Depends. LED lighting uses a transformer and rectifier to reduce the voltage to 12 VDC. In all of the better quality fixtures, I have detected no radio or emf interference from those fixtures and, therefore, there is no concern to data cable proximity.
However, some cheaply made junk (read that and translate ANY way you want) there is significant emf radiation, even 6 inches away from the fixture. These use a cylindrical transformer/rectifier unit rather than a well built and shielded "good quality" unit. I took one apart and found the transformer is a toroidal type and those are very well designed with proper filters to be clean, however the "junk" are notorious for being extremely "noisy" because they have zero filters or chokes.
A quick check for "dirty" fixtures is using an AM radio, place it within a foot of the fixture. If it is making a lot of noise, steer your data cable clear of the fixture. If it's quiet, wrap a few turns around the fixture for a "drip loop." (If you don't get the joke, don't install the "drip loop").
Rcaman
