Power and Data in same conduit?

[Paul_C]

Sound advice, but all Base-T Ethernet ports are isolated by transformers to prevent any nastiness caused by inter-building links.

You'll lose such isolation with some Power-over-Ethernet schemes though.

It is not unknown for data cable screens to be carrying earth currents between PCs where the "earth" potentials at the ends are different and the screen has been"earth" at both ends. Some worse case situations have had cables damaged by those earth currents.

Or in the event of a fault at the distant building, that data cable screen can end up carrying the bulk of the fault current if the building has an independent local earth.

 

[JohnW2]

It is probably only in a fire situation where insulation melts before the metal conductors melt that the safety of people using data equipment would be compromised by data cables in the same duct as power cables.
Fire in a small underground duct is un-likely. In larger ducts it is a possibility that has to be considered.
One small risk in a small duct is if chemicals get into the duct and damage insulation, some garden chemicals can rot PVC ( cannot remember which ).

All very true - but you're talking about risks that are already incredibly small, and eventualities which, even if they did occur, should not present a risk because of the presence of the 'earthed' SWA armour. For that to also somehow fail simultaneously (before some protective devices operate) is surely in the ballpark of 'vanishingly improbable'? My house might, after all, be hit by a meteorite!

Kind Regards, John.