cat5e faceplate and modem mounting next to power socket

How close can a cat5e faceplate and VDSL modem be mounted to a mains power socket?

Do you mean physically or how far apart to minimise noise?

To minimise noise go for at least 50mm or preferably 150mm but ensure that te cables do not follow the same path either and if they cross, they should do so at right angles.

Not sure about if there's a reg regarding distance between faceplates, but I popped my ADSL plate 50mm from the power plate. Anything less, and the plasterboard might be inclined to weaken.

I mean how close can they physically be mounted before noise is a problem?

There doesn't seem to be an official spec.

Noise management is often called a "black art" - I had RFI specialists working for me on various projects and whilst they would use standard methods for controlling and reducing interference there was also a lot of "suck it and see". It will depend on: level of noise relative to signal, material used for cable insulation, twisting of wires, back box, plasterboard (foil covered or not), frequency of noise, &c &c &c.

50mm between the sides is often enough, but if the noise source is close by the strength could be high and even 300mm not be enough.

Ok, thanks.