No idea where to start

I need advise or a good solution:

I have 5 Cat5e cables running to my garden. I have a supply of 240v direct from a breaker on the consumer unit where the cat5e cables start.

I want to be able to power:

⁠Cat Animal Feeder - 12v - can be fitted with terminals so I can connect to cat5e

  • garden spot lights from Amazon - 12v - garden light connector which I’m not sure if there’s a terminal so might have to chop?

  • ⁠fairy lights - 12v - garden light connector which I’m not sure if there’s a terminal so might have to chop?

For now I will only use 2 cables and decide on the rest later, I want to know what smart switch I can use to control this?

Would Sonoff be suitable? and if there a connector for the garden light to cat5e?

I am not sure if I can connect 240v to sonoff and it would output 12v to the lights?

What sort of load are we talking about here (at 12V in Watts)?

Garden lights in particular sound like a load that would be far too large for individual Cat5 cable pairs. You will get significant heating and voltage drop. And Cat5 is most definitely not rated for 240V so you would be unable to put the 240V AC to 12V DC supply at the garden end.

Lets assume the worst case scenario and your cat5 cable is 26AWG (though it could be thicker 24AWG).

If you parallel up all your cat5 pairs, 5 x 6 x 24AWG = 30 x 0.14 = 4.2mm cross sectional area. Which would allow you this sort of distance depending on your lighting load:

Screenshot 2024-06-21 at 09-23-10 Austech Garden Lighting Cable 💧 SunshowerOnline

Keep in mind this is using all your cat5 pairs paralleled up.

It is possible to transfer significantly more power at a higher voltage (up to 60V on Cat5) as the loss is proportional to the square of the current and higher voltage = lower current for the same load. You can use some sort of voltage converter at either end.

So lets start with the load sizes (in W at 12V) and see if we can come up with a solution.

You’ll need something to convert 240AC to 12Vdc. Something like this would work.

Then get a shelly 1 as your switch. The shelly can run off either the 240Vac or 12Vdc. I’d use the 12V. To connect it to HA you’ll need wifi in the area.

120W at 12V is 10A. If the load is that big the Cat 5 cable will last a few seconds at most before bursting into flames.

Let’s find out a bit more about their actual load requirements before suggesting solutions.



Id add It needs to be able to power off of a standard PoE tap or not at all. I would not try to Jimmy rig cat 5 to carry power.

That said. - I’m sorry to say Im almost positive those garden spots overrun PoE with just one or two lamps. This doesn’t sound at all like a good idea.

I didn’t read the first part right. I though he had power at the far end. The lastest POE++ standard indicates you can run 71W on the line, but there are multiple devices that push a little more such as this one which does 95W.

Devices at both ends need to support it in order to have the correct power sent from the source.

At a significantly higher voltage than 12V. Read my bit above about current-voltage and power.