Dear friends
I have to run 90 meters of cat5 cable and 70 meters of 12V DC cable (2x0.75mm2) together across my house.
I'm using the ethernet cable for 1-wire bus, and power cable to feed 1-wire controlled devices.
If I understood correctly, capacitance should be as low as possible in 1-wire networks to to allow longer wires and more reliability.
Is it right that shielded cat5 cables have more capacitance than unshielded?
If yes, would be useful to use a shielded power cable?
How do I have to handle shielding from an electrical standpoint? Do I have to ground it on one side or both sides? I suspect I have to pay attention to not completely destroy it when connecting devices along the cable
If you have not already read this, it might answer your questions
Hey MikMo
thank you for the link. I can almost tell that guide by heart!
Unfortunately it doesn't offer advices about wiring choices, except it recommends Cat5 cable.
However a quick Google search lead me to new surprising discoveries! 
Here http://www.btinternet.com/~jon00/onewireintro.shtml they say "When running a 1-wire bus, Dallas recommend that you use unshielded CAT5 cabling for the bus. However if you have few sensors and short runs, telephone cable will work just as well. Do not use shielded cable as the capacitance increase will upset the network."
They also talks about The Link, a 1-wire controller made by 3rd party company which is optimized for long networks.
If it's much better than standard Maxim DS9097R controller like they say, it would be great! 300 meters of Cat5 cable is a lot.
Do you suggest to use shielded power cables? A 12V 2A DC power supply requires at least 1.5mm2 copper section to reduce voltage drop on long distances and suspects it produces some EMI.
Can I use dual power supply at the end of the cables to minimize voltage drop or it's just a blasphemy? 
nobody has any advice on this?
As I need to use something like 80 metres of cable, I'd like to do a safe buy since it's going to cost more than 50 euros and since I'm not an electrician it would take forever to "recycle" it