I need a PDU, in fact I need two of them. But they are expensive, they cost hundreds and hundreds of dollars, some even a thousand. I hunt for them on various second hand sites and I already found two, but I need more. So I made one for next to nothing... let me show you how.
So PDU stands for "Power Distribution Unit", it is basically just a power strip for computers. So you go to EBay, you enter "PDU" and you will see a bunch of power strips with rack mount ears that does not cost too much. In fact they are cheap... but...
You also want to monitor how much electricity you are using, so you type "metered PDU", why not... And that's a but different, costs more. And of course you want to turn the servers on and off remotely, because they are using electricity even after you done sudo poweroff, you want to save that, and so you type "switched PDU". And you want quality and you are not ready to experiment with the unknown here, so you type "APC switched PDU".
And that's it, those are expensive because they were expensive to begin with and when someone have them they are not replaced like old servers, they remain serving the next generation of the equipment.
But here is the Sonoff POW. It is a toy, it is cheap, it is practically a smart relay with wifi. You can buy one for less than $15. Well, they are not industrial grade, they are kind of a DIY IOT devices. But they work. I know, I tried many of them, in fact I have several of them in a big box so I can play any time I want. So here is what I did...
I bought an old metal box with sockets, a circuit breaker a switch and some electric noise filters. I had it for about $20. Then I took two Sonoff POW, I flashed them with the open source program called Tasmota and I just put them into the box where the filters were before. Took some time, but fortunately I have the tools, the wires and I am kinda familiar with electricity, so here it is, I made a wifi metered two bank 16A 240V PDU. For about $40, that is for less than tenth of the price.
Well, it is not as strong as an APC PDU, it can only handle 16A (well, two Sonoff can theoretically put out 32A, but the wiring and the breaker can only handle 16A), it doesn't have 16 or 24 switches in it, only have 2, but I made it. It will do until I find some APC PDUs and after it I still can use it to switch something on and off around the water-cooler... sonoff, get it? S-on-off... :D
I knew those wifi devices will work inside a metal casing. It is practically a Faraday cage, it is even grounded, but still, it works. The wifi signal just leaks through somehow.
And since I am already using a bunch of Sonoff devices around the house, I only needed a few seconds to put the new device into my Node-red page, they appeared, they measure, they switch. I connected a little electric teakettle, that's my dummy load, it is about the same as one server.
Well, it is 4A already, 16A won't be enough for much, but I just have the place for it. I better make an other one.