I finished this few weeks ago and I kinda forgot it. Plan was to make a DIY -type box which encases every "sensitive" parts of the observatory. I decided to isolate that to make sure that temperature inside the box would remain above 0°C. I didn't put there any heater because I thought that two electrical inverters (220V to 12V) would do the trick. I made it quite wide to ensure that everything would have enough room, so the final size was 50:50:40cm.
Lower part includes electronic equipment. Bigger inverter (silver one) is Meanwell's and provides 12V and 150W which actually is more than enough for my equipment (I calculated about 9A), but I had older 5A inverter which I put also inside to feed power to dew-heater. There is also two transformers which provides 5V to Icron's 4-port USB Ranger and an active USB-hub.
And in the upper part is mainly "communications". From the left: USB Ranger, QHY9 power supply (front), wireless gamepad's receiver (black lying above wires), 2-port USB to RS-232 (just right of QHY) and the USB hub.
There's a lot of wires going to the walls behind and beside the USB-hub. They are part of 12V system which I made. I wanted to put most valuable things behind a separate fuses, and the cheapest and easiest way was to use a electrical box of a boat (cost about 20€). That also allows me to use everything separately by selecting equipment which will be powered. This was very useful when I had that motor problem in the mount. I could disable the power input to the mount just by using switch.
There are fuses and power switches to the mount, to both cameras and to QHY's filter wheel (which relays the power to RoboFocus).
And the isolation of the box works perfectly! Picture is taken with phone so it's really awful... But the temperature inside is +5.3°C even though there was almost -25 outside.