SparkFun Electronics Forum

I have a project in mind where I want to use I2C to communicate from a Main unit that has the Arduino Controller as the Master and connect to it Slave units that have their own power sources / supplies and grounds etc... Basically I want to use just the two serial lines and not pass the 5V or Ground along with it.

Will this work or so I need to have a common single 5V source and ground for all Slaves coming from the Master?

I'm new to the I2C realm...

Here is a little more detail. The Master may be in one location and the Slave in another. Each having their own 110V AC source and internal supplies to provide the DC. It is also quite possible that the 110V AC source may come from different locations / homes. I was going to use I2C Differential Extenders to deal with the distance issues between Master and Slave units.

Thanks,
Rich

Well, this device in particular:
http://sandboxelectronics.com/?p=1098
says:

GND: (optional) GND. As the communication is differential, there is no need to share a command ground across the wire, especially when the two systems across the wire are at different ground levels.
VBUS: (optional) Power supply output of the on-board DC-DC converter