Wire choice

Good morning,

As I gain experience with the intricacies of outdoor cabling and power supply location, I will be situating several external runs of ws2811. Most will be shielded from direct view and will bounce light off an eave and soffit to produce reflected light. The setup protects cable runs and LEDs directly, but in high winds (often the case) there is some misting.

I am considering using a 16/3 extension cord cut into lengths <4 m to power and signal the LEDs, and have adopted raywu pigtails. Such conductors are robust, and easy to work with. I had used 18g 3 conductor wire, but the signal occasionally becomes flaky >3 m. I have tested the 16/3 cord and line losses are minimal up to 5 m (on the workbench). Thoughts or suggestions are welcome.

For longer runs I highly recommend you change your “mind view” about your installation.
There are two things that need to be supplied to your strip setup: Power and Data.
They have different requirements especially when dealing with longer runs.

Power is pretty well defined by Ohm’s law, you figure out the maximum current your strip will need at various distances around the setup and use wire that’s big enough so as to not add too much resistance/cause a voltage drop.

Data is completely different, it needs almost no power and is “regenerated” by every LED that gets proper data and power.

I suggest you make this distinction because your choice of 16/3 implies you’d like to run a single cable supplying power and data to your setup - the 3rd wire being the data line while the other 2 are power.

Your bench setup shows that 16AWG wire is suitable for the voltage/current/distances you anticipate and in general that’s probably a good wire choice. Power seems to be reasonably handled.

Unfortunately data is another matter, linking your data line via the “3rd” wire may work out OK in your setup, but maybe not. I’m very leery of coupling a data line alongside your power lines which is what a 16/3 cable will do. The chance for injection noise in that data stream is greatly increased, it typically shows up as sporadic flashing or flickering for no apparent reason.

You might be able to get away with it and there are a raft of resistor/mid span signal boosters/level shifters that might help. But to have a reliable long term setup, dedicate a separate wire for the data line (actually Data and Ground) and do what you have to do to make that work for you. You’ll likely need a level shifter and/or if the distance to the MCU becomes great enough a differential TxRx board pair.

Thank you for the in depth reply. I will factor your observations into my decision.

I put my theory to action and was not disappointed. Voltage drop across 3 m from the Diguno to the pigtail over 16/3 extension cord was 0.14VDC, only half of the drop using 18/3 wire. There is no signal degradation. I plan to power the next run with 12V LEDs, and I expect even better performance.

Thank you