On Mon, Oct 21, 2024 at 9:03 AM <karl@???> wrote:
>
> olbigtenor:
> ...
> > For the LED light controls there is a three wire cable that comes off
> > the fixture.
> > I have been using 18-3 wire (sorry don't know what that is in the DIN
> > system) (called signal wire in the electrical trade) and that matches
> > the wiring on the fixture.
> ...
>
> Guess that is similar to tree wires of 0.75mm2 in a cable.

This online calculator ( https://www.rapidtables.com/calc/wire/awg-to-mm.html )
gives it as 1.0237 mm2 but this is not an area of my knowing much so - - - .
>
> ///
>
> The inportant things to consider:
>
> Power lines:
> voltage drop due current flow, you want sufficient voltage
> at the end of the cable.
>
> Signal lines:
> let tr = the fastest rise time from 10% to 90% of the signals top voltage
>
> (then fn = the knee frequency = 0.5/tr
> the knee frequency is a crude estimate of the highest frequency
> content in your signal)
>
> v = signal velocity in the cable is about 0.6 * c
> where c = speed of light in vacuum
>
> l = lenght of the rising edge in the cable = Tr * v
>
> if cable length < l/6
> then the cable can be treated as a lumped circuit
> else it has to be treated as a transmission line
>
> if transmission line the cable has to be treated with care,
> no sharp bends, no bad connections, no deformed parts
>
> ///
>
> Always use a suitable terminator matching the cable impedance.
> Beware of
> incident elecromagnetic interference, electromagnetic emmisions,
> UV-light, heigh/low temperature, vibrations, mechanical forces.
> excessive moisture, fungus, rats chewing on cables,
> earth voltage differences ...
>

In other words - - - - good luck in the real world. The wire will be in conduit
and the T ranges from -40 to 45 C (bottom rarely - - top possible but
I hope not!!).
moisture - - - its in a building that houses animals so moisture is a given!
Rats - - - are you referring to two or four legged types? (grin - - -
there are both
in abundance!!)

> ///
>
> UTP is useful up to 250Mbps per pair
> 150Ohm STP-A upto 1Gpbs
> Coax beyond 1Gbps
>
> For long streaches, there is coax cables with low attenuation.

I'm looking at 50 m max length before the cabling will hit another
either microcontroller
or some kind of microprocessor.
>
> ///
>
> For you I guess outdoor utp cable will suit you well.
> They are usually black and heavier than indoor cable, use
> stranded version where there are vibrations.
>
> Where there is vibration, use rubber cable with fine stranded
> conductors, so use outdoor installation cable upto near you
> fans ending in a connection box, and from there a flexible
> rubber cable the last meter (for the power), and just as well
> a safety switch instead of the connection box.
>
Thanks for the information mr Karl!!