Cable Types, Grounding and Routing
Use shielded twisted pair cable. We recommend cable with a foil shield and drain wire for ease of shield termination.
Copper conductors of size 24 AWG (0.22 mm2) are adequate for most installations. The conductors must be tinned copper wire to reduce corrosion problems.
The cable's temperature rating and resistance to corrosive environments must be appropriate for the conditions.
All sensors should have isolated housings with cable shields not connected at the sensor end (as per standard sensor wiring). This is to ensure that the online system, including all of its sensors, is only grounded at one location.
Never run signal cables parallel to AC power cables as 'mains hum' is likely to show up in the signals. Either run the signals in separate cable trays or maintain a separation of >= 0.5 m (1.5 ft). Keep clear of fluorescent light fittings for similar reasons.
If signal cables must cross power cables, make sure they do so at right angles (90°).
Cable signals must be protected from wear or abrasion points, which could damage the insulation material causing a short circuit.
Last Reviewed: 10/Jun/2009 Source: vbOnline Reference Guide Revision 11 April 2009 - page 14