Martin Pentreath wrote:
[snip]
Phil, I'm a bit worried about your reported mains hum. All the cat5
cables from the ground floor go up to the attic via a convenient shaft
I found which takes the soil stack up through the building. Between
two floors there is a length of 2.5mm T&E mains cable sharing the
shaft. I can't think of another convenient way of routing the cat5 up
through the building, so I think I'll have to risk it. If anything it
would be easier to find another route for the mains cable. All these
cables are dangling loosely in the vertical shaft, so they shouldn't
be in very close proximity. I think it's just going to be fingers
crossed (no, I can't hear a bee on the line dear).

It might be worth you looking at FTP Cat5 cable which contains a foil
shielding to reduces interference. It's more expensive than the normal
UTP stuff, but you may find the extra shielding reduces the potential
interference from the mains cabling.

-Duncan