Practice has proved that, in an installation, it is also worthwhile physically separating the cables of different signals. A simple division into categories is helpful:
Category I: signal cables
⇒Field bus and LAN cables (e.g. PROFIBUS, Asi, Ethernet, etc…)
⇒Shielded cables for digital data (e.g. printer, RS232, etc...)
⇒Shielded cables for analogue and digital low voltage signals (<25V)
⇒Low voltage power supplies (<60V)
⇒Coaxial signal cables
Category II: low voltage
⇒Cables with DC voltages in range >60V and <400 V
⇒Cables with AC voltages in range >25V and <400 V
Category III: high voltage and high frequency
⇒Cables with DC and AC in voltage range >400 V
⇒Telephone cables !
Category IV: overhead lines
⇒Cables from categories I to II where there is a danger of surge voltages, e.g. due to lightning strikes
(e.g. connections between different buildings)
Cables from the same category can be laid together or directly alongside in one cable channel. Cables from different categories must maintain a minimum distance according to the following diagram and should ideally be carried in separate metallic channels or partitioning. If cables from different categories cross over each other, this should always occur at right angles. Under no circumstances should these cables be carried parallel to each other.
Distances between the cables of different categories