After the power installation was done and working i started to think about how to connect the sensors i had in mind to the Raspi. It should be easy to connect / disconnect and allow at least eight sensors (each - 1W and I2C). So i came up with this simple adapter design additiona pinhead connectors will be added in a row on the device side. On the left side i have built the 1W side with a simple pullup resistor 4.7KOhm to the data pin (GPIO4), 3.3V and GND

On the right side i built the I2C adapter - the GND and 3.3V i connected from the 1W side + SDA and SCL connectors. That is it - the 1W was tested with a DS18B20 sensor which proved to be working...