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Wiring sizes and amps

Started by Adbrig4, January 09, 2022, 10:29:19 AM

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Adbrig4

Hello, has anyone used the automotive wiring size charts for figuring out wiring sizes for power injection?

k6ccc

This is the chart I use for calculating voltage drop on wire:
http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.html
I would take an automotive chart with a grain of salt.  Most factory automotive wiring is pretty dismal for anything that draws much current.
Using LOR (mostly SuperStar) for all sequencing - using FPP only to drive P5 and P10 panels.
My show website:  http://newburghlights.org

Jim

Adbrig4

Ok, I was thinking of running some of my smaller Coro props I put out though out the year around 50 to 100 nodes through 14/3 Romex about 50 feet through the attic and out the eve from the garage. I didn't know if that would be a good idea or not?

Thanks,Adam.

k6ccc

Personally I would not use Romex.  It's comparitively expensive, and overkill for your purpose, and being solid wire, it's stiff and harder to work with.
18AWG zip cord would likely be plenty, and with the longer runs, maybe 16AWG.  I have used 16AWB speaker wire from Monoprice.com for longer runs.  It's four conductor - which of course most pixels don't need the 4th wire, but I was mostly using it for dumb RGB.
Using LOR (mostly SuperStar) for all sequencing - using FPP only to drive P5 and P10 panels.
My show website:  http://newburghlights.org

Jim

pck

I found some heavy duty outdoor 14/3 extension cords at Homedepot on the clearance isle. 100' for $39. I tried running my 25X30 matrix and a window frame (900 pixels) on the full length hoping I wouldn't have to cut it but at 30% brightness some of the pixels didn't cooperate. I cut it in half and it seemed to work just fine.

k6ccc

#5
The wiring in the pixel strings are not going to support that long of a string.  The wire size on most pixel strings is pretty small, so it does not matter how much current is available at the source end, you simply are not going to be able to power a really long string without power injection.
Here is a good reference for understanding it:
http://spikerlights.com/calcpower.aspx
Using LOR (mostly SuperStar) for all sequencing - using FPP only to drive P5 and P10 panels.
My show website:  http://newburghlights.org

Jim

Adbrig4

Is there a recommended limit on amps and how many pixels you can run on a 50 foot 14/3 gauge cable?

pixelpuppy

Quote from: k6ccc on January 10, 2022, 08:23:18 PMThe wiring in the pixel strings are not going to support that long of a string.  The wire size on most pixel strings is pretty small, so it does not matter how much current is available at the source end, you simply are not going to be able to power a really long string without power injection.

That says it all.  Very basic, fundamental truth that everyone in this hobby needs to understand.  I see posts almost daily that indicate a large amount of hobbyist do not understand this.  Everyone needs to understand this.   ;D
-Mark

k6ccc

Thanks Mark.  I get something right once in a while...
Using LOR (mostly SuperStar) for all sequencing - using FPP only to drive P5 and P10 panels.
My show website:  http://newburghlights.org

Jim

Adbrig4

Sorry. I misunderstood this. It's more about the data signal transmission than amps through the cable. So the controllers really need to be as close to the props or pixels as possible. Thank you.

k6ccc

Yes, the controller needs to be fairly close to the first pixel.  How close that is does depend on length, pixel types, and even the wire in use.  For example, GE Color Effects pixels run at a fairly low data rate and can run quite long distance (at least close to 100 feet).  WS2801 pixels are very short (never used any, but I understand they are on the order of 5 feet).  These days, WS2811 pixels are very commonly used and you are usually safe at 20 feet.  Beyond that, test it with the actual pixels and wiring you will be using.  Hint, test on a longer distance you plan to use.  For example, if you need to operate at 30 feet and you test it at 30 feet and it works, what you may not know is that it only works to 31 feet and as soon as the wire degrades it now works to only 29 feet and your prop fails.  If you tested to 40 feet and it works, you have some margin for degradation.
Using LOR (mostly SuperStar) for all sequencing - using FPP only to drive P5 and P10 panels.
My show website:  http://newburghlights.org

Jim

pck

Adbrig4


While I agree with everyone's comments above, we all may be confusing you a bit. What's important is to get 4-5 volts to each pixel and a strong data signal to the start of your string.

This can be accomplished a variety of ways. It just comes down to what's practical for your own situation. You can use romex, landscape lighting wire, heavy gauge extension cord (my favorite), or pre-made cables for the power source to your strings. The data cable can be a smaller gauge wire and can be run longer distances. The data cable and power cables do not have to be run together, just make sure both are using a common ground. Your controller (supplies the data signal) does not need to be located at the same place your pixel power supply is at. The low voltage (especially 5V pixels) and high current demand of a lot of pixels becomes a big issue with wire size and distance. As your load increases (more pixels) the greater your voltage losses become. The three main voltages you need to be working with are 5V & 12V (depending on your pixel specifications) and the 120V ac power for you low voltage power supplies. You may want to consider keeping your controller where its easily accessible and just moving your power supplies closer to the props. Extension cords for the power supplies are cheap and readily available and their higher supply (120VAC) voltage allows longer runs.

You do not need to provide power injection for each string directly from the power supply (you can if you want). I build my power injection in at the prop. I wire each string to a common connector at the prop. In my case I have a matrix of (5) (in series) 5 meter 5V pixel strings (150 ea X 5 strings for 750 pixels) covering a window on the second floor. Jim is correct, you can't apply 5V power at the first pixel and expect it to be high enough at the 750th pixel. The data signal is only needed at the first pixel and has no problem making it to the end because its regenerated from pixel to pixel in series from the first pixel to the last (providing each pixel has 4-5 volts dc power). When I wired the matrix I provided separate power wires (16ga) to each of the 5 strings to a common connector (power injection). I have my controller in the garage and a 5VDC power supply under my eaves above the garage door. The data cables from the controller meet at the power supply junction box via cat5 cable (about 40') and grounds are tied together with the power supply. I then distribute power and data via 14/3 extension cords from the junction box to various props on the roof. The matrix is on a 50' run of that extension cord and works perfectly at 30% brightness. Next year I'll probably turn the brightness down a little as it was just too bright for me.

I use left over pixel strip pieces to light inflatables in the lawn powered by cheap usb chargers. I send data and ground from the controller on 18ga 2-conductor wire. I've gone over a hundred feet on the data wire without any issues.

Jim makes a really good point about testing your setups before committing to a permanent install.  I have purchased pixel strips and strings at various times from various vendors and they are all different. Once I figure out how many pixels I need for a prop I use various length extensions cords to test how far I can go before I notice a degragation. Of course you can use wire size charts and do the math. I started with that but my actual results always came out differently. I think there are just too many variables such as wire quality and size by the manufacturer, solder connections, cascading voltage drop from pixel to pixel, etc. I have seen a lot of people use 11ma per pixel as a rule of thumb and its not too far off. If you read the specifications for the pixels it will be much higher because its based on having 5 volts available at each pixel. That's never going to happen unless you power inject at each pixel which of course is not pratical or necessary. Each pixel following the power injection point will have a slightly lower voltage until you inject again. I built in a WiFi power meter into my power supplies that reports to a HomeAssistant web server which allowed me to monitor voltage, currrent, and temperature at the supply. My props ran at 30% brightness (Falcon controller test white setting) and averaged at 9-10 ma each. While my sequence was running it averaged closer to 4ma per pixel.

I hope this helped a bit.

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