It is against building codes in most countries to run low voltage cable (ie ethenet cable) in the same conduit as electrical power cables.
This is more of a safety thing. If something happens to the wires and power gets into the ethernet cable you can get shocked because there is no protection on ethernet. People are also not as careful because the never suspect there could be deadly power on ethernet.
Although you might get interference power runs at 50-60hz where data is being transferred at frequencies in the hundreds of mega hz. More the problem is the power might induce a current in the ethernet than can damage equipment even though that is highly unlikely.
Hard to say what will happen for sure since this is a...