah well.

It’s also up and running on the IoT VLAN, as is HA (plus HA is on my ‘LAN’ VLAN), so that configuration is all working! Yay!

esphome:
  name: kitchen_led_strip1
  platform: ESP8266
  board: esp8285

wifi:
  ssid: "<SSID>"
  password: "<PASSWORD>"

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Kitchen Led Strip1"
    password: "<HOTSPOT PASSWORD>"

captive_portal:

# Enable logging
logger:

# Enable Home Assistant API
api:
  password: "<API PASSWORD>"

ota:
  password: "<OTA PASSWORD>"

output:
  - platform: esp8266_pwm
    id: output_red
    pin: GPIO14
    max_power: 80%
  - platform: esp8266_pwm
    id: output_green
    pin: GPIO12
    max_power: 80%
  - platform: esp8266_pwm
    id: output_blue
    pin: GPIO13
    max_power: 80%
  - platform: esp8266_pwm
    id: output_cw
    pin: GPIO5
    max_power: 80%
  - platform: esp8266_pwm
    id: output_ww
    pin: GPIO15
    max_power: 80%
    
light:
  - platform: rgbww
    name: "Kitchen Cabinet Lights"
    red: output_red
    green: output_green
    blue: output_blue
    cold_white: output_cw
    warm_white: output_ww
    cold_white_color_temperature: 6350 K
    warm_white_color_temperature: 3400 K
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Which spot? If it works, I wouldn’t mess with it. The ESP has a PCB antenna too, and I’ve no idea how those things interact with each other. That looks a very general purpose board, and the capacitor spots are cute…

What’s the concern with white + colored LEDs on all at once? Current/thermal? Being able to adjust the color temperature with the bulk of the lumens coming from white seems very useful to me.

Man, now I want to get around to building my multi-color room lights…

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You can usually either cut a trace or de-solder a jumper on such boards that have a PCB antenna and an external antenna socket. IIRC the raspberry pi has an IPX connector pad, and an 0402 jumper that would select between that or the onboard PCB antenna.

I wouldn’t bother with an external unless you find you need the range wherever this thing gets installed; also don’t run both at the same time.

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RE: Antenna, yeah, probably just better to leave whatever is there alone. Even if it isn’t hooked up, I’m not at the edge of WiFi, so no need to try and optimize the RF for making a good enough connection. In reading some of the Amazon reviews/questions/responses, looks like there was an earlier version that had a different MCU which might have needed that antenna. Might have just left the board design alone and just not hookup the antenna or something.

RE: White + colored at once, it’s not current/thermal, more about color temp and such. More mixing the 2 colors of white, to get the bulk of the light/color-temp, rather than mixing in the RGB colors along with 1 of the white channels. Mostly just “how pleasing does this light look to me”, so I’ll wait to do significant messing until I get the channel and see how things look in it, held more or less into place via tape temporarily to see how things look. I might find that it doesn’t make much of a visual difference to me, so why bother trying to ‘optimize’ that away.

I suspect that that’s a HA control thing, rather than a ESPHome settings. Something for me to investigate anyways.

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So got the aluminum channels. And realized I don’t have a good way to cut them. I’ve got a reciprocating saw and blades…but that’ll make a MESS of the end, and I want a reasonably clean cut. So time to buy a hacksaw.

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I’ve cut aluminium with a carbide finish blade on a skilsaw or chop saw just fine, 90+ tooth. Just go slowly and wear glasses and gloves. I route the stuff too.

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I don’t have any finish blades, I have an 80T and 44T for my 12" miter saw. I mean, the 80T is a “finish” blade, but that’s more on wood than metal.

So I’d need to buy another blade, instead I might as well buy a small hacksaw. A lot cheaper too, compared to a 12" miter blade. Won’t take me long, and probably just as handy to have around for possible future uses. Doesn’t take up a ton of space in the toolbox either.

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I disagree. I cut an awful lot of Iron Ridge rails with exactly that setup and it was quite clean, if you take your time and don’t force it.

There’s no real difference between that and a hacksaw.

Do a test cut, but I think you’ll be fine with that arrangement and it’s far faster than a manual hacksaw. I did exactly one rail with a hacksaw, then said “This is stupid” and used my recip saw and blade for the other 23 cuts.

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80t will probably be fine. I was using a 15" blade.