Normally I don't really get into safety considerations all that often. However, when you deal with electricity you might get a fire if you don't adhere to some considerations. Just because you have equipment that is UL certified does not mean that it will be UL certified when the equipment is put together (that is a whole another process). I can safely say that I will take all the precautions that I can, but there is always the possibility that the item may heat up too much. So thermal considerations will be an issue. I therefore need to consider what kinds of current and resulting heat signatures will come forth out of this project. I am confident that whatever I come up with will be contained in my rack and isolated from the rest of the apartment - but I still need to be aware of what the temperature in the rack will be.
So lets talk about sizing for instance. I will need to have at least 8 outlets for the power strip. That will include outlets, an 8 part relay blank, a Raspberry Pi, internal wiring, Power switch, and fuse to limit current that is drawn. When testing the setup, I can breadboard the whole thing and measure current draw and measure heat within the setup. There are a number of questions which I must answer before proceeding.
- What kind of current draw can I expect?
- Can I set up the Raspberry Pi as a trip wire for when voltage is removed and brought back up?
- Can the Raspberry Pi be used as a mechanism to shutdown / restart elements of the rack when power is restored?
- How will I do the interface to the 8 part relay blank from the Raspberry Pi?
- Will I need to have an MQTT server in the setup?
The Raspberry Pi 3 typically draws between 300mA and 400mA at idle, but can reach 1.3A to 1.5A under heavy load with connected USB peripherals. While a 2.5A power supply is recommended to provide sufficient power for the board and USB devices, the board itself usually pulls less, rarely exceeding 1.3A in typical, high-load use cases. (AI generated)
- Idle Usage: ~250mA – 300mA (with Ethernet).
- Active Load (Stress): ~720mA – 950mA.
- Max Recommended PSU: 5V at 2.5A (to ensure enough for USB devices).
